EXTRAVASCULAR AND INTRATUBULAR DIFFUSION OF LABELED SERUM PROTEINS IN THE RAT TESTIS

Abstract

Rat whole serum, albumin, globulins, and fibrinogen were labeled with fluorescent dyes (sulforhodamine B. CI No. 45100 and fluorescein isothiocyanate); albumin was also tagged with radioactive iodine (I¹³¹) and tritium (H³). In addition heterologous albumin was also labeled with fluorescent dyes and radioiodine. The proteins were intravenously injected in prepubertal, pubertal and adult rats, and their decay in the circulation and histological distribution in the testis and epididymis was studied. As controls other animals were similarly injected with free labels alone and with labeled denatured and degraded albumin; also unlabeled homologous and heterologus albumins were administered followed by incubation of both organs with the corresponding labeled antisera applying the Coons' technique. It was observed: 1) with the exception of fibrinogen, labeled serum proteins rapidly appeared in the lumina of vessels, diffused extravascularly in the intertubular spaces and finally arrived inbetween the germinal cells and in the lumina of seminiferous tubules. Also labeled material was present in the lumen of epididymal canaliculi but not in the ductus deferens. 2) This extravascular and intratubular diffusion was parallel to the fast component of the time decline curve of labeled homologous serum proteins in the circulation. 3) There was no great difference between young and adult rats in the extravascular diffusion process, but intratubular passage was higher in pubertal and adult animals. 4) Control experiments revealed time presence of some fluorescent material only in the vessels and macrophages, whereas the immunofluorescent technique showed to very similar localization of unlabeled proteins to that provided by the injection of directly labeled proteins.