testosteronesecreting

Testosteronesecreting describes cells or tissues that synthesize and release testosterone, a steroid hormone in the androgen family. In humans, the principal source is the Leydig cells of the testes, which produce most circulating testosterone after puberty. Additional androgen production arises from ovarian theca cells in females and, to a lesser extent, the adrenal cortex.

Testosterone biosynthesis begins with cholesterol, converted to pregnenolone by mitochondrial cytochrome P450scc (CYP11A1). Through a series of enzymatic steps involving enzymes such as 3β-HSD and 17β-HSD, pregnenolone is transformed into testosterone. Luteinizing hormone (LH) from the pituitary stimulates Leydig cells to increase production, while follicle-stimulating hormone (FSH) supports spermatogenesis via Sertoli cells. Testosterone exerts negative feedback on the hypothalamic-pituitary axis, regulating its own production.

Physiologically, testosterone supports the development of male reproductive organs, the emergence of male secondary sexual characteristics, and normal sperm production. It also influences bone density, muscle mass, fat distribution, and libido. In females, androgens contribute to ovarian function and roughly balance estrogen effects.

Clinical relevance centers on abnormal testosterone secretion. Excess secretion by tumors or hyperplasia can cause virilization and signs of hyperandrogenism; insufficient production can lead to hypogonadism and reduced secondary sexual characteristics. Diagnosis typically involves measuring serum testosterone levels, sometimes by mass spectrometry, and imaging to locate sources such as testicular, ovarian, or adrenal lesions.