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Glossary Links
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nanog
- Homeodomain-containing transcription factor involved in maintaining embryonic stem (ES) cell self-renewal. Name is derived from Celtic "Tir Na Nog" a mythologic Celtic land of the ever young. Also expressed in implanting embryos and for the early proliferation and survival of primordial germ cells (PGCs).
- (More? OMIM NANOG | Molecular Factors- Nanog | PMID19906868 | PMID20539761)
nanoparticles
- Nanomaterials are a new technology used commercially in many different areas (cosmetics, therapeutic agents and household products). No safety regulations are yet in place for the use. Silver nanoparticles (Ag-np) are used for their antimicrobial potential and have been shown to have an anti-proliferative activity.
- (More? PMID:19761582)
nail-patella syndrome
- (NPS) rare (1/50,000) Autosomal dominant disorder characterized by hypoplastic or absent patellae, dystrophic nails, dysplasia of the elbows and iliac horns. Potentially due to mutations in LMX1B, a LIM-homeodomain transcription protein.
- (More? OMIM nail-patella syndrome | LMX1B)
nasal placode
- (olfactory placode) (placode - Greek, plax = "plate" or "scale", eidos = shape or form) Cranial region of thickened ectoderm that will generate the sensory olfactory epithelium of the nose required for smell.
necrosis
- (Greek, nekros = corpse) Pathological cell death from extrinsic injury. Cell lyses releasing cytoplasmic contents which may also have a role in initiating an inflammatory response.
- (See also apoptosis)
necrotizing enterocolitis
- (Greek, nekros = corpse) Gastrointestinal tract pathology occurring postnatally in mainly in premature and low birth weight infants (1 in 2,000 - 4,000 births). The underdeveloped gastointestinal tract appears to be susceptible to bacteria, normally found within the tract, to spread widely to other regions where they damage the tract wall and may enter the bloodstream. The condition only occurs after postnatal bacterial colonization and not in the sterile intrauterine microenvironment prior to birth. Pathological cell death from extrinsic injury, cell lyses releasing cytoplasmic contents which may also have a role in initiating an inflammatory response.
- (More? Gastrointestinal Tract Abnormalities | Neonatal Development | Medline Plus - Necrotizing Enterocolitis)
Neisseria gonorrhoeae
- A gram-negative bacteria which causes the disease Gonorrhea, which is a sexually transmitted disease (STD).
- (More? Abnormal Development - Bacterial)
nebenkern
- (German, nebenkern = subsidiary nucleus) A mitochondrial aggregate formed during developemnt of the Drosophila spermatazoa. The individual mitochondria fuse into two giant mitochondria arranged in a sphere of many layers of "onion-like" wrapped mitochondrial membranes. This process appears to only occur in some insect spermatogenesis.
- (More? Fly Development | Meiosis | Spermatozoa Development)
nematode
- (roundworm) A phylum of small worms, with the species Caenorhabditis elegans (C.Elegans) used in developmental, genetic and neural studies.
- (More? Worm Development)
neonatal
- Term used in relation to the newborn infant and up to four weeks old.
neonatal diabetes
- Diabetes mellitus that has been diagnosed within the first 6 months of life. There are two main clinical subtypes: persistent, permanent neonatal diabetes (PNDM) and remitting and frequently relapsing, transient neonatal diabetes (TNDM). Permanent neonatal diabetes has been shown to result from mutations in the preproinsulin (INS) gene.
neonatal bacterial sepsis
- (neonatal sepsis) A newborn infection by microorganisms, located mainly in the maternal genital tract, either by transplacental infection or an ascending infection or at delivery. Treated with an antibacterial drug (penicillin, ampicillin, gentamicin, cefotoxine, etc.) and given systemically (intravenous or intramuscular). Note that antibiotics are also given to infants for reasons other than neonatal sepsis.
neonatal intensive care unit
- (NICU) A hospital facility or unit staffed and equipped to provide continuous mechanical ventilatory support at any time during the infant’s hospital stay following delivery.
neonatal sepsis
- (neonatal bacterial sepsis) A newborn infection by microorganisms, located mainly in the maternal genital tract, either by transplacental infection or an ascending infection or at delivery. Treated with an antibacterial drug (penicillin, ampicillin, gentamicin, cefotoxine, etc.) and given systemically (intravenous or intramuscular). Note that antibiotics are also given to infants for reasons other than neonatal sepsis.
neoplastic rest
- In kidney development, a neoplastic rest can develop under either genetic or epigenetic influence from a hyperplastic rest, originating from an embryonic blastema cell. Normally the majority of nephrogenic rests either regress or become dormant.
nephrin
- Structural protein of the kidney nephron, forming a major component of the glomerular slit diaphragm. Also acts late in the process of podocyte differentiation as a signaling molecule influencing foot process formation and the maintenance of podocyte integrity.
- (More? Lecture - Kidney Development | Urogenital Notes)
nephroblastoma
- A childhood kidney cancer see Wilm's tumour
nephrocan
- A secreted small leucine-rich repeat proteoglycan/protein expressed during development in the kidney and pylorus of the gastrointestinal tract and may act through inhibition of TGF-beta signaling.
- (More? :(More? 2009 Lecture - Kidney Development | PMID: 16990280 | PMID: 19877272)
nephrogenic rest
- A kidney term used to describe the embryonic blastema cells which persist and under either genetic or epigenetic can change to become a neoplastic rest. These neoplastic rests can develop postnatally as a benign form (adenomatous rest) or a malignant Wilm's tumour form. The rests are further characterised by the time of generation leading to different anatomical kidney locations: early intralobar nephrogenic rests (within the renal lobe) and late pelilobar nephrogenic rests (periphery of the renal lobe).
- (More? Wilm's tumour | Urogenital Abnormalities | Urogenital Notes)
nephron
- (Greek, nephros = kidney) The functional unit of the kidney.
- (More? Lecture - Kidney Development | Urogenital Notes)
nephros
- (Greek, nephros = kidney) Term used to describe features associated with the kidney. (pronephros, mesonephros, metanephros, nephric, nephron, nephroblastoma)
- (More? Lecture - Kidney Development | Urogenital Notes)
nestorone
- A synthetic progesterone potentially used in postmenopausal women (with an intact uterus in combination with estrogen as hormone-replacement therapy (HRT). (Other Progestins: levonorgestrel, 3-keto-desogestrel, dienogest, drospirenone, Nestorone and nomegestrol acetate) Trimegestone and Nestorone are currently the most potent fourth-generation progestins with no androgenic or estrogenic actions.
- (More? Human Menstrual Cycle)
neuralation
- The general term used to describe the early formation of the nervous system. It is often used to describe the early events of differentiation of the central ectoderm region to form the neural plate, then neural groove, then neural tube. The nervous system includes the central nervous system (brain and spinal cord) from the neural tube and the peripheral nervous system (peripheral sensory and sympathetic ganglia) from neural crest. In humans, early neuralation begins in week 3 and continues through week 4.
- (More? 2009 Lecture - Ectoderm Development | Neural Notes | Neural Crest Notes | Development Week by Week)
neural crest
- A cell region at edge of neural plate, then atop the neural folds, that remains outside and initially dorsal to the neural tube when it forms. These paired dorsal lateral streaks of cells migrate throughout the embryo and can differentiate into many different cell types (= pluripotential). Those that remain on the dorsal neural tube form the sensory spinal ganglia (DRG), those that migrate ventrally form the sympatheitic ganglia. Neural crest cells also migrate into the somites and regions throught the entire embryo.
neural folds
- The central region of the trilaminar embryo ectoderm called the neural plate region folds dorsally, generating two neural folds, which later fuse to form the neural tube. The mid-line depression between the two folds is described as the neural groove. In humans at approximately day 18-19 post-fertilization to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
- Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
neural groove
- The second stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate. This epithelium will fold dorsally, beginning in humans at approximately day 18-19 post-fertilization to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
- Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
neural plate
- The first stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate. This epithelium will fold dorsally to form the neural groove, which then fuses to form an initially open at either end hollow neural tube. The neural tube forms the central nervous system (brain and spinal cord).
- Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
neural stem cell
- (NSC) A stem cell within the central nervous system (CNS) that can proliferate indefinitely and give rise to either neurons, astrocytes, and oligodendrocytes.
- (More? Neural Stem Cell Notes | Neural Notes | Stem Cell Notes)
neural stem cell niche
- Locations within the nervous system that multipotent stem cells reside and participate in specialized microenvironments that support cell self-renewal and differentiation.
- (More? Neural Stem Cell Notes | Neural Notes | Stem Cell Notes)
neural tube
- The third stage in early development of the central nervous system. In the trilaminar embryo (ectoderm, mesoderm, endoderm) the central region of the ectoderm (in the midline above the mesodermal notochord) initially forms a columnar epithelium described as the neural plate . This epithelium will fold dorsally to form the neural groove, which then fuses to form initially a hollow tube open at either end (neuropores). The neural tube forms the central nervous system (brain and spinal cord).
- Developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord)
neuroblastoma
- A tumour derived from neural crest cells.
- (More? Neural Crest - Abnormalities)
neurocysticercosis
- (NCC) Clinical term for a zoonotic parasitic disease caused by infection with the larval stage of Taenia solium (pork tapeworm) infestation of the central nervous system. The ventricle infestation is due to active passage of hexacanthous embryo through the cappilaries of the choroid plexus.
neuroenteric canal
- The canal or opening existing early in trilaminar embryo development that provides transient communication between the amnion and the yolk sac. Canal forms as part of axial process development, the precursor to the notochord.
- (More? Neural System Development)
neurogenesis
- The process of formation of the neural system. Early neurogenesis begins with segregation of the neural plate from the ectoderm of the trilaminar embryo by folding to form initially the neural groove, which then fuses to form the neural tube (the central nervous system progenitor, brain and spinal cord) and associated neural crest. Later neurogenesis in the central nervous system is the proliferation of ventricular neural stem cells, differentiation, migration and lamination of the developing neural system.
- Early developmental sequence: neural plate -> (day 18-19) neural groove -> neural tube -> Central Nervous System (brain and spinal cord).
- (More? Neural System Development)
neurogenin-3
- (NEUROG3) Gene expressed in endocrine progenitor cells (including pancrea islet cells) and required for endocrine cell development in pancreas and intestine. Mutation in this gene depletes intestinal enteroendocrine cells resulting in malabsorptive diarrhea.
neuron
- (neurone) The cell forming the unit basis of the nervous system (both central and peripheral) capable of generating an action potential and releasing neurotransmitter. There are many different types of neuronal cells.
neuropilin
- (NRP1, NRP2) A transmembrane receptor acting as a coreceptor to a tyrosine kinase receptor for both vascular endothelial growth factor (VEGF) and semaphorin.
- (More? OMIM)
neuropore
- The initial two openings at either end of hollow neural tube called the cranial (rostral, anterior) and caudal (posterior). The cranial neuropore closes (day 25) approx. 2 days (human) before caudal. The developmental abnormality classed as Neural Tube Defects (NTDs) can be due to failure of these two neuropores to developmentally close and has been associated with low dietary folic acid.
- (More? 2009 Lecture - Ectoderm Development | Neural Notes | Neural Abnormalities | Folic Acid and Neural Tube Defects)
neutrophil
- (neutrophil granulocytes) A white blood cell granulocyte that has a central role in the inflammatory process, invade sites of infection in response to growth factors. Cell nucleus has a characteristic lobed appearance (3-5 lobes), the number of lobes increases with cell age. During the menstrual cycle, a cyclic change in neutrophil cell number in the endometrium is shown by vaginal smear.
nicotine
- A natural alkaloid ingredient in tobacco leaves, where it provides protection by acting as a botanical insecticide. There is an association between physical defects among newborns and maternal smoking tobacco during pregnancy.
- (More? Abnormal Development Smoking | Smoking Workshop)
nicotinamide
- The amide of vitamin B3 and is the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD+) and has been used in humans for the treatment of diabetes and bullous pemphigoid. Identified in mice as a potential protective agent against ethanol-induced cell death in the developing brain by inhibiting ethanol-induced caspase-3 activation.
nidation
- Term used to clinically describe implantation within the uterus.
- (More? Week 2 Notes)
Nitabuch's layer
- (fibrinoid layer) The layer formed at maternal/fetal interface during placentation and is thought to act to prevent excessively deep conceptus implantation. Fibrin-type fibrinoid (maternal blood-clot product) and matrix-type fibrinoid (secreted by invasive extravillous trophoblast cells).
- (More? Placenta Development)
Nogo
- (Reticulon 4, RTN4, Neurite Growth Inhibitor 220) One of several myelin-associated proteins with inhibitory effects for neuronal neurite outgrowth. Nogo exists as 3 splice transcript variants (NOGO-A, NOGO-B and NOGO-C) which are differentially expressed in the developing central nervous system. Also associated with autoimmune demyelination, shown in models of multiple sclerosis (MS) such as experimental autoimmune encephalomyelitis (EAE).
- (More? Nogo-A | Neural Notes | OMIM - Reticulon 4)
Nogo-A
- A myelin-associated protein which can inhibit neurite outgrowth and prevent regeneration in the adult central nervous system. Secreted by oligodendrocytes in the central nervous system, but not by Schwann cells in the peripheral nervous system.
- (More? Neural Notes | OMIM - Reticulon 4)
nondisjunction
- Genetics term describing the failure of any paired chromosomes to separate (disjoin) during cell division. This leads to an uneven distribution of chromosomes to daughter cells, both chromosomes go to one daughter cell and none to the other. In humans, the most common form of nondisjunction occurs in autosomal chromosome trisomies, trisomy 21 (Down's syndrome) and trisomy 18.
- (More? Trisomy 21 | Trisomy 18)
nonvertex presentation
- Birth term referring to the presentation (fetal presentation) of a part of the infant’s body other than the upper and back part of the infant’s head to the birth canal.
- (More? Birth)
nosocomial
- An infection acquired with medical treatment, generally associated with hospitals. Some forms of acquired infections may impact on fetal development either directly, by transmission to the fetus, or indirectly through maternal effects such as fever.
- (More? Abnormal Development)
notch
- A cell surface single-pass transmembrane receptor family (1-4) required for asymmetric cell division. Acts as a receptor for Jagged (1,2) and Delta-like (1,3,4) proteins and also interacts with a negative regulator (Numb) which is down-regulated by notch. Asymmetry of cell division allows generation of distinct progeny from a single cell division required in many developmental processes including neurogenesis.
- (More? OMIM - NOTCH | OMIM - NUMB | PMID19799767)
notch-regulated ankyrin-repeat protein
- (Nrarp) A protein downstream target of the Notch signaling pathway. Nrarp is a 114 amino acid protein with a carboxy-terminal domain containing two ankyrin-repeat motifs. This protein has been identified as a component of somitogenesis, expressed in presomitic mesoderm, and T cell development, from hematopoietic stem cells.
notochord
- (axial mesoderm) The rod of cells lying in the midline of the trilaminar embryo mesoderm layer ventral to the neural tube. Thought to have at least 2 early roles in development and later roles in patterning surrounding tissues. 1. Mechanical, influencing the folding of the early embryo; 2. Morphogenic, secreting sonic hedgehog a protein which regulates the development of surrounding tissues (neural plate, somites, endoderm and other organs). In humans, the notochord forms in week 3 and is eventually lost during the formation of the vertebral column.
- (More? Notochord | Development Animation - Notochord | Musculoskeletal | Neural | Sonic hedgehog)
Non-Hodgkin's lymphoma
- (NHL) A type of cancer where the cause is unknowm and may develop in people with suppressed immune system. Treatment may cause premature ovarian failure. A recent study has shown CHOP therapy (cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, vincristine 1.4 mg/m2 (maximum 2 mg) and prednisone 100 mg/day for 5 days) does not affect the ovarian function or fertility.
- (More? Medline Encyclopedia | PMID: 15817583)
Nrarp
- Acronym for notch-regulated ankyrin-repeat protein, which is a downstream target of the Notch signaling pathway. Nrarp is a 114 amino acid protein with a carboxy-terminal domain containing two ankyrin-repeat motifs. This protein has been identified as a component of somitogenesis, expressed in presomitic mesoderm, and T cell development, from hematopoietic stem cells.
NRT
- An acronym for Nicotine Replacement Therapy, a method of replacing cigarette nicotine by either nicotine transdermal patches, nicotine gum, nicotine lozenges or nicotine inhalers.
- (More? Abnormal Development Smoking | Smoking Workshop)
nucleus pulposus
- Anatomical core within the intervertebral disc of the vertebral column. Apparently the only adult structure formed from the embryonic notochord. The nucleus pulposus is a gel-like structure surrounded by a thick fibrous tissue and fibrocartilage forming the annulus fibrosus, formed embryonically from the sclerotome.
numb
- A membrane-associated protein (also Numblike) involved in asymmetric cell division along with notch. Acts as a negative regulator of notch which can also down-regulate numb expression. Asymmetry of cell division allows generation of distinct progeny from a single cell division required in many developmental processes including neurogenesis.
- (More? JCB - Notch and Numb | OMIM - NUMB | | OMIM - NUMBL | OMIM - NOTCH)
Glossary Comments
Use this page to access brief definitions of specific embryology terms. Additional information can be accessed from links listed at the end of each definition. Glossary from the UNSW Embryology program compiled and written by Dr Mark Hill. Reference material used in preparing this glossary list includes: texts listed on page 1 "Reading" of each notes section, Department of Anatomy Publications, WWW resources from NCBI, NIH, OMIM, NHMRC (Australia), AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn. and WHO ART terminology (2009).
These notes are for Educational Purposes Only Please email Dr Mark Hill if you wish to make a comment about this current project.
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Cite this page: Hill, M.A. (2024, June 6) Embryology N. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/N
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