The scrotum holds the testes outside the abdominal cavity and maintains them about 2–2.5°C below normal internal body temperature. This lower temperature is necessary for spermatogenesis. Within each testis, testicular lobules contain the seminiferous tubules where sperm formation occurs.
Where are spermatogonia, Sertoli cells and Leydig cells found, and what does each contribute?
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Spermatogonia are male germ cells in the lining of seminiferous tubules and give rise to the sperm-forming lineage. Sertoli cells in the tubules nourish developing germ cells. Leydig cells lie in the interstitial spaces between tubules and secrete androgens.
Starting in the seminiferous tubules, trace sperm through the rete testis, vasa efferentia, epididymis and vas deferens. The vas deferens joins the seminal-vesicle duct to form the ejaculatory duct, which opens into the urethra. The urethra carries sperm to the external urethral opening; sperm do not travel through the ureters or urinary bladder.
What forms seminal plasma, what substances is it rich in, and what additional role do bulbourethral secretions have?
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Secretions of the paired seminal vesicles, prostate and paired bulbourethral glands form seminal plasma. It is rich in fructose, calcium and certain enzymes. Bulbourethral secretions also provide lubrication.