UNSW Embryology

Glossary R

© Dr Mark Hill (2008)

Acknowledgements

raphé

the line of fusion of the urogenital folds along the urethra and scrotum in male external genitalia (More? Urogenital Notes)

Rathke's pouch

- fold in roof of pharynx forming anterior pituitary (adenohypophysis) and pars intermedia. Named after German embryologist and anatomist Martin Heinrich Rathke (1793 — 1860). (More? Pituitary Notes | Endocrine Notes | Martin Heinrich Rathke)

reductive division

meiosis where diploid DNA content becomes haploid.

Reichert's cartilage

neural crest froming cartilage of the 2nd pharyngeal arch. (More? Head Notes)

relaxin

reproductive hormone involved in uterine relaxation (some species), reproductive tissue growth, connective tissue remodeling (collagen), cardiovascular, renal system, and brain. Relaxin receptor is G-protein-coupled receptor (relaxin family peptide receptors 1 - 4, RXFP1-4). (More? Urogenital Notes)

renal

used in relation to the kidney (More? Urogenital Notes)

repolarization

in relation to the heart, repolarization is a term used to describe the relaxation after each cardiac contraction which is controlled by a gradient of ion channels. (More?Heart Notes)

respiratory

used in relation to breathing (in and out). Anatomically used to describe the lungs, air pathways and associated muscles. In cell biology used in relation to mitochondrial use of oxygen to produce energy and carbon dioxide waste. (More? Respiratory Notes)

RESOLVE

A national, nonprofit consumer organization offering education, advocacy, and support to those experiencing infertility. Services include a national HelpLine, quarterly newsletter, extensive literature list, member-to-member contact systems, and local support groups through a network of over 50 chapters nationwide.

retained products of conception

where part of the placenta or fetal membranes remains within the uterus, often associated with early fetal loss in the first trimester (previously called incomplete abortion).

rete ovarii

group of epithelial tubules located at the hilum of the ovary possibly mesonephric origin. (More? Urogenital Notes)

rete testis

duct (epithelial tubules) conduction system for spermatazoa embedded within the mediastinum (connective tissue) located in the center of the testis (male gonad) derived from the mesonephric duct, and allow spermatazoa to travel from the seminiferous tubules to the vasa efferentia. (Spermatozoa Duct Pathway: seminiferous tubule → straight tubule → rete testis → ductuli efferentes → ductus epididymidis → ductus deferens) (More? Spermatogenesis | Urogenital Notes)

retinal waves

a form of coordinated spontaneous activity that occurs in the developing retina. These waves of electrical activity (action potentials) along with EphA/ephrin-A signaling are thought to have a role in establishing the initial retinotopic map by correlating/coordinating the activity of neighbouring retinal ganglion cells. (More? Vision Notes)

Rh factor

protein on surface of red blood cells in some blood types (Rh+) and absent in others (Rh-). Can cause erythroblastosis fetalis in second pregnancy if fetal/maternal blood of opposite groups mix on first pregnancy.

Rho1

small GTPase of the Rho subfamily (Rho, Rac and Cdc42) acts as regulatory switch for actin cytoskeleton. In development, activated in epithelial cells for invagination. (More? Developmental Mechanisms)

rhombencephalon

(Greek rhombos = rhomboid, enkephalos = brain) hindbrain, at the early (3 primary vesicle) stage of brain development, this is the most caudal vesicle. At the 5 secondary vesicle stage of brain development this then forms both the metencephalon and the myeloncephalon. Finally forming the adult structures of cerebellum, pons and medulla. (More? Neural Notes)

rhombomere

segmentation of the hindbrain (rhombencephalon) reflects segemental (rostro/caudal) expresion of Hox gene. (More? Neural Notes)

ricin

a highly potent toxin produced by castor beans, it contains a ribotoxic A chain (RTA) and a cell-binding B chain.

roof plate thin dorsal region of neural tube. (More? Neural Notes)

RU 486

RU 486 (or Mifepristone) is a steroid hormone similar in structure to the natural hormone progesterone, which is used as a birth control drug. (More? RU486)

rubella

(Latin, rubella = little red) also known as "german measles" (due to early citation in German medical literature) is a virus that crosses the placenta from infected mothers and leads to major developmental defects in different developing systems. (More? Abnormal Development - Rubella Virus | Abnormal Development - Virus)

Alphabetical Links

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External Resources

Comments

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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