marijuana A common street and recreational drug that comes from the marijuana plant: the hemp plant cannabis sativa. The pharmacologically active ingredient in marijuana is tetra-hydro-cannabinol (THC). Marijuana is used to heighten perception, affect mood, and relax. Many people think marijuana is harmless, but it is not. Signs of marijuana use include red eyes, lethargy,…
mark, strawberry See hemangioma, capillary.
marker 1 See gene marker. 2 A blood marker or a tumor marker. See also blood marker; tumor marker.
Maroteaux-Lamy syndrome A form of mucopolysaccharidosis with onset before age 3 that is characterized by an inability to metabolize dermatan sulfate. This leads to abnormal accumulation of dermatan sulfate, mostly in the peripheral tissues. The result is mild to severe changes in muscle, bone, skin, and other tissues, particularly the heart. Diagnosis is made through…
marriage, cousin See consanguinity.
marsh fever See malaria.
Martin-Bell syndrome See fragile X syndrome.
MASA syndrome A syndrome named for its characteristics: mental retardation, aphasia, shuffling gait, and adducted thumbs. Features of the syndrome include mental retardation and aphasia (lack of speech); adducted (clasped) thumbs, absent extensor pollicis longus and/or brevis muscles to the thumb, shuffling gait, and leg spasticity; small body size; and lumbar lordosis (swayback). MASA is…
male external genitalia The external genital structures of the male, comprising the penis, the male urethra, and the scrotum.
male gonad A testis, one of a pair of organs located behind the penis in a pouch of skin called the scrotum. The testes produce and store sperm and are also the body’s main source of male hormones. These hormones control the development of the reproductive organs and other male characteristics, such as body and…
male internal genitalia The internal genital structures of the male that are concerned with reproduction, including the testis, epididymis, ductus deferens, seminal vesicle, ejaculatory duct, bulbourethral gland, and prostate.
male organs of reproduction The sum total of all the genital organs—internal and external—of the male that are concerned with reproduction. See also male external genitalia; male internal genitalia.