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Reproductive System Male Reproductive System Formation of Sperm Cells • Spermatogenesis – sperm production. 4 sperm cells result from meiosis of a primary spermatocyte. • Spermiogenesis – process of sperm cell maturation. • Sperm cell parts: – Head • Contains the nucleus with 23 chromosomes – Midpiece – tail Organs of the Male Reproductive System • Testes – Must descend (inguinal canal) in order to lower temperature for sperm production – Undescended testes cannot produce sperm cells *testes produce sperm cells and male sex hormones. Structure of Testes • Lobules separated by connective tissue • Filled with seminiferous tubules • Seminiferous tubules contain undifferentiated cells that give rise to sperm cells • Interstitial cells produce male sex hormones and are located between the seminiferous tubules. Male Internal Accessory Organs • • • • • • Epididymus – Located on the outside of the testis and leads to the ductus deferentia Ductus deferentia – Muscular tube – Forms part of the spermatic cord Seminal vesicles – Saclike structure attached to the ductus deferens • Secretes alkaline fluid that contains nutrients such as fructose that is added to sperm cells entering the ejaculatory duct. Prostate gland – Surrounds the urethra just below the urinary bladder – Secretes thin, milky fluid which enhances sperm mobility and neutralizes the fluid containing the sperm cells and acidic secretions of the vagina. Bulbourethral glands – Two small structures inferior to the prostate gland that secrete a fluid that lubricates the penis in preparation for sexual intercourse Semen – Sperm cells and secretions of seminal vesicles, prostate gland, and bulbourethral glands. – Sperm cells in semen swim, but cannot fertilize the egg cell until they enter the female reproductive tract. External Reproductive Organs • Scrotum – Pouch of skin and subcutaneous tissue that encloses the testes. • Penis – Conveys urine and semen – Becomes erect for insertion into the vagina during sexual intercourse – Body is composed of 3 columns of erectile tissue surrounded by connective tissue – Root of the penis is attached to the pelvic arch and membranes of the perineum.
