Cavicchia J C, Moviglia G A
Anat Rec. 1983 Apr;205(4):387-96. doi: 10.1002/ar.1092050404.
Intercellular junctions between Sertoli cells in the toad testis were studied by freeze-fracture and electron-opaque intercellular markers. These junctional specializations are characterized in thin sections by a series of focal fusions on the outer leaflets of both adjacent cell plasmalemmas, associated with bundles of fine filaments in the subjacent Sertoli cell cytoplasms. However, the wide subsurface cisterna of the endoplasmic reticulum, a component constantly associated with Sertoli cell junctions in mammals, is absent in the toad. The intravascularly injected lanthanum hydroxide, used as a tracer compound, gains access to the seminiferous tubules and surrounds spermatogonia and leptotene spermatocytes, but is persistently excluded from germ cells in later stages of development. This indicates that, as is the case in the mammalian testis, a permeability barrier to lanthanum is established which isolates all germ cells beyond leptotene spermatocytes. Freeze-fracture reveals the characteristic occluding junctions between Sertoli cells, but a variation in their geometric patterns was clearly observed in different regions of the toad seminiferous epithelium. The membrane-fractured faces of Sertoli cells embracing differentiating spermatids exhibit a deep junctional complex: up to 50 rows of particles between adjacent Sertoli cells separate these late germ cells from the periphery of the seminiferous tubules. Sertoli cells surrounding early germ cells generally exhibit, instead, a discontinuous, poorly developed network of interconnected rows of particles with few widely spaced strands. This seems to permit the percolation of the intercellular marker in areas of the seminiferous epithelium containing spermatogonia and leptotene spermatocytes.
通过冷冻断裂和电子不透明细胞间标记物研究了蟾蜍睾丸支持细胞间的细胞连接。这些连接特化在薄切片中的特征是相邻细胞质膜外小叶上的一系列局灶性融合，与下方支持细胞细胞质中的细丝束相关。然而，蟾蜍中不存在内质网的宽表面下池，而在内哺乳动物中，该结构是与支持细胞连接始终相关的成分。血管内注射用作示踪剂的氢氧化镧可进入生精小管并包围精原细胞和细线期精母细胞，但在发育后期的生殖细胞中始终被排除在外。这表明，与哺乳动物睾丸一样，建立了对镧的通透性屏障，将细线期精母细胞之后的所有生殖细胞隔离开来。冷冻断裂揭示了支持细胞间典型的封闭连接，但在蟾蜍生精上皮的不同区域明显观察到其几何模式存在差异。包围分化中精子细胞的支持细胞膜断裂面呈现出深的连接复合体：相邻支持细胞之间多达50排颗粒将这些晚期生殖细胞与生精小管外周分隔开。相反，包围早期生殖细胞的支持细胞通常呈现出不连续、发育不良的相互连接颗粒行网络，只有少数宽间距的链。这似乎允许细胞间标记物在含有精原细胞和细线期精母细胞的生精上皮区域中渗透。
