The pair of seminal vesicles secrete up to 85% of the total volume of seminal fluid. The lumen of each vesicle is highly irregular, giving a honeycomb appearance at low magnification, as shown here. There is a prominent layer of muscle, arranged into inner circular and outer longitudinal. Can you identify it?

During ejaculation, sympathetic stimulation causes contraction of the muscle, to force secretions into the urethra.

Can you identify the epithelium of the seminal vesicles in this magnified image of a seminal vesicle? It is a pseudostratified tall columnar type. It contains secretory cells with lipid droplets in the cytoplasm.

The fluid produced is yellow, viscid and alkaline, and contains fructose, fibrinogen, vitamin C and prostaglandins.

Examine this low power image of the prostate gland. The gland is separated into lobules by fibrous septae - can you identify a septa and the glands? This section is taken from the peripheral zone of the prostate.

The glands are branched, and the epithelium is folded. The secretory product , which makes up part of the seminal fluid, is thin and milky, rich in citric acid, and hydrolytic enzymes, including fibrinolysin, which liquefies coagulated semen after deposition in the female genital tract. The stroma lying between the secretory units is fibromuscular, and contracts to expel the secretions, during ejaculation.

This image shows the epithelium of the glands. Can you identify it, and try to classify it for yourselves?

It is a double layer of tall columnar secretory cells with basal nuclei, and a layer of flatted basal cells lying on the basement membrane. These cells produce a type of keratin not found in the secretory cells. The lamina propria is fibro-elastic.