complex skin structure with epithelial and mesenchymal origins which forms hair. (More? Hair Notes | Skin Notes)
named after the 2 authors of a paper that divides the 21 days of chicken embryo development into 46 defined stages. These were published in: Series of Embryonic Chicken Growth. J. Morphology, 88 49 - 92 (1951). (More? Chicken Embryo | Chicken Hamburger Hamilton Stages | Embryo Staging Systems)
haploid
(Greek, haploos = single) Having a single set of chromosomes as in mature germ/sex cells (egg, spermatazoa). Normally cells are diploid, containing 2 sets of chromosomes. (More? DNA Notes)
hard palate
the bony anterior portion of the palate formed by maxillary and palatine bones. The muscular posterior portion is the soft palate. (More? Head Notes)
colon recesses or sacculations caused by contractions of the teniae coli and circular muscle. (More? GIT Notes)
percentage of red blood cells in blood. (More? Blood Notes)
the process of blood cell formation. (More? Blood Notes)
(Hassall's corpuscles) Histological thymus structures that appear in fetal development and increase in number until puberty, then decreases. Named after Arthur Hill Hassall (1817-1894) a British physician and chemist. (More? Endocrine Notes - Thymus)
small canal in bone microstructure that conducts blood and other substances. Named after Clopton Havers (1650-1702) an English physician and anatomist. (More? Bone Notes)
an early developing organ which fuctions as a pump for blood in the embryo and adult. In the human the heart begins as a simple tube and undergoes complex folding and reorganization to form the 4 chambered heart. (More? Heart Notes)
hemangioblast
the common blood island progenitor cell which forms both hematopoietic (blood) and endothelial (blood vessel) cells. (More? Blood Notes Blood Vessels)
hemimelia
(Greek, hemi = half, melia = limb) limb abnormality with the absence of half a limb, as described in the original classical classification of limb deficiencies. (More? Limb Abnormalities - Classification)
(Greek, hepato = liver) relates to the liver and its associated structures. (More? Gastrointestinal Tract - Liver)
the liver excretory duct, joins with gall bladder cystic duct to form the common bile duct. (More? Gastrointestinal Tract - Liver | GIT Notes)
a peptide involved in iron homeostasis which is regulated by bone morphogenetic proteins (BMPs), cytokines belonging to the TGF- superfamily.
commercial name for an antibody that attaches itself to HER2 on breast cancer tumors, inhibiting the tumor's ability to grow. Approximately 15 - 25 % of breast cancer patients have a gene mutation known as HER2-positive.
general discription of protrusion of an organ through a weak spot in the surrounding tissue. In normal development, herniated midgut, describes the gastrointestinal tract growth outside the abdominal wall prior to body wall growth. In abnormal development, abnormal protrusion of organs in the diaphragm, abdominal or groin areas (hiatal hernias or inguinal hernias).
discription of the process of protrusion of an organ through a weak spot in the surrounding tissue. In normal development, herniated midgut, describes the gastrointestinal tract growth outside the abdominal wall prior to body wall growth. In abnormal development, abnormal protrusion of organs in the diaphragm, abdominal or groin areas (hiatal hernias or inguinal hernias). Occurs normally in the development of the gastrointestinal tract when the midgut is initially herniated at the umbilicus during embryonic development.
(Greek, heteros = other + trophe = nourishment) An organism that cannot derive energy from sunlight or from inorganic chemicals but must obtain energy by degrading organic molecules.
heterozygous
Having two different alleles for a single gene (in a diploid organism).
acronym for Haemophilus influenzae type b
vaccine. (More? Normal Development- Immunization)
high risk pregnancy
term relates to multiple pregnancies, previous pregnancy problem, health problem (either before or due to the pregnancy) and age (over 35 years). Examples of maternal health conditions leading to high risk pregnancy include: autoimmune disorders, cancer, diabetes, heart disease, high blood pressure, kidney problems and sexually transmitted diseases.
structural and functional differentiation of organs and tissues. (More? Fetal Development)
histology
(Greek, histos = web) One of a set of small, positively charged proteins that bind to DNA in eukaryotic cells. Their role is to "pack" DNA strands into a smaller volume to form the chromosome. (More? DNA Notes)
HIV
acronym for Human Immunodeficiency Virus.
placental villi macrophages of mesenchymal origin with potentially additional functions (remodeling, vasculogenesis, regulation of stromal water content) to their macrophage role. (More? Placental Notes)
homeostasis
(Greek, homeo = like, similar + stasis = standing) The process of achieving a relatively stable internal environment.
A mutation that causes the cells of an embryo to give rise to an inappropriate structure in the adult, for example, to legs instead of antennae. (More? Fly Notes)
The two matching chromosomes that align during meiosis I. (More? DNA Notes)
Having two copies of the same allele (in a diploid organism). (More? DNA Notes)
hormone
A substance, made and released by cells in a specific organ or structure, that moves throughout the organism and exerts specific effects on specific cells in other organs or structures.(More? Endocrine Notes)
Hox gene
from "homeo box
" a region of sequence required for DNA binding. Mammalian counterpart of a Drosophila homeo domain gene. (More? Molecular Notes)
acronym for Human papillomavirus, a group of more that 100 different viral strains. Detectable by pap smear (More? CDC STD Facts - Human papillomavirus | Medline Plus Human Papillomavirus | Human Menstrual Cycle- PapSmear)
acronym for Haematopoietic Stem Cell (note alternate spelling Hematopoietic) (More? Blood Notes)
human chorionic gonadotrophin
(hCG) hormone initially secreted by syncitiotrophoblasts supports corpus luteum which in turn supports endometrial lining and therefore maintaining pregnancy. (More? Week 2 Notes)
(HIV) the virus which leads to Acquired Immune Deficiency Syndrome (AIDS), a fatal disease that destroys the immune system's ability to fight off infection. HIV virus is capable of being transmitted from mother to fetus. (More? Abnormal Development - Viral Infection)
the first 8 weeks of human development following fertilization divided into 23 Carnegie stages and is the time of organogenesis. The following period defined as fetal development. (More? Embryo Stages)
Australian Government legal definition: "human embryo means a discrete entity that has arisen from either:
(a) the first mitotic division when fertilisation of a human oocyte by a human sperm is complete; or
(b) any other process that initiates organised development of a biological entity with a human nuclear genome or altered human nuclear genome that has the potential to develop up to, or beyond, the stage at which the primitive streak appears; and has not yet reached 8 weeks of development since the first mitotic division."
humoral immunity
(Latin, umor = fluid) the production of antibodies by the immune system that recognise foreign material to the body.
Hutchinson–Gilford Progeria Syndrome
(HGPS) a rare genetic disorder characterized by dramatic premature aging. It occurs due to a point mutation in the gene for nuclear lamin A (LA) protein which generates a mutant protein. (More?
Cao K, Capell BC, Erdos MR, Djabali K, Collins FS. A lamin A protein isoform overexpressed in Hutchinson-Gilford progeria syndrome interferes with mitosis in progeria and normal cells. Proc Natl Acad Sci U S A. 2007 Mar 14)
Hyaluronan
(hyaluronic acid or hyaluronate) glycosaminoglycan role in embryonic development and in joint fluid, space filling role in resisting compressive forces.
(More? Joint Development)
hydantoin syndrome
fetal disorder caused by exposure of a fetus to the anticonvulsant drug phenytoin (Dilantin) used in the treatment of epilepsy. (More? Abnormal Development - Drugs | Abnormal Development Notes | Medline Plus - phenytoin)
Hydrocele
(Greek, hydro = water, coele/koilia = cavity) a fluid-filled cavity of eiter testis or spermatic cord, where peritoneal fluid passes into a patent processus vaginalis. (More? Urogenital Notes)
hydrocephalus
(Greek, hydro = water + cephalus = brain) developmental abnormality, rostral neural tube defect anterior neuropore fails to close leadin to a fluid-filled space rather than normal brain development. (More? Neural Abnormalities)
hydrolysis
(Greek, hydro = water + lysis = breaking) Breaking the bond between two building blocks by adding a water molecule, reversing the dehydration-condensation reaction.
hydrophobic
(Greek, hydro = water + phobos = fear) Avoiding associations with water; nonpolar. The type of charge interaction which leads to the bilaminar structure of membranes where the nonpolar molecular "tails" face each other and polar "heads" are exposed to water.
hydrops fetalis
(Greek, hydro = water) accumulation of interstitial fluid (edematous) in the fetus resulting in utero or perinatal morbidity and mortality. The two main forms are immune (Rh incompatibility) or non-immune (disruption of fluid management). (More? Medline Plus - hydrops fetalis)
hydrosalpinx
(Greek, hydro = water + salpinx = trumpet) accumulation of interstitial fluid (edematous) in either one or both blocked uterine or fallopian (salpinx refers to the trumpet shape of the uterine tube) tubes due to a previous tubal infection. This blockage can impact upon maternal fertility and require IVF for reproduction. (More? ASRM - Hydrosalpinx Patient FactSheets)
a relatively new theory (yet to be tested) that suggests that first world disease like asthma, inflammatory bowel disease, multiple sclerosis, and others may be due in part to lifestyle and environmental changes that make us too "clean" for our environment.
high core body temperature shown in animal models to be a potent teratogen. (More? Abnormal Development- Hyperthermia)
hypochondroplasia
mild skeletal dysplasia, due to a mutation in gene encoding fibroblast growth factor receptor-3 (FGFR3), the same gene mutated in the more severe limb Achondroplasia. Genetically heterogeneous, with some cases caused by mutation in genes other than FGFR3. (More? Musculoskeletal Abnormalities | OMIM Hypochondroplasia | FGFR3)
hypohydrosis
diminished sweat gland function, perspiration. (More? Integumentary Development - Glands)
hypopharyngeal eminence
A narrow midline mesenchymal exension lying within the curve of the pharynx. Fusion of 3rd pharyngeal arches, precursor of root of tongue. (More? Head Notes)
a decreased amount of hair. (More? Integumentary Development - Hair)
alternative name for the pituitary gland. (More? Pituitary Notes |Endocrine Notes)
hypospadia
most common penis abnormality (1 in 300) resulting from a failure of male urogenital folds to fuse in various regions and are therefore classified by the
location of the opening (meatus). (More? Genital Abnormalities - Hypospadia | Genital Notes)
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Search the NIH Medlineplus Medical Dictionary Type the word that you would like to find. If unsure of spelling, type the first few letters, followed by an asterisk(*). |
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Use this page to access brief definitions of specific alphabetically listed 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 Glossary List: Texts listed on page 1 Reading of each notes section, Department of Anatomy Publications, WWW resources from NCBI, AMA (USA), Office of Rare Diseases (USA), PubMed Medline Dictionaries, MSDS, Merck Manual home edn., NHMRC (Australia). 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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