DeCS 
    2008 - March 17, 2008 version
    
       
        |  Alphabetic 
          Index of Descriptors   
           
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        |  | 
 | O Antigens | 
| O(6)-AGT use O(6)-Methylguanine-DNA Methyltransferase | 
| O(6)-Methylguanine Methyltransferase use O(6)-Methylguanine-DNA Methyltransferase | 
| O(6)-Methylguanine-DNA Methyltransferase | 
| O-Acetyl-ADP-Ribose | 
| O-Acetylserine Sulfhydrylase use Cysteine Synthase | 
| O-Demethylases use Oxidoreductases, O-Demethylating | 
| O-Specific Polysaccharides use O Antigens | 
| OAS use Organization of American States | 
| OB Receptor use Receptors, Leptin | 
| OECD use Organization for Economic Co-operation and Development | 
| OEI use Organization of Ibero-American States for Education, Science and Culture | 
| OHSAS 18000 | 
| OKM5 Antigen use Antigens, CD36 | 
| OMIM use Databases, Genetic | 
| OMP Proteins use Bacterial Outer Membrane Proteins | 
| ORFs use Open Reading Frames | 
| OSHA use United States Occupational Safety and Health Administration | 
| OTC Drugs use Drugs, Non-Prescription | 
| OX40 Ligand | 
| Oak Tree use Quercus | 
| Oak, Poison use Toxicodendron | 
| Oases | 
| Oats use Avena sativa | 
| Ob Protein use Leptin | 
| Obese Mice use Mice, Obese | 
| Obese Protein use Leptin | 
| Obesity | 
| Obesity Hypoventilation Syndrome | 
| Obesity, Morbid | 
| Obidoxime Chloride | 
| Object Attachment | 
| Object Relations use Object Attachment | 
| Objective Symptoms use Signs | 
| Obligation, Social use Social Responsibility | 
| Obligatory Vaccination | 
| Observation | 
| Observation Errors use Observer Variation | 
| Observational Studies | 
| Observer Bias use Observer Variation | 
| Observer Variation | 
| Obsessions use Obsessive Behavior | 
| Obsessive Behavior | 
| Obsessive-Compulsive Disorder | 
| Obsessive-Compulsive Personality use Compulsive Personality Disorder | 
| Obstetric Labor use Labor, Obstetric | 
| Obstetric Labor Complications | 
| Obstetric Labor, Premature | 
| Obstetric Surgical Procedures | 
| Obstetrical Analgesia use Analgesia, Obstetrical | 
| Obstetrical Forceps | 
| Obstetrical Nursing | 
| Obstetrics | 
| Obstetrics and Gynecology Department, Hospital | 
| Obstructions (Sewerage) | 
| Obstructive Hydrocephalus use Hydrocephalus | 
| Obstructive Sleep Apnea use Sleep Apnea, Obstructive | 
| Obstructive Subaortic Conus use Pulmonary Subvalvular Stenosis | 
| Obturator Hernia use Hernia, Obturator | 
| Obturator Nerve | 
| Obturators, Palatal use Palatal Obturators | 
| Occipital Bone | 
| Occipital Encephalocele use Encephalocele | 
| Occipital Lobe | 
| Occipital Region Trauma use Craniocerebral Trauma | 
| Occluded Front | 
| Occluding Junctions use Tight Junctions | 
| Occlusal Adjustment | 
| Occlusal Equilibration use Occlusal Adjustment | 
| Occlusal Force use Bite Force | 
| Occlusal Guidance use Dental Occlusion | 
| Occlusal Plane use Dental Occlusion | 
| Occlusal Splints | 
| Occlusal Wear, Restoration use Dental Restoration Wear | 
| Occlusive Dressings | 
| Occult Blood | 
| Occult Primary Neoplasms use Neoplasms, Unknown Primary | 
| Occultism | 
| Occupational Accidents Registry | 
| Occupational Air Pollutants use Air Pollutants, Occupational | 
| Occupational Cancer | 
| Occupational Dentistry | 
| Occupational Dermatitis use Dermatitis, Occupational | 
| Occupational Diseases | 
| Occupational Exposure | 
| Occupational Groups | 
| Occupational Health | 
| Occupational Health Nursing | 
| Occupational Health Physicians | 
| Occupational Health Policy | 
| Occupational Health Program | 
| Occupational Health Services | 
| Occupational Medicine | 
| Occupational Mortality | 
| Occupational Noise use Noise, Occupational | 
| Occupational Risks | 
| Occupational Safety use Occupational Health | 
| Occupational Safety and Health Administration (U.S.) use United States Occupational Safety and Health Administration | 
| Occupational Standards use OHSAS 18000 | 
| Occupational Therapy | 
| Occupational Therapy Department, Hospital | 
| Occupations | 
| Ocean Disposal of Hazardous Waste | 
| Ocean Dolphins use Dolphins | 
| Ocean Wave | 
| Oceania | 
| Oceanic Ancestry Group | 
| Oceanic Area | 
| Oceanic Flow | 
| Oceanic Plate | 
| Oceanic Pollution use Sea Water Pollution | 
| Oceanic Ridge | 
| Oceanic Slope | 
| Oceanic Storm use Marine Storm | 
| Oceanic Trench | 
| Oceanographic Chemistry | 
| Oceanographic Survey | 
| Oceanography | 
| Oceanology use Oceanography | 
| Oceanospirillaceae | 
| Oceans and Seas | 
| Ocelots use Felidae | 
| Ochanostachys use Olacaceae | 
| Ochlerotatus | 
| Ochna use Ochnaceae | 
| Ochnaceae | 
| Ochotona use Lagomorpha | 
| Ochradenus use Resedaceae | 
| Ochratoxins | 
| Ochre Suppressor Genes use Genes, Suppressor | 
| Ochrobactrum | 
| Ochrobactrum anthropi | 
| Ochroma use Bombacaceae | 
| Ochromonas | 
| Ochronosis | 
| Ochrosia | 
| Ocimum | 
| Ocimum basilicum | 
| Ocimum canum | 
| Ocimum sanctum | 
| Ockelbo Virus use Sindbis Virus | 
| Ocotea | 
| Oct-1 Transcription Factor use Octamer Transcription Factor-1 | 
| Oct-2 Transcription Factor use Octamer Transcription Factor-2 | 
| Oct-3 Transcription Factor use Octamer Transcription Factor-3 | 
| Oct-6 Transcription Factor use Octamer Transcription Factor-6 | 
| Octadecanoates use Stearates | 
| Octadecanoic Acids use Stearic Acids | 
| Octadecenoic Acids use Oleic Acids | 
| Octamer Transcription Factor-1 | 
| Octamer Transcription Factor-2 | 
| Octamer Transcription Factor-3 | 
| Octamer Transcription Factor-6 | 
| Octamer Transcription Factors | 
| Octanes | 
| Octanoates use Caprylates | 
| Octanoic Acids | 
| Octanols | 
| Octapressin use Felypressin | 
| Octodon | 
| Octogenarians use Aged, 80 and over | 
| Octopamine | 
| Octopoda use Octopodiformes | 
| Octopodiformes | 
| Octopus use Octopodiformes | 
| Octopus Venoms use Mollusk Venoms | 
| Octoxynol | 
| Octreotide | 
| Octreotide Acetate use Octreotide | 
| Octylphenoxypolyethoxyethanols use Octoxynol | 
| Ocular Disparity use Vision Disparity | 
| Ocular Fixation use Fixation, Ocular | 
| Ocular Fluorophotometry use Fluorophotometry | 
| Ocular Herpes zoster Virus use Herpesvirus 3, Human | 
| Ocular Hypertension | 
| Ocular Hypotension | 
| Ocular Hypotony use Ocular Hypotension | 
| Ocular Infections use Eye Infections | 
| Ocular Infections, Bacterial use Eye Infections, Bacterial | 
| Ocular Infections, Fungal use Eye Infections, Fungal | 
| Ocular Infections, Parasitic use Eye Infections, Parasitic | 
| Ocular Infections, Viral use Eye Infections, Viral | 
| Ocular Larva Migrans use Larva Migrans | 
| Ocular Motility Disorders | 
| Ocular Muscular Dystrophy use Ophthalmoplegia, Chronic Progressive External | 
| Ocular Physiologic Phenomena | 
| Ocular Physiologic Processes | 
| Ocular Physiological Phenomena use Ocular Physiologic Phenomena | 
| Ocular Physiological Processes use Ocular Physiologic Processes | 
| Ocular Physiology | 
| Ocular Prosthesis use Eye, Artificial | 
| Ocular Refraction use Refraction, Ocular | 
| Ocular Retraction Syndrome use Duane Retraction Syndrome | 
| Ocular Tension use Intraocular Pressure | 
| Ocular Torticollis use Ocular Motility Disorders | 
| Ocular Toxoplasmosis use Toxoplasmosis, Ocular | 
| Ocular Tuberculosis use Tuberculosis, Ocular | 
| Oculoauriculovertebral Syndrome use Goldenhar Syndrome | 
| Oculocerebrorenal Syndrome | 
| Oculomotor Muscles | 
| Oculomotor Nerve | 
| Oculomotor Nerve Diseases | 
| Oculomotor Paralysis use Ophthalmoplegia | 
| Oculomycosis use Eye Infections, Fungal | 
| Oculopharyngeal Spinal Muscular Atrophy use Muscular Atrophy, Spinal | 
| Oculosympathetic Syndrome use Horner Syndrome | 
| Ocytocin use Oxytocin | 
| Oddi's Sphincter use Sphincter of Oddi | 
| Odds Ratio | 
| Odobenidae use Walruses | 
| Odontalgia use Toothache | 
| Odontoblasts | 
| Odontoclasts use Osteoclasts | 
| Odontodysplasia | 
| Odontogenesis | 
| Odontogenesis Imperfecta use Odontodysplasia | 
| Odontogenic Cyst, Calcifying | 
| Odontogenic Cysts | 
| Odontogenic Dysplasia use Odontodysplasia | 
| Odontogenic Tumor, Squamous | 
| Odontogenic Tumors | 
| Odontoglossum Ringspot Virus use Tobamovirus | 
| Odontoid Process | 
| Odontoma | 
| Odontoma, Compound use Odontoma | 
| Odontome use Tooth Abnormalities | 
| Odontometry | 
| Odor Neutralizers use Odour Neutralizers | 
| Odorant Receptors use Receptors, Odorant | 
| Odors | 
| Odour Elimination use Deodorization | 
| Odour Neutralizers | 
| Oedipus Complex | 
| Oenanthe | 
| Oenanthe crocata | 
| Oenothera | 
| Oenothera biennis | 
| Oesophagostomiasis | 
| Oesophagostomum | 
| Oestradiol use Estradiol | 
| Oestronum use Folliculinum | 
| Oestrus cameli | 
| Off-Pump Coronary Artery Bypass use Coronary Artery Bypass, Off-Pump | 
| Off-Road Motor Vehicles | 
| Offensa Capitis use Stereotypic Movement Disorder | 
| Office Automation | 
| Office Buildings, Medical use Medical Office Buildings | 
| Office Environment use Working Environment | 
| Office Management | 
| Office Nursing | 
| Office Surgery use Ambulatory Surgical Procedures | 
| Office Visits | 
| Office for Human Research Protections use United States Office of Research Integrity | 
| Office of Economic Opportunity (U.S.) use United States Office of Economic Opportunity | 
| Office of Research Integrity (U.S.) use United States Office of Research Integrity | 
| Office of Scientific Integrity (U.S.) use United States Office of Research Integrity | 
| Office of Technology Assessment (U.S.) use United States Office of Technology Assessment | 
| Official Abstract | 
| Official Decisions | 
| Official Instructions | 
| Official Laboratory | 
| Official Letters | 
| Offshore Wind | 
| Offspring of Impaired Parents use Child of Impaired Parents | 
| Offspring, Adult use Adult Children | 
| Ofloxacin | 
| Ogilvie Syndrome use Colonic Pseudo-Obstruction | 
| Ohio | 
| Ohmic Resistance use Electric Impedance | 
| Oil Screens use Plumbing Accessories | 
| Oil Spills | 
| Oil and Fat Industry | 
| Oil of Cloves use Clove Oil | 
| Oil, Iodized use Iodized Oil | 
| Oils | 
| Oils, Essential use Oils, Volatile | 
| Oils, Plant use Plant Oils | 
| Oils, Unsaturated use Fats, Unsaturated | 
| Oils, Vegetable use Plant Oils | 
| Oils, Volatile | 
| Ointment Bases | 
| Ointments | 
| Oka Varicella Vaccine use Chickenpox Vaccine | 
| Okadaic Acid | 
| Okavirus use Roniviridae | 
| Oklahoma | 
| Okra use Abelmoschus | 
| Olacaceae | 
| Old Age Assistance | 
| Old Age Homes use Homes for the Aged | 
| Old Symptoms Return | 
| Old World Arenaviruses use Arenaviruses, Old World | 
| Old Yellow Enzyme use NADPH Dehydrogenase | 
| Oldenlandia | 
| Oldest Old use Aged, 80 and over | 
| Olea | 
| Oleaceae | 
| Oleander use Nerium | 
| Oleander (Homeopathy) | 
| Oleander Tree, Yellow use Thevetia | 
| Oleandomycin | 
| Oleanol use Oleanolic Acid | 
| Oleanolic Acid | 
| Oleate use Oleic Acid | 
| Oleavirus | 
| Olefins use Alkenes | 
| Oleic Acid | 
| Oleic Acids | 
| Oleum Animale use Oleum Animale Aethereum | 
| Oleum Animale Aethereum | 
| Oleum Cajuputi use Cajuputum | 
| Oleum Caryophyllatum | 
| Oleum Succinum | 
| Oleum jecoris aselli | 
| Oleum jecoris morrhuae use Oleum jecoris aselli | 
| Oleum myristicae | 
| Oleum santali | 
| Olfaction use Smell | 
| Olfaction Disorders | 
| Olfactory Bulb | 
| Olfactory Cortex use Olfactory Pathways | 
| Olfactory Epithelium use Olfactory Mucosa | 
| Olfactory Marker Protein | 
| Olfactory Mucosa | 
| Olfactory Nerve | 
| Olfactory Nerve Diseases | 
| Olfactory Neuroblastoma use Esthesioneuroblastoma, Olfactory | 
| Olfactory Pathways | 
| Olfactory Receptor Neurons | 
| Olfactory Receptor Proteins use Receptors, Odorant | 
| Olfactory Tract use Olfactory Pathways | 
| Olfactory Tubercle use Olfactory Pathways | 
| Olibanum use Boswellia | 
| Oligo-1,3-Glucosidase use Glucan Endo-1,3-beta-D-Glucosidase | 
| Oligo-1,6-Glucosidase | 
| Oligoastrocytoma, Mixed use Astrocytoma | 
| Oligochaeta | 
| Oligoclonal Bands | 
| Oligoclonal Immunoglobulins use Oligoclonal Bands | 
| Oligodendroblastoma use Oligodendroglioma | 
| Oligodendrocytes use Oligodendroglia | 
| Oligodendroglia | 
| Oligodendroglioma | 
| Oligodeoxyribonucleotide Primers use DNA Primers | 
| Oligodeoxyribonucleotide Probes use Oligonucleotide Probes | 
| Oligodeoxyribonucleotides | 
| Oligodeoxyribonucleotides, Antisense | 
| Oligogenic Inheritance use Multifactorial Inheritance | 
| Oligohydramnios | 
| Oligohymenophorea | 
| Oligomenorrhea | 
| Oligomycin D use Rutamycin | 
| Oligomycins | 
| Oligonucleotide Array Sequence Analysis | 
| Oligonucleotide Arrays use Oligonucleotide Array Sequence Analysis | 
| Oligonucleotide Primers use DNA Primers | 
| Oligonucleotide Probes | 
| Oligonucleotide-Directed Mutagenesis use Mutagenesis, Site-Directed | 
| Oligonucleotides | 
| Oligonucleotides, Antisense | 
| Oligopeptides | 
| Oligoribonucleotide Probes use Oligonucleotide Probes | 
| Oligoribonucleotides | 
| Oligoribonucleotides, Antisense | 
| Oligosaccharides | 
| Oligosaccharides, Branched-Chain | 
| Oligospermia | 
| Oligosymptomatic Patients | 
| Oligosymptomatics use Oligosymptomatic Patients | 
| Oliguria | 
| Olivary Nucleus | 
| Olive Baboon use Papio anubis | 
| Olive Latent Virus 1 use Tombusviridae | 
| Olive Oil use Vegetable Fats | 
| Olive Tree use Olea | 
| Olive latent virus 2 use Oleavirus | 
| Olive, Russian use Elaeagnaceae | 
| Olives use Olea | 
| Olivomycins | 
| Olivopontocerebellar Atrophies | 
| Olivopontocerebellar Atrophy, Idiopathic use Olivopontocerebellar Atrophies | 
| Ollier's Disease use Enchondromatosis | 
| Oman | 
| Omasum | 
| Omega-3 Fatty Acids use Fatty Acids, Omega-3 | 
| Omega-6 Fatty Acids use Fatty Acids, Omega-6 | 
| Omental Bursa use Peritoneal Cavity | 
| Omentum | 
| Omeprazole | 
| Omnopon use Opium | 
| Omphalocele use Hernia, Umbilical | 
| Omphalomesenteric Duct use Vitelline Duct | 
| Omsk hemorrhagic fever virus use Encephalitis Viruses, Tick-Borne | 
| On-Line Systems use Online Systems | 
| Onagraceae | 
| Onchocerca | 
| Onchocerca volvulus | 
| Onchocerciasis | 
| Onchocerciasis, Ocular | 
| Oncocytes use Oxyphil Cells | 
| Oncocytoma use Adenoma, Oxyphilic | 
| Oncogene Fusion | 
| Oncogene Products use Oncogene Proteins | 
| Oncogene Protein gp140(v-fms) | 
| Oncogene Protein p190(bcr-abl) use Fusion Proteins, bcr-abl | 
| Oncogene Protein p21(ras) | 
| Oncogene Protein p210(bcr-abl) use Fusion Proteins, bcr-abl | 
| Oncogene Protein p28(v-sis) use Oncogene Proteins v-sis | 
| Oncogene Protein p37(v-mos) use Oncogene Proteins v-mos | 
| Oncogene Protein p55(v-fos) use Oncogene Proteins v-fos | 
| Oncogene Protein p55(v-myc) | 
| Oncogene Protein p65(gag-jun) | 
| Oncogene Protein p75(gag-fos-fox) use Oncogene Proteins v-fos | 
| Oncogene Protein p85(gag-mos) use Oncogene Proteins v-mos | 
| Oncogene Protein pp59(v-rel) use Oncogene Proteins v-rel | 
| Oncogene Protein pp60(src) use Oncogene Protein pp60(v-src) | 
| Oncogene Protein pp60(v-src) | 
| Oncogene Protein tpr-met | 
| Oncogene Protein v-akt | 
| Oncogene Protein v-cbl | 
| Oncogene Protein v-crk | 
| Oncogene Protein v-jun use Oncogene Protein p65(gag-jun) | 
| Oncogene Protein v-maf | 
| Oncogene Proteins | 
| Oncogene Proteins v-abl | 
| Oncogene Proteins v-erbA | 
| Oncogene Proteins v-erbB | 
| Oncogene Proteins v-fos | 
| Oncogene Proteins v-mil use Oncogene Proteins v-raf | 
| Oncogene Proteins v-mos | 
| Oncogene Proteins v-myb | 
| Oncogene Proteins v-raf | 
| Oncogene Proteins v-rel | 
| Oncogene Proteins v-sis | 
| Oncogene Proteins, Fusion | 
| Oncogene Proteins, Viral | 
| Oncogenes | 
| Oncogenic Viruses | 
| Oncogens use Carcinogens | 
| Oncologic Nursing | 
| Oncology Service, Hospital | 
| Oncology, Medical use Medical Oncology | 
| Oncology, Radiation use Radiation Oncology | 
| Oncolytic Virotherapy | 
| Oncolytic Viruses | 
| Oncoproteins use Oncogene Proteins | 
| Oncorhynchus | 
| Oncorhynchus gorbuscha use Salmon | 
| Oncorhynchus keta | 
| Oncorhynchus kisutch | 
| Oncorhynchus mykiss | 
| Oncorhynchus nerka use Salmon | 
| Oncorhynchus tshawytscha use Salmon | 
| Oncornaviruses use Retroviridae | 
| Oncostatin M | 
| Oncostatin M Receptor beta Subunit | 
| Oncostatin M Type II Receptor use Receptors, Oncostatin M, Type II | 
| Oncovirinae use Retroviridae | 
| Oncoviruses use Retroviridae | 
| Oncoviruses, Type C use Retroviridae | 
| Ondansetron | 
| Ondatra use Arvicolinae | 
| Ondine Syndrome use Sleep Apnea, Central | 
| One-Carbon Group Transferases | 
| One-Hybrid System Techniques use Two-Hybrid System Techniques | 
| One-Parent Family use Single-Parent Family | 
| Onecut Transcription Factors | 
| Onions | 
| Oniscus asellus | 
| Onium Compounds | 
| Onlays use Inlays | 
| Online Mendelian Inheritance In Man use Databases, Genetic | 
| Online Service | 
| Online Systems | 
| Only Child | 
| Onoclea use Dryopteridaceae | 
| Ononis spinosa | 
| Onopordum | 
| Onosma use Boraginaceae | 
| Onosmodium virginianum | 
| Onshore Wind | 
| Ontario | 
| Onycholysis | 
| Onychomycosis | 
| Onychophagia use Nail Biting | 
| Onygenales | 
| Oocysts | 
| Oocyte Donation | 
| Oocyte Retrieval | 
| Oocytes | 
| Ooecyan use Biliverdine | 
| Oogenesis | 
| Oogonia | 
| Oomycetes | 
| Oomycota use Oomycetes | 
| Oophorectomy use Ovariectomy | 
| Oophorinum use Ovininum | 
| Oophoritis | 
| Open Access | 
| Open Access to Information use Access to Information | 
| Open Archives | 
| Open Bite | 
| Open Channels Flow use Closed Currents | 
| Open Dumps | 
| Open Filters use Gravity Filters | 
| Open Filtration use Gravity Filtration | 
| Open Population | 
| Open Reading Frames | 
| Open Trucks | 
| Open Water Networks | 
| Open Wells use Inspection Manholes | 
| Open-Angle Glaucoma use Glaucoma, Open-Angle | 
| Operating Room Information Systems | 
| Operating Room Nursing | 
| Operating Room Technicians | 
| Operating Rooms | 
| Operation Desert Storm use Gulf War | 
| Operation and Maintenance | 
| Operational Audit use Management Audit | 
| Operations Research | 
| Operator (Genetics) use Operator Regions (Genetics) | 
| Operator Regions (Genetics) | 
| Operators | 
| Operculina turpenthum | 
| Operon | 
| Operon, rRNA use rRNA Operon | 
| Ophiopogon | 
| Ophioxylon serpentinum use Rauwolfia serpentina | 
| Ophthalmia use Endophthalmitis | 
| Ophthalmia Neonatorum | 
| Ophthalmia, Sympathetic | 
| Ophthalmic Artery | 
| Ophthalmic Assistants | 
| Ophthalmic Nerve | 
| Ophthalmic Solutions | 
| Ophthalmodynamometry | 
| Ophthalmologic Services use Eye Health Services | 
| Ophthalmologic Surgical Procedures | 
| Ophthalmological Services use Eye Health Services | 
| Ophthalmology | 
| Ophthalmopathy, Infiltrative use Graves Ophthalmopathy | 
| Ophthalmopathy, Thyroid-Associated use Graves Ophthalmopathy | 
| Ophthalmoplegia | 
| Ophthalmoplegia, Ataxia and Areflexia Syndrome use Miller Fisher Syndrome | 
| Ophthalmoplegia, Chronic Progressive External | 
| Ophthalmoplegia, Progressive Supranuclear use Supranuclear Palsy, Progressive | 
| Ophthalmoscopes | 
| Ophthalmoscopy | 
| Opiate Addiction use Opioid-Related Disorders | 
| Opiate Alkaloids | 
| Opiate Dependence use Opioid-Related Disorders | 
| Opiates, Endogenous use Opioid Peptides | 
| Opioid Analgesics use Analgesics, Opioid | 
| Opioid Antagonists use Narcotic Antagonists | 
| Opioid Peptides | 
| Opioid Receptors use Receptors, Opioid | 
| Opioid Receptors, delta use Receptors, Opioid, delta | 
| Opioid Receptors, kappa use Receptors, Opioid, kappa | 
| Opioid Receptors, mu use Receptors, Opioid, mu | 
| Opioid Receptors, sigma use Receptors, sigma | 
| Opioid-Related Disorders | 
| Opioids use Analgesics, Opioid | 
| Opipramol | 
| Opisthorchiasis | 
| Opisthorchidae | 
| Opisthorchis | 
| Opisthorchis felineus use Opisthorchis | 
| Opisthorchis sinensis use Clonorchis sinensis | 
| Opisthorchis viverrini use Opisthorchis | 
| Opium | 
| Opium (Homeopathy) | 
| Oplia farinosa | 
| Oplopanax | 
| Opopanax chironium | 
| Opossum, North American use Didelphis | 
| Opossums | 
| Opossums, Short-Tailed use Monodelphis | 
| Opotherapy | 
| Oppenheim Disease use Neuromuscular Diseases | 
| Oppenheim-Ziehen Disease use Dystonia Musculorum Deformans | 
| Opportunistic Infections | 
| Opportunistic Infections, AIDS-Related use AIDS-Related Opportunistic Infections | 
| Opportunistic Infections, HIV-Related use AIDS-Related Opportunistic Infections | 
| Oppositional Defiant Disorder use Attention Deficit and Disruptive Behavior Disorders | 
| Opsanus use Batrachoidiformes | 
| Opsin | 
| Opsoclonus use Ocular Motility Disorders | 
| Opsoclonus-Myoclonus Syndrome | 
| Opsonin Proteins | 
| Opsonins use Opsonin Proteins | 
| Optic Atrophies, Hereditary | 
| Optic Atrophy | 
| Optic Atrophy, Autosomal Dominant | 
| Optic Atrophy, Hereditary, Autosomal Dominant use Optic Atrophy, Autosomal Dominant | 
| Optic Atrophy, Hereditary, Leber | 
| Optic Chiasm | 
| Optic Disk | 
| Optic Disk Disorders use Optic Nerve Diseases | 
| Optic Disk Drusen | 
| Optic Disk Edema use Papilledema | 
| Optic Lobe, Human use Superior Colliculi | 
| Optic Lobe, Mammalian use Superior Colliculi | 
| Optic Lobe, Nonmammalian | 
| Optic Nerve | 
| Optic Nerve Diseases | 
| Optic Nerve Glioma | 
| Optic Nerve Head use Optic Disk | 
| Optic Nerve Injuries | 
| Optic Nerve Ischemia use Optic Neuropathy, Ischemic | 
| Optic Nerve Neoplasms | 
| Optic Nerve Sheath Tumors use Optic Nerve Neoplasms | 
| Optic Nerve Trauma use Optic Nerve Injuries | 
| Optic Neuritis | 
| Optic Neuropathy use Optic Nerve Diseases | 
| Optic Neuropathy, Ischemic | 
| Optic Neuropathy, Traumatic use Optic Nerve Injuries | 
| Optic Papilla use Optic Disk | 
| Optic Papilla Edema use Papilledema | 
| Optic Tectum use Superior Colliculi | 
| Optic Tract use Visual Pathways | 
| Optical Illusions | 
| Optical Readers use Automatic Data Processing | 
| Optical Rotation | 
| Optical Rotatory Dispersion | 
| Optical Storage Devices | 
| Optical Tweezers | 
| Optics | 
| Optimization | 
| Optometry | 
| Opuntia | 
| Opuntia ficus | 
| Opuntia ficus-indica use Opuntia ficus | 
| Opuntia vulgaris | 
| Oral Cancer use Mouth Neoplasms | 
| Oral Cavity use Mouth | 
| Oral Character use Psychoanalytic Theory | 
| Oral Erotic Stage use Oral Stage | 
| Oral Examination use Diagnosis, Oral | 
| Oral Fistula | 
| Oral Hairy Leukoplakia use Leukoplakia, Hairy | 
| Oral Health | 
| Oral Hemorrhage | 
| Oral Hygiene | 
| Oral Hygiene Index | 
| Oral Manifestations | 
| Oral Medicine | 
| Oral Mucosa use Mouth Mucosa | 
| Oral Mucositis use Stomatitis | 
| Oral Myotherapy use Myofunctional Therapy | 
| Oral Neoplasms use Mouth Neoplasms | 
| Oral Pulvinar Nucleus use Pulvinar | 
| Oral Rehydration Therapy use Fluid Therapy | 
| Oral Sadistic Stage use Oral Stage | 
| Oral Sex use Sexual Behavior | 
| Oral Stage | 
| Oral Submucous Fibrosis | 
| Oral Surgical Procedures | 
| Oral Surgical Procedures, Preprosthetic | 
| Oral Tobacco use Tobacco, Smokeless | 
| Oral Ulcer | 
| Oral and Dental Hygiene Products | 
| Orange Tree use Citrus sinensis | 
| Orange Tree, Bitter use Citrus | 
| Orange Tree, Mandarin use Citrus | 
| Orange Tree, Seville use Citrus | 
| Orange Tree, Sour use Citrus | 
| Orange, Osage use Maclura | 
| Orange, Trifoliate use Poncirus | 
| Oranges use Citrus sinensis | 
| Orangutan use Pongo pygmaeus | 
| Orbicularis Oculi Reflex use Blinking | 
| Orbit | 
| Orbit Evisceration | 
| Orbital Cellulitis | 
| Orbital Diseases | 
| Orbital Fractures | 
| Orbital Granuloma, Plasma Cell use Granuloma, Plasma Cell, Orbital | 
| Orbital Implants | 
| Orbital Myositis use Granuloma, Plasma Cell, Orbital | 
| Orbital Neoplasms | 
| Orbital Simulation use Space Simulation | 
| Orbivirus | 
| Orchardgrass use Dactylis | 
| Orchidaceae | 
| Orchidectomy use Orchiectomy | 
| Orchiectomy | 
| Orchitinum | 
| Orchitis | 
| Orciprenaline | 
| Order Entry Systems, Medical use Medical Order Entry Systems | 
| Orderly Departure | 
| Ordinances | 
| Oregano use Origanum | 
| Oregano Plant use Origanum | 
| Oregon | 
| Oreochromis mossambicus use Tilapia | 
| Oreochromis niloticus use Cichlids | 
| Oreodaphne californica | 
| Orf use Ecthyma, Contagious | 
| Orf virus | 
| Organ Culture Techniques | 
| Organ Donors use Tissue Donors | 
| Organ Dysfunction Syndrome, Multiple use Multiple Organ Failure | 
| Organ Failure, Multiple use Multiple Organ Failure | 
| Organ Grafts use Transplants | 
| Organ Harvesting use Tissue and Organ Harvesting | 
| Organ Preservation | 
| Organ Preservation Solutions | 
| Organ Procurement use Tissue and Organ Procurement | 
| Organ Procurement Systems use Tissue and Organ Procurement | 
| Organ Retrieval use Tissue and Organ Harvesting | 
| Organ Size | 
| Organ Specificity | 
| Organ Survival use Tissue Survival | 
| Organ Temperature use Body Temperature | 
| Organ Transplantation | 
| Organ Transplants use Transplants | 
| Organ Volume use Organ Size | 
| Organ Weight use Organ Size | 
| Organ of Corti | 
| Organelle Shape | 
| Organelle Size | 
| Organelles | 
| Organic Acids | 
| Organic Agriculture | 
| Organic Anion Transport Polypeptide C | 
| Organic Anion Transport Polypeptides use Organic Anion Transporters | 
| Organic Anion Transport Protein 1 | 
| Organic Anion Transporters | 
| Organic Anion Transporters, ATP-Dependent | 
| Organic Anion Transporters, Sodium-Dependent | 
| Organic Anion Transporters, Sodium-Independent | 
| Organic Beds | 
| Organic Brain Syndrome, Nonpsychotic use Delirium, Dementia, Amnestic, Cognitive Disorders | 
| Organic Cation Transport Proteins | 
| Organic Cation Transporter 1 | 
| Organic Chemicals | 
| Organic Food use Health Food | 
| Organic Law | 
| Organic Load | 
| Organic Matter | 
| Organic Mental Disorders use Delirium, Dementia, Amnestic, Cognitive Disorders | 
| Organic Mental Disorders, Psychotic use Delirium, Dementia, Amnestic, Cognitive Disorders | 
| Organic Mental Disorders, Substance-Induced use Substance-Related Disorders | 
| Organic Particles | 
| Organic Pollutants | 
| Organic Production use Organic Agriculture | 
| Organic Substances use Organic Chemicals | 
| Organic Wastes | 
| OrganicTracers | 
| Organicism | 
| Organisms, Genetically Modified | 
| Organisms, Transgenic use Organisms, Genetically Modified | 
| Organization and Administration | 
| Organization and Administration, Hospital use Hospital Administration | 
| Organization for Economic Co-operation and Development | 
| Organization of American States | 
| Organization of Ibero-American States for Education, Science and Culture | 
| Organizational Affiliation | 
| Organizational Capacity use Health Management | 
| Organizational Case Studies | 
| Organizational Change use Organizational Innovation | 
| Organizational Culture | 
| Organizational Decision Making use Decision Making, Organizational | 
| Organizational Efficiency use Efficiency, Organizational | 
| Organizational Ethics use Ethics, Institutional | 
| Organizational Innovation | 
| Organizational Models use Models, Organizational | 
| Organizational Modernization | 
| Organizational Objectives | 
| Organizational Policy | 
| Organizations | 
| Organizations for Planning and Care in Disasters | 
| Organizations, Committees and Conventions | 
| Organizations, Nonprofit | 
| Organizers, Embryonic | 
| Organochlorine Insecticides use Insecticides, Organochlorine | 
| Organochlorine Pesticides use Insecticides, Organochlorine | 
| Organogenesis | 
| Organogold Compounds | 
| Organoid Nevus Phakomatosis use Nevus Sebaceous of Jadassohn | 
| Organoids | 
| Organomercury Compounds | 
| Organometallic Compounds | 
| Organon | 
| Organon: Sections 1 To 10 | 
| Organon: Sections 101 To 110 | 
| Organon: Sections 11 To 20 | 
| Organon: Sections 111 To 120 | 
| Organon: Sections 121 To 130 | 
| Organon: Sections 131 To 140 | 
| Organon: Sections 141 To 150 | 
| Organon: Sections 151 To 160 | 
| Organon: Sections 161 To 170 | 
| Organon: Sections 171 To 180 | 
| Organon: Sections 181 To 190 | 
| Organon: Sections 191 To 200 | 
| Organon: Sections 201 To 210 | 
| Organon: Sections 21 To 30 | 
| Organon: Sections 211 To 220 | 
| Organon: Sections 221 To 230 | 
| Organon: Sections 231 To 240 | 
| Organon: Sections 241 To 250 | 
| Organon: Sections 251 To 260 | 
| Organon: Sections 261 To 270 | 
| Organon: Sections 271 To 280 | 
| Organon: Sections 281 To 291 | 
| Organon: Sections 31 To 40 | 
| Organon: Sections 41 To 50 | 
| Organon: Sections 51 To 60 | 
| Organon: Sections 61 To 70 | 
| Organon: Sections 71 To 80 | 
| Organon: Sections 81 T0 90 | 
| Organon: Sections 91 To 100 | 
| Organophosphate Insecticide Antagonists use Cholinesterase Reactivators | 
| Organophosphate Insecticides use Insecticides, Organophosphate | 
| Organophosphate Pesticides use Insecticides, Organophosphate | 
| Organophosphorous Insecticides use Insecticides, Organophosphate | 
| Organophosphorous Pesticides use Insecticides, Organophosphate | 
| Organophosphorus Compounds | 
| Organophosphorus Pesticides use Insecticides, Organophosphate | 
| Organoplatinum Compounds | 
| Organoselenium Compounds | 
| Organosilicon Compounds | 
| Organotechnetium Compounds | 
| Organotherapy | 
| Organothiophosphate Insecticide Antagonists use Cholinesterase Reactivators | 
| Organothiophosphate Insecticides use Insecticides, Organophosphate | 
| Organothiophosphorus Compounds | 
| Organotin Compounds | 
| Organotropism use Medicamentous Tropism | 
| Organs of Zuckerkandl use Para-Aortic Bodies | 
| Organum Vasculosum Laminae Terminalis use Hypothalamus | 
| Organum Vomeronasale use Vomeronasal Organ | 
| Orgasm | 
| Orgasmic Disorder use Sexual Dysfunctions, Psychological | 
| Oriental Medicine, Traditional use Medicine, Oriental Traditional | 
| Oriental Republic of Uruguay use Uruguay | 
| Oriental Sore use Leishmaniasis, Cutaneous | 
| Orientation | 
| Orientation Programs, Employee use Inservice Training | 
| Orientia tsutsugamushi | 
| Orifice Valves | 
| Origanum | 
| Origanum creticum | 
| Origanum majorana | 
| Origanum vulgare | 
| Origin Recognition Complex | 
| Origin of Life use Biogenesis | 
| Origin of Replication use Replication Origin | 
| Ormond Disease use Retroperitoneal Fibrosis | 
| Ornidazole | 
| Ornipressin | 
| Ornithine | 
| Ornithine Aminotransferase use Ornithine-Oxo-Acid Transaminase | 
| Ornithine Carbamoyltransferase | 
| Ornithine Carbamoyltransferase Deficiency Disease | 
| Ornithine Carboxy-lyase use Ornithine Decarboxylase | 
| Ornithine Decarboxylase | 
| Ornithine Transaminase use Ornithine-Oxo-Acid Transaminase | 
| Ornithine Transcarbamylase use Ornithine Carbamoyltransferase | 
| Ornithine Transcarbamylase Deficiency Disease use Ornithine Carbamoyltransferase Deficiency Disease | 
| Ornithine Vasopressin use Ornipressin | 
| Ornithine-Oxo-Acid Transaminase | 
| Ornithobacterium | 
| Ornithodoros | 
| Ornithogalum | 
| Ornithogalum umbellatum | 
| Ornithosis use Psittacosis | 
| Oroantral Fistula | 
| Orobanchaceae | 
| Orobanche | 
| Orofacial Dyskinesia use Movement Disorders | 
| Orofacial Pain use Facial Pain | 
| Orofaciodigital Syndromes | 
| Orontium use Araceae | 
| Oropharyngeal Cancer use Oropharyngeal Neoplasms | 
| Oropharyngeal Neoplasms | 
| Oropharynx | 
| Orosomucoid | 
| Orotate Phosphoribosyltransferase | 
| Orotic Acid | 
| Orotidine Phosphate Carboxy-Lyase use Orotidine-5'-Phosphate Decarboxylase | 
| Orotidine-5'-Phosphate Decarboxylase | 
| Orotidine-5'-Phosphate Pyrophosphorylase use Orotate Phosphoribosyltransferase | 
| Orotidylate Decarboxylase use Orotidine-5'-Phosphate Decarboxylase | 
| Orotidylic Acid Phosphorylase use Orotate Phosphoribosyltransferase | 
| Oroya Fever use Bartonella Infections | 
| Orphan Drug Production | 
| Orphan Drugs use Exceptional Drugs | 
| Orphanages | 
| Orphans use Child, Orphaned | 
| Orphenadrine | 
| Orpinomyces use Neocallimasticales | 
| Orpressin use Ornipressin | 
| Orteaga use Eysenhardtia polystachia | 
| Orthobunyavirus | 
| Orthodontic Anchorage Procedures | 
| Orthodontic Appliance Design | 
| Orthodontic Appliances | 
| Orthodontic Appliances, Activator use Activator Appliances | 
| Orthodontic Appliances, Functional | 
| Orthodontic Appliances, Removable | 
| Orthodontic Brackets | 
| Orthodontic Extrusion | 
| Orthodontic Retainers | 
| Orthodontic Space Closure | 
| Orthodontic Wires | 
| Orthodontics | 
| Orthodontics, Corrective | 
| Orthodontics, Interceptive | 
| Orthodontics, Preventive | 
| Orthohepadnavirus | 
| Orthokeratologic Procedures | 
| Orthokinetic Flocculation | 
| Orthomolecular Therapy | 
| Orthomyxoviridae | 
| Orthomyxoviridae Infections | 
| Orthomyxovirus Infections use Orthomyxoviridae Infections | 
| Orthomyxovirus Type A use Influenza A virus | 
| Orthomyxovirus Type A, Avian use Influenza A virus | 
| Orthomyxovirus Type A, Human use Influenza A virus | 
| Orthomyxovirus Type A, Porcine use Influenza A virus | 
| Orthomyxoviruses Type B use Influenza B virus | 
| Orthomyxoviruses Type C use Influenzavirus C | 
| Orthomyxoviruses Type D use Thogotovirus | 
| Orthopantomography use Radiography, Panoramic | 
| Orthopedic Equipment | 
| Orthopedic Fixation Devices | 
| Orthopedic Manipulation use Manipulation, Orthopedic | 
| Orthopedic Nursing | 
| Orthopedic Procedures | 
| Orthopedic Surgery use Orthopedics | 
| Orthopedics | 
| Orthopoxvirus | 
| Orthopsychiatry | 
| Orthoptera | 
| Orthoptics | 
| Orthoreovirus | 
| Orthoreovirus, Avian | 
| Orthoreovirus, Baboon use Orthoreovirus | 
| Orthoreovirus, Mammalian | 
| Orthoreovirus, Nelson Bay use Orthoreovirus | 
| Orthoses use Orthotic Devices | 
| Orthosiphon | 
| Orthosis use Orthotic Devices | 
| Orthostasis use Dizziness | 
| Orthostatic Hypotension, Dysautonomic use Shy-Drager Syndrome | 
| Orthotic Devices | 
| Orthovanadate use Vanadates | 
| Ortonal use Methaqualone | 
| Oryctes Viruses use Baculoviridae | 
| Oryza use Oryza sativa | 
| Oryza sativa | 
| Oryzavirus use Reoviridae | 
| Oryzias | 
| Oryzomys use Sigmodontinae | 
| Os Trigonum use Talus | 
| Osage Orange use Maclura | 
| Oscillatoria | 
| Oscillators, Endogenous use Biological Clocks | 
| Oscillococcinum | 
| Oscillometry | 
| Oscines use Songbirds | 
| Oseltamivir | 
| Osgood-Schlatter Disease use Osteochondritis | 
| Osler-Rendu Disease use Telangiectasia, Hereditary Hemorrhagic | 
| Osler-Vaquez Disease use Polycythemia Vera | 
| Osmeridae use Osmeriformes | 
| Osmeriformes | 
| Osmic Acid use Osmium Tetroxide | 
| Osmium | 
| Osmium Compounds | 
| Osmium Metallicum | 
| Osmium Tetroxide | 
| Osmolality use Osmolar Concentration | 
| Osmolar Concentration | 
| Osmolarity use Osmolar Concentration | 
| Osmoregulation use Water-Electrolyte Balance | 
| Osmosis | 
| Osmotic Diuretics use Diuretics, Osmotic | 
| Osmotic Fragility | 
| Osmotic Pressure | 
| Osmotic Shock use Osmotic Pressure | 
| Osseointegrated Dental Implantation use Dental Implantation, Endosseous | 
| Osseointegration | 
| Ossicular Prosthesis | 
| Ossicular Prosthesis Implantation use Ossicular Replacement | 
| Ossicular Replacement | 
| Ossicular Replacement Prosthesis use Ossicular Prosthesis | 
| Ossification of Posterior Longitudinal Ligament | 
| Ossification, Heterotopic | 
| Ossification, Pathologic use Ossification, Heterotopic | 
| Ossification, Physiologic use Osteogenesis | 
| Osteitis | 
| Osteitis Deformans | 
| Osteitis Fibrosa Cystica | 
| Osteitis Fibrosa Disseminata use Fibrous Dysplasia of Bone | 
| Osteitis, Alveolar use Dry Socket | 
| Osteo-Onychodysplasia, Hereditary use Nail-Patella Syndrome | 
| Osteoarthritis | 
| Osteoarthritis, Hip | 
| Osteoarthritis, Knee | 
| Osteoarthropathy, Primary Hypertrophic | 
| Osteoarthropathy, Secondary Hypertrophic | 
| Osteoarthrosis use Osteoarthritis | 
| Osteoarthrosis Deformans use Osteoarthritis | 
| Osteoblastoma | 
| Osteoblasts | 
| Osteocalcin | 
| Osteochondritis | 
| Osteochondritis Dissecans | 
| Osteochondrodysplasias | 
| Osteochondroma | 
| Osteochondromas, Multiple use Exostoses, Multiple Hereditary | 
| Osteochondromatosis | 
| Osteochondromatosis, Synovial use Chondromatosis, Synovial | 
| Osteochondrosis use Osteochondritis | 
| Osteoclastic Bone Loss use Bone Resorption | 
| Osteoclastogenesis Inhibitory Factor use Osteoprotegerin | 
| Osteoclasts | 
| Osteocytes | 
| Osteogenesis | 
| Osteogenesis Imperfecta | 
| Osteogenesis, Distraction | 
| Osteolysis | 
| Osteolysis, Essential | 
| Osteolysis, Idiopathic Multicentric use Osteolysis, Essential | 
| Osteolysis, Massive use Osteolysis, Essential | 
| Osteolysis, Multicentric use Hajdu-Cheney Syndrome | 
| Osteoma | 
| Osteoma, Giant Osteoid use Osteoblastoma | 
| Osteoma, Osteoid | 
| Osteomalacia | 
| Osteomyelitis | 
| Osteon use Haversian System | 
| Osteonecrosis | 
| Osteonectin | 
| Osteopathic Manipulation use Manipulation, Osteopathic | 
| Osteopathic Medicine | 
| Osteopathy use Osteopathic Medicine | 
| Osteopenia use Bone Diseases, Metabolic | 
| Osteopetrosis | 
| Osteophyte | 
| Osteophytosis, Spinal use Spinal Osteophytosis | 
| Osteopoikilosis | 
| Osteopontin | 
| Osteoporosis | 
| Osteoporosis, Age-Related use Osteoporosis | 
| Osteoporosis, Post-Traumatic use Osteoporosis | 
| Osteoporosis, Postmenopausal | 
| Osteoporosis, Senile use Osteoporosis | 
| Osteoprotegerin | 
| Osteoradionecrosis | 
| Osteosarcoma | 
| Osteosarcoma, Juxtacortical | 
| Osteosclerosis | 
| Osteosclerosis Fragilis use Osteopetrosis | 
| Osteosynthesis, Fracture use Fracture Fixation, Internal | 
| Osteosynthesis, Fracture, Intramedullary use Fracture Fixation, Intramedullary | 
| Osteotomy | 
| Osteotomy, Le Fort | 
| Osterreicher Syndrome use Nail-Patella Syndrome | 
| Ostertagia | 
| Ostertagia ostertagi use Ostertagia | 
| Ostertagiasis | 
| Ostomy | 
| Ostracoda use Crustacea | 
| Ostrea | 
| Ostreidae | 
| Ostriches use Struthioniformes | 
| Ostriches, American use Rheiformes | 
| Ostrya use Betulaceae | 
| Ostrya virginica | 
| Ota's Nevus use Nevus of Ota | 
| Otalgia use Earache | 
| Oteracil use Oxonic Acid | 
| Otitis | 
| Otitis Externa | 
| Otitis Interna use Labyrinthitis | 
| Otitis Media | 
| Otitis Media with Effusion | 
| Otitis Media, Purulent use Otitis Media, Suppurative | 
| Otitis Media, Secretory use Otitis Media with Effusion | 
| Otitis Media, Serous use Otitis Media with Effusion | 
| Otitis Media, Suppurative | 
| Otoacoustic Emissions, Spontaneous | 
| Otoconia use Otolithic Membrane | 
| Otolaryngologic Diseases use Otorhinolaryngologic Diseases | 
| Otolaryngology | 
| Otolithic Membrane | 
| Otoliths use Otolithic Membrane | 
| Otologic Diseases use Ear Diseases | 
| Otologic Surgical Procedures | 
| Otology use Otolaryngology | 
| Otorhinolaryngologic Diseases | 
| Otorhinolaryngologic Neoplasms | 
| Otorhinolaryngologic Surgical Procedures | 
| Otorhinolaryngology use Otolaryngology | 
| Otosclerosis | 
| Otoscopes | 
| Otoscopy | 
| Otospongiosis use Otosclerosis | 
| Otsuka-Long-Evans-Tokushima Fatty Rats use Rats, Inbred OLETF | 
| Otsuka-Long-Evans-Tokushima Rats use Rats, Inbred OLETF | 
| Ottelia use Hydrocharitaceae | 
| Otters | 
| Otx Transcription Factors | 
| Ouabain | 
| Ouabainum | 
| Ouratea use Ochnaceae | 
| Ouro Preto Protocol | 
| Outbreaks use Disease Outbreaks | 
| Outcome Assessment (Health Care) | 
| Outcome Measurement Errors use Bias (Epidemiology) | 
| Outcome and Process Assessment (Health Care) | 
| Outcomes Research use Outcome Assessment (Health Care) | 
| Outdoor Air | 
| Outer Membrane Proteins, Bacterial use Bacterial Outer Membrane Proteins | 
| Outfalls | 
| Outliers, DRG | 
| Outlines | 
| Outpatient Care use Ambulatory Care | 
| Outpatient Clinics use Ambulatory Care Facilities | 
| Outpatient Clinics, Hospital | 
| Outpatient Health Services use Ambulatory Care | 
| Outpatient Health Services (Public Health) use Ambulatory Health Services | 
| Outpatient Infusion Therapy use Home Infusion Therapy | 
| Outpatient Monitoring use Monitoring, Ambulatory | 
| Outpatient Surgery use Ambulatory Surgical Procedures | 
| Outpatients | 
| Outsourced Services | 
| Outsourcing use Outsourced Services | 
| Oval Window, Ear | 
| Ovalbumin | 
| Ovalocytosis, Hereditary use Elliptocytosis, Hereditary | 
| Ovarian Cancer use Ovarian Neoplasms | 
| Ovarian Cycle use Menstrual Cycle | 
| Ovarian Cysts | 
| Ovarian Diseases | 
| Ovarian Failure, Premature | 
| Ovarian Follicle | 
| Ovarian Function Tests | 
| Ovarian Hyperstimulation Syndrome | 
| Ovarian Interstitial Cells use Theca Cells | 
| Ovarian Neoplasms | 
| Ovarian Pregnancy use Pregnancy, Ectopic | 
| Ovarian Stimulation use Ovulation Induction | 
| Ovariectomy | 
| Ovary | 
| Over-the-Counter Drugs use Drugs, Non-Prescription | 
| Overactive Detrusor use Urinary Bladder, Overactive | 
| Overall | 
| Overall and Gorham Brief Psychiatric Rating Scale use Brief Psychiatric Rating Scale | 
| Overdenture use Denture, Overlay | 
| Overdose | 
| Overeating use Hyperphagia | 
| Overflows use Floods (Disasters) | 
| Overinclusion use Cognition Disorders | 
| Overlearning | 
| Overnight Hospital Stay use Hospitalization | 
| Overnutrition | 
| Overpopulation use Population Density | 
| Overspill | 
| Overthrust Fault use Geologic Fault, Reverse | 
| Overuse Syndrome use Cumulative Trauma Disorders | 
| Overutilization of Health Services use Health Services Misuse | 
| Overweight | 
| Ovi Testa use Calcarea Ovi Testae | 
| Ovi gallinae pellicula | 
| Oviducts | 
| Oviducts, Mammalian use Fallopian Tubes | 
| Ovine Catarrhal Fever Virus use Bluetongue virus | 
| Ovine adenovirus D use Atadenovirus | 
| Ovine pulmonary adenocarcinoma virus use Jaagsiekte sheep retrovirus | 
| Ovine-Caprine Lentiviruses use Lentiviruses, Ovine-Caprine | 
| Ovininum | 
| Oviparity | 
| Oviposition | 
| Ovis use Sheep | 
| Ovocytes use Oocytes | 
| Ovomucin | 
| Ovomucoid use Ovomucin | 
| Ovotransferrin use Conalbumin | 
| Ovoviviparity | 
| Ovulation | 
| Ovulation Detection | 
| Ovulation Induction | 
| Ovulation Inhibition | 
| Ovulation Prediction | 
| Ovum | 
| Ovum Donation use Oocyte Donation | 
| Ovum Implantation use Embryo Implantation | 
| Ovum Implantation, Delayed use Embryo Implantation, Delayed | 
| Ovum Proteins use Egg Proteins | 
| Ovum Transport | 
| Ovum, Fertilized use Zygote | 
| Ovum-Sperm Interactions use Sperm-Ovum Interactions | 
| Owl Monkey use Aotidae | 
| Owls use Strigiformes | 
| Ownership | 
| Owren Disease use Factor V Deficiency | 
| Oxacillin | 
| Oxadiazoles | 
| Oxalamic Acid use Oxamic Acid | 
| Oxalates | 
| Oxalic Acid | 
| Oxalic Acids | 
| Oxalicum Acidum | 
| Oxalis acetosella | 
| Oxaloacetate | 
| Oxaloacetates | 
| Oxaloacetic Acids | 
| Oxalobacter use Oxalobacter formigenes | 
| Oxalobacter formigenes | 
| Oxalobacteraceae | 
| Oxalosuccinic Acid use Oxalosuccinicum Acidum | 
| Oxalosuccinicum Acidum | 
| Oxaluria use Hyperoxaluria | 
| Oxaluria, Primary use Hyperoxaluria, Primary | 
| Oxamic Acid | 
| Oxamidic Acid use Oxamic Acid | 
| Oxamniquine | 
| Oxandrolone | 
| Oxathiins | 
| Oxazepam | 
| Oxazepines | 
| Oxazimedrine use Phenmetrazine | 
| Oxazines | 
| Oxazocilline use Oxacillin | 
| Oxazocines | 
| Oxazoles | 
| Oxazolidin-2-one use Oxazolidinones | 
| Oxazolidinones | 
| Oxazolone | 
| Oxepins | 
| Oxeye Daisy use Adonis | 
| Oxiconum use Oxycodone | 
| Oxidant Gases | 
| Oxidants | 
| Oxidants, Photochemical | 
| Oxidases use Oxidoreductases | 
| Oxidation | 
| Oxidation Ditches | 
| Oxidation Ponds Activated Sludges use Prolonged Aeration Activated Sludges | 
| Oxidation-Reduction | 
| Oxidative Burst use Respiratory Burst | 
| Oxidative Phosphorylation | 
| Oxidative Phosphorylation Coupling Factors | 
| Oxidative Phosphorylation Deficiencies use Mitochondrial Diseases | 
| Oxidative Stress | 
| Oxides | 
| Oxidizing Agents use Oxidants | 
| Oxidizing Substances, Products and Materials | 
| Oxidopamine | 
| Oxidoreductases | 
| Oxidoreductases Acting on Aldehyde or Oxo Group Donors | 
| Oxidoreductases Acting on CH-CH Group Donors | 
| Oxidoreductases Acting on CH-NH Group Donors | 
| Oxidoreductases Acting on CH-NH2 Group Donors | 
| Oxidoreductases Acting on Sulfur Group Donors | 
| Oxidoreductases, N-Demethylating | 
| Oxidoreductases, NADH, NADPH use NADH, NADPH Oxidoreductases | 
| Oxidoreductases, O-Demethylating | 
| Oxilapine use Loxapine | 
| Oximes | 
| Oximetry | 
| Oximetry, Transcutaneous use Blood Gas Monitoring, Transcutaneous | 
| Oxine use Oxyquinoline | 
| Oxipurinol use Oxypurinol | 
| Oxo-Acid-Lyases | 
| Oxocholesterols use Ketocholesterols | 
| Oxocins | 
| Oxoglutarates use Ketoglutaric Acids | 
| Oxolinic Acid | 
| Oxonic Acid | 
| Oxoprolinase use Pyroglutamate Hydrolase | 
| Oxopropanal use Pyruvaldehyde | 
| Oxoquinolines use Quinolones | 
| Oxosteroids use Ketosteroids | 
| Oxosuccinates use Oxaloacetates | 
| Oxotremorine | 
| Oxprenolol | 
| Oxyamphetamine use p-Hydroxyamphetamine | 
| Oxybate Sodium use Sodium Oxybate | 
| Oxycephaly use Craniosynostoses | 
| Oxychlorochin use Hydroxychloroquine | 
| Oxychloroquine use Hydroxychloroquine | 
| Oxyclozanide | 
| Oxycodeinon use Oxycodone | 
| Oxycodone | 
| Oxydendron arboreum | 
| Oxyethylene Oxypropylene Polymer use Poloxalene | 
| Oxyfedrine | 
| Oxygen | 
| Oxygen Compounds | 
| Oxygen Consumption | 
| Oxygen Deficiency use Anoxia | 
| Oxygen Inhalation Therapy | 
| Oxygen Isotopes | 
| Oxygen Level | 
| Oxygen Partial Pressure Determination, Transcutaneous use Blood Gas Monitoring, Transcutaneous | 
| Oxygen Radicals use Reactive Oxygen Species | 
| Oxygen Radioisotopes | 
| Oxygen Requirement use Oxygen Consumption | 
| Oxygen Transfer | 
| Oxygen Transport use Oxygen Transfer | 
| Oxygenases | 
| Oxygenation | 
| Oxygenation, Extracorporeal Membrane use Extracorporeal Membrane Oxygenation | 
| Oxygenation, Hyperbaric use Hyperbaric Oxygenation | 
| Oxygenators | 
| Oxygenators, Membrane | 
| Oxygenium | 
| Oxyhemoglobins | 
| Oxylipins | 
| Oxymetazoline | 
| Oxymetholone | 
| Oxymorphone | 
| Oxyneurine use Betaine | 
| Oxyntic Cells use Parietal Cells, Gastric | 
| Oxyntomodulin | 
| Oxyphedrin use Oxyfedrine | 
| Oxyphenbutazone | 
| Oxyphenisatin use Oxyphenisatin Acetate | 
| Oxyphenisatin Acetate | 
| Oxyphenonium | 
| Oxyphenonium Bromide use Oxyphenonium | 
| Oxyphenonium Chloride use Oxyphenonium | 
| Oxyphenonium Iodide use Oxyphenonium | 
| Oxyphil Cells | 
| Oxyproline use Hydroxyproline | 
| Oxypurinol | 
| Oxyquinol use Oxyquinoline | 
| Oxyquinoline | 
| Oxytetracycline | 
| Oxythiamine | 
| Oxytocics | 
| Oxytocin | 
| Oxytocin Receptors use Receptors, Oxytocin | 
| Oxytocinase use Cystinyl Aminopeptidase | 
| Oxytricha | 
| Oxytropis | 
| Oxytropis lamberti | 
| Oxytropis lambertii use Aragallus lamberti | 
| Oxyuriasis | 
| Oxyurida | 
| Oxyurida Infections | 
| Oxyuris vermicularis use Enterobius | 
| Oxyuris vermicularis Infection use Enterobiasis | 
| Oxyuroidea | 
| Oxyvanadium use Vanadates | 
| Oyster Mushrooms use Pleurotus | 
| Oysters use Ostreidae | 
| Oysters, Eastern use Crassostrea | 
| Oysters, Pearl use Pinctada | 
| Oysters, True use Ostrea | 
| Ozena use Rhinitis, Atrophic | 
| Ozonation | 
| Ozone | 
| Ozone Depletion | 
| Ozone Hole use Ozone Depletion | 
| Ozone Layer | 
| Ozonosphere use Ozone Layer | 
| Ozonum use Oxygenium | 
| o,p-DDD use Mitotane | 
| o-Aminoazotoluene | 
| o-Aminobenzoic Acids use Anthranilic Acids | 
| o-Chlorobenzylidene Malonitrile use o-Chlorobenzylidenemalonitrile | 
| o-Chlorobenzylidenemalonitrile | 
| o-Dihydroxybenzenes use Catechols | 
| o-Phthalaldehyde | 
| omega-Aga-IVA use omega-Agatoxin IVA | 
| omega-Agatoxin IVA | 
| omega-Chloroacetophenone | 
| omega-Conotoxin GVIA | 
| omega-Conotoxins | 
| omega-Crystallins | 
| omega-N-Methylarginine | 
| ori Region use Replication Origin | 
| ortho,para-DDD use Mitotane | 
| ortho-Aminoazotoluene use o-Aminoazotoluene | 
| ortho-Aminobenzoic Acids use Anthranilic Acids | 
| ortho-Chlorobenzylidenemalonitrile use o-Chlorobenzylidenemalonitrile | 
| ortho-Dihydroxybenzenes use Catechols | 
| ortho-Phthalaldehyde use o-Phthalaldehyde |