Immunohistochemical study of serum albumin in normal and cadmium-treated mouse testis organs by "in vivo cryotechnique".

The in vivo injection of cadmium (Cd) was reported to induce blood-testis barrier disruption, and assumed to be an experimental model to examine junctional structures in seminiferous tubules. The purpose of this study is to investigate time-dependent changes of albumin permeability in the normal or Cd-treated mouse testis by our "in vivo cryotechnique" with immunohistochemistry, reflecting tight junctional (TJ) barriers of Sertoli cells. The albumin in the seminiferous tubules was firstly immobilized by the cryotechnique, in which normal blood circulation was always kept. The cryofixed testicular tissues were then processed for freeze-substitution, and embedded in the paraffin wax. Serial sections were immunostained by anti-mouse albumin antibody with peroxidase immunostaining, and also stained with hematoxylin-eosine (HE) for morphological observation. In normal seminiferous tubules, the immunoreaction products were localized around peritubular myoid cells and between Leydig cells, as well as in blood vessels. They were also localized as arch-like patterns around some spermatogonia in basal compartments of seminiferous tubules. Twenty-four and 48 hrs after Cd-treatment, some enlarged spaces and vesicular formations in the seminiferous epithelium were observed on the HE-stained sections. The albumin immunolocalization was detected not only in the basal compartments, but also in the adluminal compartments between Sertoli cells and germ cells. Thus, the structural disruptions of inter-Sertoli TJ barriers could be clearly demonstrated by the "in vivo cryotechnique".