• Journal of Animal Reproduction and Biotechnology
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• v.34 no.3
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• pp.190-196
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• 2019

Tight junctions are constituents of the blood-epididymis barrier that play roles in regulating the unidirectional transcellular transport of ions, water, and solutes to maintain optimal conditions for sperm maturation and storage. Claudin 1 (Cldn1) and 4 (Cldn4) are known as tight junction proteins and are expressed in the basolateral membranes as well as tight junctions in the epididymis of rodents. Here, we examined the expression and localization of Cldn1 and 4 to determine the function of these proteins in the pig epididymis. Cldn1 was highly expressed in the basolateral membrane of epithelial cells in the caput and corpus regions of the epididymis. In the cauda region, however, Cldn1 labeling was significantly decreased in the basolateral membrane of epithelial cells. In contrast, labeling indicated that Cldn4 was expressed in the basolateral membrane in the cauda region of the epididymis and was present at punctate reactive sites in the caput and corpus regions. However, in no region of the epididymis did we detect colocalization of Cldn1 and 4 with labeled ZO-1, the distribution of which is restricted to the tight junctions. Our results indicate that Cldn1 and 4 were region-specifically expressed in the pig epididymis but not present in the tight junctions of epididymal epithelium. In addition, reciprocal regulation in specific regions of the epididymis between Cldn1 and 4 may play an important role in generating an optimal luminal environment for sperm maturation and storage in the pig epididymis.

• Journal of Animal Science and Technology
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• v.64 no.3
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• pp.500-514
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• 2022

The blood-epididymis barrier (BEB) forms a unique microenvironment that is crucial for the maturation, protection, transport, and storage of spermatozoa in the epididymis. To characterize the function of tight junctions (TJs), which are constitutive components of the BEB, we determined the expression and localization of TJ proteins such as zonula occludens (ZO)-1, 2, and 3, occludin, and claudin3 (Cldn3) during postnatal development in the goat epididymis. To assess the expression patterns of TJ proteins in immature (3 months of age) and mature (14 months of age) goat epididymides, two different experimental methods were used including immunofluorescence labeling and western blotting. We show that, ZO-1, 2, and 3, and occludin, were strictly expressed and localized to the TJs of the goat epididymis, whereas Cldn3 was present in basolateral membranes as well as TJs. All TJ proteins examined were more highly expressed in the immature epididymis compared to levels in mature tissue. In conclusion, our study indicates that at least five TJ proteins, namely ZO-1, ZO-2, ZO-3, occludin, and Cldn3, are present in TJs, and the expression strength and pattern of TJ proteins tend to be age dependent in the goat epididymis. Together, these data suggest that the distinct expression patterns of TJ proteins are essential for regulating components of the luminal contents in the epididymal epithelium and for forming adequate luminal conditions that are necessary for the maturation, protection, transport, and storage of spermatozoa in the goat epididymis.

• Development and Reproduction
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• v.25 no.1
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• pp.1-14
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• 2021

The Syrian (golden) hamsters are seasonal breeders whose reproductive functions are active in summer and inactive in winter. In experimental facility mimicking winter climate, short photoperiod (SP) induces gonadal regression. The blood-testis barrier (BTB) of the sexually involuted animals have been reported to be permeable, allowing developing germ cells to be engulfed or sloughed off the epithelium of the seminiferous tubules. The expressions of genes related to the tight junction composing of BTB were investigated in the reproductive active and inactive testes. Claudin-11, occludin, and junctional adhesion molecule (JAM) were definitely expressed in the active testes but not discernably detected in the inactive testes. And spermatozoa (sperm) were observed in the whole lengths of epididymides in the active testes. They were witnessed in only cauda region of the epididymides but not in caput and corpus regions in animals with the inactive testes. The results imply that the disorganization of BTB is associated with the testicular regression. The developing germ cells are swallowed into the Sertoli cells or travel into the lumen, as supported by the presence of the sperm delayed in the last region of the epididymis. These outcomes suggest that both apoptosis and desquamation are the processes that eliminate the germ cells during the regressing stage in the Syrian hamsters.