Distribution of hyaluronan in bull reproductive organs.

To study the expression of hyaluronan in male reproductive organs and the origin of seminal plasma hyaluronan, we stained various parts of the bull reproductive tract for hyaluronan using a biotinylated probe derived from cartilage proteoglycan (bHABC). The potential loss of hyaluronan during tissue processing was checked with a novel technique by blotting frozen tissue sections on nitrocellulose and staining the blots with bHABC. In the same tissues the CD44 receptor was visualized by Hermes 1 antibody. The testes showed only traces of hyaluronan, whereas both the epithelium and the connective tissue of seminal vesicle, prostate, Cowper's gland, and epididymis were positive in bHABC staining. Hyaluronan was localized on the basolateral surfaces of these epithelial cells. The secretions inside the seminal vesicle and in the ducts of prostate and Cowper's gland were HA-positive, whereas the luminal contents of seminiferous tubules and epididymis were unstained both in paraffin sections and in the in situ blocks. The data indicate that hyaluronan in seminal plasma originates from the accessory sex glands. The co-localization of CD44 with hyaluronan in the basolateral surfaces of the accessory gland epithelia and its absence from other epithelia with little or no hyaluronan supports its role as a hyaluronan receptor.