The Histology Guide

Male Reproductive system: Epidymis

diagram of testis

The genital ducts

The looped seminiferous tubules in the testes are connected to the genital duct system which transports the spermatozoa and fluid component of the semen to the outside.

This duct system is made up of the tubuli recti (short straight tubules connected to the seminiferous tubules), the rete testis - which is found in the mediastinum testis. The rete testis empties into the ductuli efferentes that lead into the ductus epididymus.

The ductus epididymus empties into the vas deferens, which empties into the ejaculatory duct, which empties into the urethra and passes to the outside.

The arrangement of these ducts is shown in the diagram.

This is an image of the epididymis.

Can you identify the specialisations on the lining epithelium? Is this a simple, stratified or pseudostratified epithelium? Can you also identify the basement membrane, and layer of smooth muscle surrounding the duct?

The epithelium also contains 'basal' cells - the nuclei are close to the basement membrane - can you identify these.

The epididymis

The ductulis efferentes and the ductus epididymus make up the epididymis. These ducts are highly coiled, and make up a single tube in the epididymis that can be up to 6 metres long. This means that several sections of it can be found on a single slide.

The ductus epidymis is a storage reservoir for spermatozoa that become matured here, and competent to fertilise ova. Fluid is absorbed here, and the epithlium is also secretory.

The epithelium is pseudostratified, with long immotile 'sterocilia' which are in fact very long microvilli. These are thought to be involved in absorption of fluid. The cells are also thought to be secretory, but the nature of the secretions is unknown.

Vas (ductus) deferens

This image shows the vas deferens (ductus deferens). It is a thick walled tube, lined with an inner (I) and outer layer of longitudinal smooth muscle (0) and a middle layer of circular muscle (C). Can you recognise these three layers of muscle?

Stimulation by the sympathetic nervous system causes the contraction of this muscle, to expel its contents into the urethra during ejaculation. The duct is lined by a pseudostratified epithelium, and the supporting lamina propria is folded, which means it is able to expand during ejaculation.

The distal portion of ductus deferens (the ampula) receives a duct draining from the seminal vesicle - forming the short ejaculatory duct. These ducts converge to join the urethra, as they pass through the prostate gland.

photo of ductus

This image shows the epithelial lining of the vas deferens. Can you identify the pseudostratified tall columnar cells?

It is similar to that of the seminal vesicles.