The Blood-Epididymal Barrier

Abstract

The male reproductive system, especially the testis and epididymis, plays a critical role in sperm production and maturation. Spermatozoa produced in the testis are initially immobile and dysfunctional. They gain their fertilization potential and mobility during their passage through the epididymis. The epididymis, a highly segmented and convoluted canal adjacent to the testis, is surrounded by an epithelium composed of various cell types, including principal cells, clear cells, narrow cells, apical cells, basal cells, halo, and mononuclear phagocytes. The epithelial cells and the blood-epididymal barrier provide a special microenvironment for sperm maturation by selectively transporting and protecting them from harmful agents. The blood-epididymis barrier is conducted by tight junctions (TJs) between epithelial cells, regulates the paracellular transport of ions, molecules, and water, and provides polarity to the cells. In addition, epididymosomes, exosomes secreted by epididymal epithelial cells, play an essential role in sperm development by delivering critical proteins. In this chapter, the structure of the blood-epididymal barrier is presented in detail. © 2025 Nova Science Publishers, Inc. All rights reserved.