UNSW Embryology

Glossary I

ICSH

Acronym for [#interstitial_cell_stimulating_hormone Interstitial Cell Stimulating Hormone] an anterior pituitary hormone.

(More? [#interstitial_cell_stimulating_hormone Interstitial Cell Stimulating Hormone])

idiopathic

( Greek, idios = one's own + pathos = suffering) Term used clinically to describe a condition which is unexplained (obscure, unknown cause) or has no other clinical or biochemical associated abnormality.

(More? Abnormal Development)

ICSI

An acronym for ===I===ntra===C===ytoplasmic ===S===perm ===I===njection, A procedure in which a single sperm is injected directly into an egg; this procedure is most commonly used to overcome male infertility problems.

(More? Week 1 - In Vitro Fertilization | Week 1 - Spermatogenesis)

IHBD

An acronym for [#intrahepatic_bile_ducts intrahepatic bile duct]

ileum

Third part of small intestine lying between the jejunum and large intestine. (More? Gastrointestinal Tract Notes)

implantation

The term used to describe process of attachment and invasion of the [U.htm#uterus uterus] endometrium by the blastocyst (conceptus). Abnormal implantation is where this process does not occur in the body of the [U.htm#uterus uterus] (ectopic) or where the placenta forms incorrectly.

(More? Week 2 - Implantation | Week 2 Abnormalities)

incomplete abortion

previous term for [R.htm#retained_products_of_conception retained products of conception] where part of the placenta or fetal membranes remains within the [U.htm#uterus uterus].

incus

One of 3 bones of the middle ear (stapes-malleus-incus) converts mechanical vibration into fluid movement within cochlea.

(More? Hearing Notes | Middle Ear)

induced abortion

(therapeutic abortion) A surgical, pharmaceutical or other medical procedure used to end a pregnancy.

induced pluripotent stem cell

(IPS cell) A reprogrammed adult stem cell to form an embryonic stem cell, from which tissues or whole animals can develop.

(More? Adult Stem Cells | Stem Cells)

induction

Developmentally, the term is used to describe the process by which one cell population influences the development of neighbouring cells.

Clinically or medically, the term is used to describe the process of artificially inducing labour.

(More? Birth Notes)

infantile hemangioma

(IH) One of the most common skin birthmarks appearing as a benign vascular neoplasm, not noted at birth but developing in the neonate and later postnatally. There are several known risk factors: female sex, white non-Hispanic race/ethnicity, and preterm birth. Though described as benign, a recent study has statistically linked these skin anomalies with low birth weight (LBW).

(More? Integumentary Development - Abnormalities | Abnormal Development | Birth - Low Birth Weight | PMID: 18940356)

infectious disease

(contagious disease) A bacterial, viral or fungal organism that is transferred from one organism to another by four main methods of transmission (contact, vehicular, airborne or vector). Contagiousness refers to the ease of transmission of the infective agent.

(More? Abnormal Development)

inferior

Anatomical term meaning below, beneath or lying below, a relative anatomical term.

infertility

Not fertile, unable to produce offspring.

(More? Week 1 Abnormalities)

infundibulum

The funnel-shaped initial segment of uterine tube (oviduct or Fallopian tube) opening into peritoneal cavity and connected to the ampulla. The peritoneal opening sitting over the ovary.

(More? Week 1 - Oogenesis | Genital System - Female)

inguinal canal

The anatomical pathway for male testes descent from the abdominal cavity (fetal) into the scrotum.

(More? Genital System - Male | Genital Notes - Gonadal Descent)

Inhibin A

A glycoprotein hormone is secreted by the corpus luteum and placenta and regulates pituitary follicle stimulating hormone (FSH). The hormone acts in negative feedback regulation of FSH during pregnancy. Measurement of Inhibin A levels is also used as a second-trimester maternal serum marker for Down syndrome.

Inhibin B

A glycoprotein hormone is secreted by early antral follicles during the luteo-follicular transition of the menstrual cycle and regulates pituitary follicle stimulating hormone (FSH).. In humans during the early follicular phase, high inhibin B concentrations allow the selection of a single follicle by decreasing the FSH serum levels.

inner cell mass

In a mammalian embryo, a small group of cells within a blastocyst that will eventually grow into the embryo itself and subsequently into the adult. The remainder of cells that form the wall are the [T.htm#trophoblast trophoblast] cells.

(More? Week 1 Notes | Week 2 Notes)

insulin

A protein hormone, produced by specialized cells of the pancreas, that regulates glucose uptake; a signal for the absorptive state; promotes the synthesis of glycogen and inhibits its breakdown.

(More? Endocrine Development - Pancreas)

integument

(Latin, in = on, tegmen = a roof, covering) term used to describe the skin and its associated structures.

(More? Skin Notes)

interatrial septum

(IAS) The wall (septum) that develops between the two atria in heart (cardiac) development. In the embryo, this septum develops as a sequence of mesenchymal structures bridging the left and right atrial opening (primary atrial foramen) forming a primary and secondary atrial septum.

(More? Heart Notes)

interferons

A cytokine that interferes non-specifically with the reproduction of viruses.

interferon-alpha

(IFNalpha) cytokine used to treat several malignant and nonmalignant diseases, especially hepatitis C.

interfollicular epidermis

(IFE) Term used to describe regions of the cellular (keratinocytes) outer layer of skin, the epidermis, lying between hair follicles. The keratinocyte epidermal cells are an ectoderm derived tissue.

(More? Integumentary Development)

interleukins

internal auditory meatus

(internal acoustic meatus, IAM) An anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur.

(More? Inner Ear - Internal Auditory Meatus | Hearing Development - Inner Ear | Sensory Development - Hearing)

interphase

The part of the cell cycle in which the chromosomes are not condensed and the cytoplasm is not dividing.

interstitial cell

(Leydig cell) Alternative name for [L.htm#Leydig Leydig cell] found within the male gonad (testis). A cell that is involved in androgen (testosterone) production.

(More? Genital System - Male | Endocrine Development - Gonads)

interstitial cells of Cajal

(ICC) Neural cells located in the gastrointestinal tract (enteric nervous system) located within the smooth muscle wall (tunica muscularis) that act as electrical pacemakers to coordinate muscular slow wave contraction propagation. There is some evidence which suggests rather than neural crest, that these cells are mesenchymal (like gastrointestinal smooth muscle) in origin. There is also species variablity in plexus formation. In humans, interstitial cells of Cajal (ICC) myenteric plexus (ICC-MP) forms first, then intramuscular (ICC-IM) and deep muscular plexus (ICC-DMP) which are not fully differentiated at birth.

(More? Gastrointestinal Tract Notes)

interstitial cell stimulating hormone

(ICSH, gonadotropin, lutropin, Interstitial Cell Stimulating Hormone, ICSH) Glycoprotein hormone releasd from anterior pituitary hormone that acts on the gonad and has a role in male and female reproduction. In male, stimulates testis interstital cell (Leydig cell) production of testosterone. In female, increase in concentration during the menstrual cycle triggers ovulation (release of the oocyte).

(More? Endocrine Development - Gonads | Genital System - Male)

interstitial growth

The form of cartilage growth which occurs from within, leading to an increase of cartilage mass. The second form of cartilage growth is appositional, occurring on the surface.

(More? Musculoskeletal Development)

interventricular septum

(IVS) The wall (septum) that develops between the two ventricles in heart (cardiac) development. In the embryo, this septum develops as a sequence of mesenchymal structures bridging the left and right ventricular opening forming a membranous then muscular septum.

(More? Heart Notes)

interzone

A term used to describe in development of the musculoskeletal joint, the initial site of higher cell density found at the position of the future skeletal joint.

(More? Joint Development)

intestine

(bowel) Term used to describe the midgut and hindgut portion of the gastrointestinal tract running from after the stomach to the anus. This can also be anatomically subdivided into the small intestine (small bowel) and the large intestine (large bowel).

(More? Gastrointestinal Tract Notes)

intestinal aganglionosis

(Hirschsprung's Disease, aganglionic colon, megacolon, congenital aganglionic megacolon) Gastrointestinal tract abnormality due to a lack of enteric nervous system (neural ganglia) in the intestinal tract responsible for gastric motility (peristalsis). In general, its severity is dependent upon the amount of the GIT that lacks intrinsic ganglia, due to an earlier developmental lack of neural crest migration into those segments. Historically, Hirschsprung's disease takes its name from Dr Harald Hirschsprung (1830-1916) a Danish pediatrician (of German extraction).

(More? Gastrointestinal Tract Abnormalities | Neural Crest Abnormalities)

intestinal immune system

System consists of gastrointestinal tract functional regions and cells including: Peyer's patches, isolated lymphoid follicles, cryptopatches and mesenteric lymph nodes.

(More? Gastrointestinal Tract Notes | Immune Notes)

intracytoplasmic sperm injection

(ICSI) A procedure in which a single sperm is injected directly into an egg; this procedure is most commonly used to overcome male infertility problems.

(More? Week 1 - In Vitro Fertilization | Week 1 - Spermatogenesis)

intraembryonic coelom

The "horseshoe-shaped" space (cavity) that forms initially in the third week of development in the lateral plate mesoderm that will eventually form the 3 main body cavities: pericardial, pleural, peritoneal. The intraembryonic coelom communicates transiently with the extraembryonic coelom.

(More? Coelom Notes | Week 3 Notes)

intraflagellar transport

(IFT) process by which cilia containing microtubules are formed on cells. Recent research has shown an important roles for cell cilia in different systems during embryonic development.

intramembranous ossification

The term used to describe the process of replacement of a membranous mesenchyme with bone by osteoblasts (bone-forming cells). Mesenchymal cells (osteoprogenitor cells) differentiate into osteoblasts at the initial sites of ossification (ossification centre). Occurs in skull (jaw, cranial vault) and clavicle. The majority of the skeleton is formed by ann alternative process of bone formation on a cartilaginous template, [E.htm#=endochondral_ossification =endochondral ossification].

(More? Musculoskeletal Development - Bone | Musculoskeletal Notes)

intrahepatic bile ducts

(IHBDs) transport bile secreted from hepatocytes to the hepatic duct. The cells that line the IHBD are biliary epithelial cells generated from bipotent hepatoblasts around the portal vein.

(More? GIT Notes - Liver | GIT Notes - Gall Bladder)

intrapartum

The time in between the beginning of labor and delivery at birth (parturition).

(More? Birth Notes)

intrauterine

Term means lying within the [U.htm#uterus uterus].

intrauterine growth restriction

(IUGR) Term used to descibe clinically a fetus that has not reached its growth potential because of genetic or environmental factors. Abnormal development measured as less than 10th percentile for gestational age, not easy to detect before 32 weeks. This poor fetal growth can have fetal, placental or maternal causes.

in vitro

(Latin, vitro = glass) In a test tube, used to describe any process that does not occur in its natural environment (in vivo). In development, often associated with In Vitro Fertilization (IVF).

in vitro fertilization

IVF, a procedure that involves removing eggs from a woman's ovaries and fertilizing them outside her body. The resulting embryos are then transferred back into the woman's [U.htm#uterus uterus] through the cervix.

(More? Week 1 - In Vitro Fertilization | Week 1 - Fertilization)

in vivo

(Latin, vivo = life) Term used describe any process that occurs in its natural (normal) environment.

in vivo fertilization

The natural biological mechaism of [F.htm#fertilization fertilization] that occurs within the body.

(More? Week 1 - In Vivo Fertilization | Week 1 - Fertilization)

inotropes

Drugs that increase the force of cardiac contraction by acting on the autonomic nervous system.

(More? Heart Notes)

Iodine

(Greek, ioeides = violet) An element named for the color of its vapour. It is an essential element required for the synthesis of thyroid hormone, which in turn is required for normal neural development.

(More? Abnormal Development - Iodine Deficiency)

ischemia

A lack of oxygen in a tissue or organ due to decreasd blood flow by any mechanism (obstruction, narrowing or damage to blood vessels). Leads to hypoxia in the tissue.

islets of Langerhans

A small cell clusters spread throughout the exocrine pancreas with an endocrine (hormonal) function.

(More? Endocrine Development - Pancreas)

isthmus

(Greek, isthmos = a narrow passage, a land-bridge, a connecting band) A term used to describe anatomical structures with a similar physical structure. Uterine isthmus is the region between the uterine body (corpus) and the cervix.

IUGR

An acronym for ===i===ntra===u===terine ===g===rowth ===r===estriction=== or r===etardation, < 10th percentile for gestational age, not easy to detect before 32 weeks

(More? Abnormal Notes IUGR | Fetal Programming Hypothesis)

IUI-donor

An acronym for ===i===ntra-===u===terine ===i===nsemination using donated sperm.

(More? Week 1 - In Vitro Fertilization)

IVF

Acronym for In Vitro Fertilization, a procedure that involves medical intervention in the normal [F.htm#fertilization fertilization] process. There are currently many different ways in which [F.htm#fertilization fertilization] may occur using these clinical techniques. For example, removing eggs from a woman's ovaries, fertilizing them outside her body, then transferring back into the woman's [U.htm#uterus uterus] through the cervix.

(More? Week 1 - In Vitro Fertilization | Week 1 Notes)Created: 01.06.1997Updated: 24.07.2009 UNSW CRICOS Provider Code No. 00098G