Three-dimensional analysis and in vivo imaging for sperm release and transport in the murine seminiferous tubule

Abstract

Spermatozoa released from Sertoli cells must be transported to the epididymis. However, the mechanism of the luminal flow in seminiferous tubules has remained unclear to date. Therefore, in this study, we investigated luminal flow and movements in the seminiferous tubules by three-dimensional analysis and in vivo imaging. Serial 5-μm-thick mouse testicular sections at 50-µm-intervals were prepared and stained by Periodic Acid Schiff-hematoxylin. After three-dimensional reconstruction of the seminiferous tubules, the localization of the released spermatozoa and the stages observed in the sections were recorded in each reconstructed tubule. Luminal movements in the seminiferous tubules were observed by in vivo imaging using a fluorescent-reporter mouse and two-photon excitation microscopy system. Spermatozoa without contact to the seminiferous epithelium were not accumulated toward the rete testis. Additionally, such spermatozoa were found on their way not only to the most proximal rete testis but also a more distant rete testis from any stage VIII seminiferous epithelia. In vivo imaging demonstrated that the direction of the flagella of spermatozoa attached to the seminiferous epithelium was repeatedly reversed. The epithelium at the inner curve of the seminiferous tubule was shaken more actively and had fewer spermatozoa attached compared with the epithelium at the outer curve. Our results hence suggest that the luminal flow in the seminiferous tubules is repeatedly reversed and that this physical force helps spermatozoa to be released from Sertoli cells.

Expression patterns of sex steroid receptors in developing mesonephros of the male mouse: three-dimensional analysis

“…al. 1994;Kanazawa et al 2022). Loss of ESR1 expression, as well as treatment with a potent anti-estrogen chemical, inhibits ion transport and water physiology in the efferent ducts, causing massive dilation of the ductules, as uid cannot exit quickly enough through the single common duct that enters the head of the epididymis(Hess et al.…”

A Single Administration of Progesterone during the Neonatal Period Shows No Structural Changes in Male Reproductive Tracts in Mice

“…However, the effects of P4 on male reproductive tracts have been less considered. The major function of the efferent ducts is to absorb luminal fluid from the testis, which contributes to concentrating spermatozoa and facilitating the flow of the fluid from the seminiferous tubule to the epididymal duct [2,16]. Any disturbance to this function can lead to dilation of the rete testis and efferent ducts, resulting in failure of spermatogenesis [10,22].…”

SOX17-positive rete testis epithelium is required for Sertoli valve formation and normal spermiogenesis in the male mouse

“…6d, e ). The physical force of repeatedly reversed luminal fluid flow has been reported to force spermiation in the STs 41 , while shear forces of fast fluid flow in the STs induce detachment of germ cells from the seminiferous epithelium 41 . These observations suggest that altered sheer stress caused by the disrupted fluid dynamics in the ST can be responsible for the spermiation defects observed in Sox17- cKO mice.…”