Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «M»:
MEDVAC: Acronym for medical evacuation. MEDVAC typically refers to a team that is organized with the skills for the purpose of proper medical evacuation in situations of emergency....
MEF2A: A transcription factor that participates in vascular development. MEF2A is a member of the myocyte enhancer factor-2 (MEF2) family of transcription factors. Messenger RNA (mRNA) from MEF2A has been detected in blood vessels during early embryogenesis. The gene for MEF2A is located on chromoso...
Mega- (prefix): The
combining form "mega-" comes from the Greek "megas", great or big and means
abnormally large. Megalocephaly is too large a head. Megacardia is too large a
heart. Megacolon is too large a colon. ...
Megabase: Unit of length for DNA fragments that is equal to 1 million nucleotides. A megabase (Mb) is roughly equal to 1 centiMorgan (cM)....
Megacolon: An abnormally enlarged colon. ...
Megakaryocyte: A giant cell in the bone marrow that is the
ancestor of blood platelets. ...
Megalencephaly: Also called macrencephaly, a condition in which there is an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the child. Head enlargement may be evident at birth or the head may become abnormal...
Megrim: Migraine. Usually periodic attacks of headaches on one or both sides of the head. Megrim (migraine) may be accompanied by nausea, vomiting, increased sensitivity of the eyes to light (photophobia), increased sensitivity to sound (phonophobia), dizziness, blurred vision, cognitive disturbance...
Meibomian cyst: A cyst of the little glands called Meibomian glands that are located in the eyelids and make a lubricant they discharge through their tiny openings in the edges of the lids. The lubricant is a fatty substance called sebum characteristic of sebaceous glands.
The Meibomian glands are ...
Meibomian gland: One of the little glands in the eyelids that make a lubricant called sebum which they discharge through their tiny openings in the edges of the lids.
The meibomian glands can become inflamed, a condition termed meibomianitis or meibomitis, due to allergy, acne in adolescence, and r...
Meibomianitis: Inflammation of the little glands called Meibomian glands located in the eyelids that make a lubricant which they discharge through their tiny openings in the edges of the lids. The lubricant is a fatty substance called sebum characteristic of sebaceous glands. Meibomianitis may be d...
Meibomitis: See: Meibomianitis....
Meiosis: The process of germ cell formation. During meiosis, each chromosome pairs with the other chromosome in the pair and they exchange segments of genetic material. In both women and men, the autosomes (non-sex chromosomes) pair. In women, the X chromosomes pair; and in men, the X and Y chromoso...
Meiotic: Pertaining to meiosis (the process of germ cell formation). ...
Meiotic drive: Preferential selection during meiosis (germ cell production). In meiotic drive there is preferential production of certain gametes. This alters the segregation of genes from the Mendelian expectations. Meiotic drive is a mechanism for transmission distortion....