Summary
As luminal fluid moves from the seminiferous tubule and enters the rete testis, its protein concentration declines from approximately 6 mg/ml to 1 mg/ml. It was therefore suggested that protein is either 1) utilized by the spermatozoa, 2) transported across the epithelium of the terminal segment of the seminiferous tubule, the tubuli recti or rete testis, or 3) absorbed and degraded by the epithelium. Horseradish peroxidase (HRP), a protein marker, was microperfused into single seminiferous tubules or perfused directly into the rete. After fixation, the HRP was localized histochemically and the tissue observed under the light- and electron microscope. HRP was taken up via pinocytotic vesicles into the cytoplasm of the Sertoli cells and germ cells but did not permeate extracellularly beyond the tight junctions. Similar results were obtained in the cells lining the terminal segment and the tubuli recti. The rete epithelium showed uptake of HRP into coated and noncoated vesicles, while some cells additionally revealed diffuse cytoplasmic distribution of HRP. The terminal segment, tubuli recti, and rete testis may be important routes by which proteins may leave the testicular fluid either to be degraded or to enter the blood.
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We wish to thank Joan Howe for valuable technical assistance. Part of this study was performed with Dr. B.P. Setchell at the Institute of Animal Physiology, Babraham, Cambridge, U.K. Supported by grants HD14445 and RCDA (DAK) HD00243 from the N.I.H. and AM22125 from the Diabetes Research Training Center
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Hinton, B.T., Keefer, D.A. Evidence for protein absorption from the lumen of the seminiferous tubule and rete of the rat testis. Cell Tissue Res. 230, 367–375 (1983). https://doi.org/10.1007/BF00213810
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DOI: https://doi.org/10.1007/BF00213810