Intercellular junctional complexes of the rat seminiferous tubules: A freeze‐fracture study

Abstract

This paper provides a description of the intercellular junctions in the rat testis, as observed using the freeze fracture technique. These intercellular junctions were categorized into four general types: Sertoli cell tight junctions, myoid cell tight junctions, gap junctions, and "heterogeneous junctions." The Sertoli cell tight junctions had a mean depth of 3.1 micron in the basal to apical direction, and contained 25 to 50 (average: 36) parallel rows of particulate sealing elements. The myoid cell tight junction was neither continuous nor extensive, but focal in nature. Interestingly the sealing elements of this junction, like those of the Sertoli cell tight junction, were quite particulate in nature. Typical gap junctions were observed between Sertoli cells where they were intercalated between the parallel rows of the Sertoli cell tight junction. The most interesting observation was the identification of gap junction-like structures, in various stages of formation, on germ cell membrane fracture faces, both in the basal and adluminal compartments. Lastly, the unusual "heterogeneous junction" was observed on large membrane fracture faces in close proximity to cells in the adluminal compartment, presumably between Sertoli cells. These junctions appeared to consist of both tight and gap junction elements.

Modified expression of testicular gap-junction connexin 43 during normal spermatogenic cycle and in altered spermatogenesis

“…As compared to the classical immunofluorescence experiments, where the thickness of the section did not allow us to follow precisely the Cx43 organization, high-resolution confocal analysis of the Cx43 signal, coupled with a thin confocal planes, revealed precisely that two different signals were present at the base of the seminiferous epithelium: a continuous, ribbon-like signal of high intensity; and a few thin, immunoreactive dots, which are not, in this location, evidenced by classical immunofluorescence (Risley et al 1992;Tan et al 1996;Lablack et al 1998, present data). According to their localization and early morphological data (Gilula et al 1976;McGinley et al 1977), it can be proposed that the marked linear signal reflects Cx43 localized to SertoliSertoli gap junctions. It is presently difficult to ascertain whether the punctate immunostaining reflects Cx43 associated with gap junctions between germ cells and Sertoli cells.…”

“…By using freeze-fracture microscopy, the presence of these junctions has been reported in the testis of rat and mouse prior to and during the initiation of spermatogenesis (Gilula et al 1976;Nagano and Suzuki 1976a). In seminiferous tubules of mature animals, gap junctions are located in the region of Sertoli cell occluding junctions (Eusebi et al 1983;Russel and Peterson 1985) and between Sertoli and germinal cells (McGinley et al 1977;Zipparo et al 1982).…”

The blood‐testis barrier and sertoli cell junctions: Structural considerations

“…13a) (McGinley et al, 1979;Pelletier and Friend, 1983a), minute gap (Fig. 13b) (McGinley et al, 1977;Szollozi and Marcaillou, 19801, and variably sized adhering junctions (Figs. 13a,b) (Kaya and Harrison, 1976;Russell, 1977a) have also been shown on Sertoli cell membrane segments that face an adjoining germ cell membrane.…”

The blood–testis barrier in the toad (Bufo arenarum hensel): A freeze‐fracture and lanthanum tracer study

“…It has been established that spermatogonia and preleptotene and leptotene spermatocytes reside in the basal compartment of the epithelium beneath the Sertoli cell junctions, and that as germ cell differentiation proceeds, newly formed junctional complexes isolate zygotene spermatocytes and all germ cells in more advanced stages of maturation on the adluminal side of the blood-testis barrier (Dym and Cavicchia, 1977;Russell, 1978;Connell, 1980). Freeze -fracture techniques show that Sertoli -Sertoli junctions are characterized by parallel occluding or tight junctions, which surround the entire circumference of the cells, and in which the intramembrane-associated particles are preferently located on the E-fractured faces (Fawcett, 1975a;Gilula et al, 1976;Nagano and Suzuki, 1976a, b;McGinley et al, 1977;Meyer et al, 1977;Nagano et al, 1977Nagano et al, , 1982Connell, 1978Connell, , 1980Nagano, 1980). In the toad testis, Sertoli cell junctions with these characteristics have recently been identified in platinum replicas (Cavicchia and Moviglia, 1982).…”