Webster's New World Medical Dictionary

mini-stroke
See 
transient ischemic attack.
minor
In general, something that is less than
something else. For example, the teres minor mus-
cle is smaller than the teres major muscle.
minor salivary gland
A small gland that pro-
duces saliva. The mouth and palate contain numer-
ous 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 miscar-
riage 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 in the mother that
make it difficult for her to carry a fetus to term, such
as antiphospholipid syndrome.
missense mutation
A genetic change that
results in the substitution of one amino acid in pro-
tein 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.
mitochondria
Structures located in the cell’s
cytoplasm outside the nucleus. Mitochondria are
responsible for energy production. Each consists of
two sets of membranes: a smooth, continuous outer
coat and an inner membrane arranged in tubules or
in folds that form plate-like double membranes
(cristae). The mitochrondria are the principal
energy source of the cell. They not only convert
nutrients into energy but also perform many other
specialized tasks. Each mitochondrion has a chro-
mosome that is made of DNA but is otherwise quite
different from the better-known chromosomes in
the nucleus. The mitochondrial chromosome is
much smaller than other chromosomes. It is round,
whereas the chromosomes in the nucleus are
shaped like rods. There are many copies of the
mitochondrial chromosome in every cell, whereas
there is normally only one set of chromosomes in
the nucleus. All mitochondrial chromosomes are
inherited from the mother.