Histology Study Guide
Male Reproductive System
INTRODUCTION TO THE MALE REPRODUCTIVE TRACT
The male tract begins with the testis, leads through the windings of the epididymis, then through the vas deferens, past a gland called the seminal vesicle, through the prostate by way of the ejaculatory duct, into the prostatic urethra, and finally through the penis in the penile urethra.
The testis is a gland-like structure consisting of many seminiferous tubules embedded in relatively sparse interstitial tissue.
- The tubules are lined by a simple columnar epithelium of Sertoli cells.
- Interspersed within the tubular epithelium are germ cells. Meiotic cell divisions lead from spermatogonia through primary and secondary spermatocytes to cells called spermatids, which mature into spermatozoa.
- Interstitial tissue between the tubules contains clusters of endocrine Leydig cells which secrete testosterone.
- All of the seminiferous tubules converge onto a network of interconnecting tubules, the rete testis, which in turn lead through numerous small efferent ductules into the larger duct which extends through the epididymis.
The initial portion of the duct which conducts sperm from the testis to the urethra is contained within the epididymis.
- The epididymal duct is extremely long (4 to 5 meters) but is highly convoluted to fit within a small space along the testis.
- The epididymal duct is lined by a two-layered columnar epithelium and surrounded by smooth muscle.
- Sperm maturation occurs during passage through the epididymis.
The vas deferens is the relatively straight, muscular portion of the duct which carries sperm cells from the epididymis to the ejaculatory duct.
- Like the epididymal duct, the vas deferens is lined by a two-layered columnar epithelium.
- The vas deferens has a thick, three-layered muscular wall.
- The vas deferens ends at its confluence with the duct of the seminal vesicle.
The seminal vesicle is a gland which contributes most of the volume to the seminal fluid, including nutrients (notably fructose) for the sperm cells.
The ejaculatory duct passes through the prostate, beginning at the the confluence of the vas deferens with the duct of the seminal vesicle and continuing to the prostatic urethra.
The prostate is a complex of tubular glands embedded in a thick fibromuscular stroma.
- The prostate surrounds the urethra just below the bladder. Its secretions contribute enzymes (and prostaglandins) to seminal fluid.
- Because of its location, its "normal" propensity toward enlargement, and the frequency of prostate cancer, the prostate is an organ with special clinical significance. For an accessible introduction, see the WebPath tutorial on the prostate.
The penis contains erectile tissue, a specialized arrangement of arteries, shunts, and vascular sinusoids which permit erection.
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Last updated: 12 January 2005 / dgk