The testes contain two main parts: the seminiferous tubules and Leydig cells. The seminiferous tubules contain Sertoli cells that nurture developing sperm cells, as well as various germ cells that mature into sperm. Located between the tubules are Leydig cells, which secrete the hormone testosterone. Testosterone promotes muscle and bone growth during puberty and is essential for sperm production in adult males.

1. MALE REPRODUCTIVE GLAND By J9

2. TESTES Located in the scrotum Secrete hormone known as androgen; most important of which is testosterone Have an exocrine part, Seminiferous tubules (tightly coiled) and endocrine part, intersitial or Leydig cells (clusters)

3. Leydig cells Synthesise and secrete testosterone Located in the interstitial tissue between the convulutedseminiferous tubules Occurs in clusters, which are variable in size and richly supplied by capillaries Its cytoplasm is strongly acidophilic and finely granular The nucleus is large, round and often located eccentric in the cell

4. General effects of the testosterone Anabolic Growth of muscle mass and strength Increased bone density and strength Linear growth Bone maturation

5. Androgenic (Virilizing) Maturation of sex organs (part. Penis) Formation of scrotum in the fetus Deepening of voice (sec. sex charac.) Growth of beard and axillary hair (sec. sex charac.)

6. ...cont. testosterone Testosterone increases sharply at puberty Essential for the production of sperm Production of testosterone is controlled by the release of luteinizing hormone (LH)

8. Sertoli cells ‘nurse’ cell of the testes Part of the seminiferous tubule Activated by follicle-stimulating hormone and has FSH-receptor on its membranes. Estradiol and Inhibin – hormone secreted

9. Estradiol Prevent apoptosis (death of cells) of germ cells Inhibin Inhibit production of FSH

10. Arrows shows the location of the leydig cells

11. TESTIS 1 Lumen of Tubulusseminiferuscontortus2 spermatids3 spermatocytes4 spermatogonia5 Sertoli cell6 Myofibroblasts7 Leydig cells8 capillaries