Structures of the Male Reproductive System
1.External Genitalia
•The penis contains three columns of erectile tissue and the urethra, which terminates at the glans.
•The scrotum is divided by a septum. Each scrotal sac contains a testis, epididymis, and vas deferens.
•The testes are two ovoid glands that contain seminiferous tubules, in which spermatogenesis occurs, and interstitial cells, which produce testosterone.
2.Internal Genitalia
•The epididymis extends from seminiferous tubules of each testis.
•The vas deferens extends from epididymis and entrs the ejaculatory duct in the prostate gland. This uncoiled, fibromuscular tube is surrounded by arteries, veins, and a thick, fibrous coating.
•The spermatic cord extends from the testis through the inguinal canal to the abdominal cavity. It is a bundle of blood vessels, nerves muscle fibers and the vas deferens.
•The seminal vesicles, positioned behind the bladder, are two convoluted pouches that empty into the ejaculatory ducts and are lined with secretory epithelium.
•The ejaculatory ducts join the seminal vesicles and urethra. They pass through the prostate gland and terminate in the prostatic urethra.
•The prostate gland, located under the bladder and surrounding the urethra, is a walnut-sized gland divided into five lobules by the urethra and ejaculatory ducts.
•The urethra leads from the base of the bladder through the prostate gland to the shaft and glans of the penis and is divided into three sections: the prostatic, membranous and penile urethra.
3.Bulbourethral glands, or Cowper’s glands, are two pea-sized glands located beside the prostate. They drain into the urethra.
Functions of the Male Reproductive System
1.External genitalia
•The penis serves as the male organ of copulation and the passageway for urine. Sexual excitement leads to venous congestion, which causes distension and erection.
•The scrotum protects and supports the testes and sperm.
•The testes produce mature, functional spermatozoa. This is referred to as spermatogenesis, which begins at puberty and continues throughout life. It occurs in several stages:
oSpermatogonia grow and develop into primary spermatocytes each containing 44 autosomes and 2 sex chromosomes, X and Y.
oPrimary spermatocytes divide to become secondary spematocytes, each containing 22 autosomes and 1 sex chromosome, an X or Y.
oSecondary spermatocytes divide to form spermatids, each retaining 23 chromosomes.
oSpermatids mature into spermatozoa.
2.Internal genitalia
•The epididymis stores sperm as it develops the power of motility and the capability to fertilize the female ovum.
•The vas deferens stores most sperm. During this time sperm continues to mature.
•The seminal vesicles produce yellowish, alkaline fluid rich in basic sugar and protein. This fluid enhances sperm motility by nourishing the sperm and improving pH.
•The ejaculatory duct is the passage through which semen enters the urethra.
•The prostate gland secretes fluid during sexual activity to add volume to semen, enhance sperm motility, and neutralize male urethral and vaginal acidity to enhance fertility.
•The urethra serves as passageway for semen during ejaculation and as a canal for urine during voiding.
•The bulbourethral glands secrete an alkaline fluid that also neutralizes the acid secretions found in the urethra to ensure the safe passage of sperm.
3. Testosterone, secreted by testicular interstitial cells (Leydig’s cells), is essential for the development and maintenance of male sex organs and secondary sex characteristics. Testosterone secretion begins in utero and increases at puberty. It is controlled by LH and FSH secreted by the anterior pituitary.
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