Effects of Testosterone
Testosterone (tes′tos′t̆e-r̄on) is the major male hormone secretedby the testes. Testosterone influences reproductive organs and nonreproductive structures (table 19.2). During puberty, testoster-one causes the enlargement and differentiation of the male genitals and the reproductive duct system. It is necessary for spermatogen-esis and for the development of male secondary sexual character-istics. The secondary sexual characteristics are those structural and behavioral changes, other than in the reproductive organs, that develop at puberty and distinguish males from females.
Secondary sexual characteristics in males include hair distribution and growth, skin texture, fat distribution, skeletal muscle growth, and changes in the larynx. After puberty, testosterone maintains the adult structure of the male genitals, reproductive ducts, and secondary sexual characteristics.