The normal development of the blood‐testis barrier and the effects of clomiphene and estrogen treatment

Abstract

Previous work with electron opaque intercellular markers has indicated that in adults occluding junctions between adjacent Sertoli cells are the principal morphological basis of the blood‐testis barrier (Dym and Fawcett, '70). Since the barrier of not present at birth this study was undertaken to determine when it is established during postnatal development of the rat and to correlate its appearance with other developmental events in the seminiferous epithelium. From birth to 16 days of age interstitially injected tracers, such as horseradish peroxidase, freely entered the seminiferous epithelium and permeated the 200 Å intercellular clefts between presumptive Sertoli cells and germ cells, reaching the center of the seminiferous cords and site of the future tubule lumen. Between day 16 and 19 occluding junctions between Sertoli cells appear and thenceforth interstitially injected electron opaque tracers were effectively prevented from reaching the tubule lumen. Therefore, in rats, the blood‐testis barrier is established between 16 and 19 days of age. In an attempt to determine whether the development of the Sertoli cell junctions and the blood‐testis barrier is under hormonal control circulating gonadotropins were suppressed using daily injections of clomiphene or estrogens from birth. The appearance of blood‐testis barrier was delayed approximately seven days in the absence of gonadotropins. However, by day 26 the Sertoli cell junctions did appear and interstitially injected tracers were prevented from reaching the tubule lumen. Thus the development of the occluding junctions between Sertoli cells that constitute the permeability barrier does not appear to be directly dependent upon gonadotropins.