Dictionary

minor In general, something that is less than something else. For example, the teres minor muscle is smaller than the teres major muscle.

minor salivary gland A small gland that produces saliva. The mouth and palate contain numerous minor salivary glands.

minoxidil A medication (brand names: Loniten, Rogaine) that was originally developed to treat high blood pressure as an oral medication and is now also used in topical form to promote hair growth.

miosis Contraction of the pupil. The opposite of miosis is mydriasis.

miscarriage Inadvertent loss of a pregnancy before the fetus is viable. A considerable proportion of pregnancies end in miscarriage. Also known as spontaneous abortion.

miscarriages, multiple More than one miscarriage for a woman. In multiple miscarriages, there is about a 5 percent chance that one member of the couple is carrying a chromosome translocation that is responsible for the miscarriages. Other causes of multiple miscarriage include Rh incompatibility, exposure to toxic substances that harmed the embryo, and physical problems…

missense mutation A genetic change that results in the substitution of one amino acid in protein for another. A missense mutation is responsible for sickle hemoglobin, the molecular basis of sickle cell trait and sickle cell anemia.

mite-borne typhus See typhus, scrub.

micropenis An abnormally small penis. In medical practice, the dimension of the penis that is measured is the length. The measurement is taken along the upper surface of the shaft of the penis to the tip, using a measuring tape or, preferably, a ruler. The ruler is pressed firmly into the soft tissue over the…

microphallus See micropenis.

microphthalmia An abnormally small eye. Microphthalmia is a congenital malformation of the globe, a birth defect of the eye. A related term, anophthalmia, indicates that there is no eye at all. Also known as microphthalmos.

microscope An optical instrument that augments the power of the eye to see small objects. Most optical microscopes today are compound microscopes.