Blood-Testis Barrier and Sperm Delayed in the Cauda Epididymis of the Reproductively Regressed Syrian Hamsters

Abstract

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.

Keywords: Blood-testis barrier; Male Syrian hamster; Photoperiod; Reproductive activity.

Fig. 1.. Changes of actual weights of testes, epididymides, and seminal vesicles in Syrian hamster at the end of experiment.

Note that SP animals showed completely regressed testes, epididymides, and seminal vesicles. * indicates statistical significance (p<0.05). LP, long photoperiod; SP, short photoperiod (n=6).

Fig. 2.. Changes of testicular mass of Syrian hamster.

The testicular masses of Syrian hamsters were gauged at 4 weeks intervals. * indicates statistical significance (p<0.05). LP, long photoperiod; SP, short photoperiod.

Fig. 3.. Changes of testicular mass in individual animals.

LP, long photoperiod; SP, short photoperiod.

Fig. 4.. Representative RT-PCR results of claudin-11, occludin, and JAM genes.

RT-PCRs were performed in testes of Syrian hamsters housed in each photoperiod. LP, long photoperiod; SP, short photoperiod; M, 100 bp marker; Cldn, claudin-11; Occl, occludin; JAM, junction adhesion molecule; GAPDH, glyceraldehydes-3-phosphate dehydrogenase.

Fig. 5.. Representative histological view of testis.

The rectangles in upper row are amplified in lower row. Bar in upper row=100 µm. Bar in lower row=50 µm. LP, long photoperiod; SP, short photoperiod.

Fig. 6.. Representative histological view of epididymis.

A demonstrates the cauda epididymis. B presents the proximal part of cauda epididymis and C the distal part of cauda epididymis. The upper and lower rectangles in A are enlarged in B and C, respectively. The rectangles of the top row in B and C are amplified in lower row. Scale bar in A=2 mm. Scale bar in top picture of B and C=1,000 µm. Scale bar in middle picture of B and C=500 µm. Scale bar in lower picture of B and C=125 µm. LP, long photoperiod; SP, short photoperiod.