[Cell junctions between Sertoli cells and the blood-testis barrier in goldfish testis].

Freeze-fracture and etching technique combined with thin sectioning and lanthanum impregnation has been used for the study of Sertoli cell junctions and the blood-testis barrier formation in goldfish testis with lobular organization. Some observations and results are first given in this paper. The results of experiments can be summarized as the following: 1). Sertoli cell junctions are compound junctions of tight junctions, desmosomes and gap junctions. Tight junctions usually appear as parallel or network like ridges on the P face and fine grooves on the E face at the freeze-etching replicas. Desmosomes and gap junctions often are located between or nearby the ridges of tight junctions. In addition, endoplasmic reticulum cristae near the junction area can also be observed. 2). The number, area and density of each individual junction vary with the development and differentiation stages of germinal cells in the cyst. 3). Tight junctions can be observed at any stage during germinal cell differentiation through the period of spermatogenesis and spermiogenesis. However, they appear morphologically different as type I and type II. 4). Lanthanum can partially penetrate into the intercellular spaces of spermatogonium and early primary spermatocyte but can't penetrate after the stage of late primary spermatocyte. 5). The blood-testis barrier formation starts at the stage of pachytene spermatocytes. The formation of the blood-testis barrier is the result of the development of the tight junction from type I to type II.