TRANSITIONAL CELLS AT THE JUNCTION OF SEMINIFEROUS TUBULES WITH THE RETE TESTIS OF THE RAT - THEIR FINE-STRUCTURE, ENDOCYTIC ACTIVITY, AND BASEMENT-MEMBRANE
TRANSITIONAL CELLS AT THE JUNCTION OF SEMINIFEROUS TUBULES WITH THE RETE TESTIS OF THE RAT - THEIR FINE-STRUCTURE, ENDOCYTIC ACTIVITY, AND BASEMENT-MEMBRANE
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DOI：
10.1002/aja.1001810202
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发表时间：
1988-02-01
影响因子：
--
通讯作者：
DWORKIN, J
中科院分区：
文献类型：
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作者：
HERMO, L;DWORKIN, J
移行细胞排列在位于睾丸网和生精上皮之间的大鼠生精小管的中间区域。这些高大的细长细胞沿下游方向定向，并在睾丸网腔的远端彼此会聚，形成一种独特的乳头状结构，通过该结构可以看到狭窄的未通管腔。除了广泛分布的高尔基体和线粒体外，这些细胞还含有丰富的微管、内质网池和明显的分叶状核，显示染色质团块和突出的核仁。通过使用吸附剂（阳离子铁蛋白、伴刀豆球蛋白A铁蛋白）和液相示踪剂（天然铁蛋白、辣根过氧化物酶-胶体金复合物和存在α甲基-D-甘露糖苷的伴刀豆球蛋白A铁蛋白）来检查这些细胞的内吞活性。将这些示踪剂分别注射到睾丸网腔内，并在注射后2、5、15和30分钟以及1、2和6小时处死动物。 2 分钟后，在这些细胞的顶端质膜的涂层和未涂层凹坑以及大的、次表面的、未涂层的球形、C 形和管状膜元件中发现了吸附性和液相示踪剂。 5 分钟时，在不同大小的内体中观察到示踪剂；而在15分钟和30分钟时，分别标记了小尺寸和大尺寸的苍白和致密的多泡体。在 1 小时和更长的时间间隔，次级溶酶体被标记。虽然液相和吸附示踪剂都遵循相同的途径和命运，但仅用吸附示踪剂观察到与过渡细胞的顶端和侧质膜以及界定涂覆和未涂覆凹坑的膜的结合。这些结果表明，移行细胞积极参与液相和吸附性内吞作用，这可能在改变管腔液体的组成方面发挥重要作用。中间区域远端区域的移行细胞依赖于复杂的基底膜 (BM) 复合体，该复合体包括紧邻这些细胞下方的薄 BM、厚的远端 BM 层以及以松散吻合网络形式跨越两者之间距离的 BM 股。使用针对硫酸乙酰肝素蛋白多糖、层粘连蛋白和 IV 型胶原的抗血清显示 BM 复合体的所有区域中都存在所有三种成分。在吻合BM网络的网格中，观察到细胞外囊泡。在移行细胞的基底区域以及它们的基底足状突起中也发现了类似大小和外观的囊泡，这些突起深入到吻合网络的网状结构中。虽然这种细胞外囊泡可能源自移行细胞，以及它们的基足状突起，该突起深入到吻合网络的网状结构中。虽然这种细胞外囊泡可能源自移行细胞，但其功能意义尚不清楚。
Transitional cells line the intermediate region of rat seminiferous tubules situated between the rete testis and the seminiferous epithelium proper. These tall elongated cells orient themselves in a down-stream direction and converge on one another distally in the lumen of the rete testis where they form a distinct papillalike structure through which a narrow patent lumen is apparent. In addition to widely dispersed Golgi apparatus and mitochondria, these cells contain an abundance of microtubules, cisternae of endoplasmic reticulum, and a distinct lobulated nucleus showing clumps of chromatin and a prominent nucleolus. The endocytic activity of these cells was examined by employing adsorptive (cationic ferritin, concanavalin A ferritin) and fluid-phase tracers (native ferritin, horse-radish peroxidase-colloidal gold complex, and concanavalin A ferritin in presence of .alpha. methyl-D-mannoside). Such tracers were injected separately into the lumen of the rete testis, and the animals were killed at 2, 5, 15, and 30 min and 1, 2, and 6 hr after injection. At 2 min, both adsorptive and fluid-phase tracers were found within coated and uncoated pits of the apical plasma membrane of these cells as well as in large, subsurface, uncoated spherical, C-shaped, and tubular membranous elements. At 5 min the tracers were seen in endosomes of different sizes; while at 15 min and 30 min, pale and dense multivesicular bodies of small and large sizes, respectively, were labeled. At 1-hr and longer time intervals secondary lysosomes became labeled. While both fluid-phase and adsorptive tracers followed the same pathway and fate, binding to the apical and lateral plasma membranes of the transitional cells and to the membrane delimiting coated and uncoated pits was observed only with the adsorptive tracers. These results demonstrate that the transitional cells are actively involved in both fluid-phase and adsorptive endocytosis, which may play on important role in modifying the composition of the luminal fluid. The transitional cells of the distal zone of the intermediate region rest on an elaborate basement membrane (BM) complex which includes a thin BM immediately underlying these cells, a thick distal layer of BM, and strands of BM spanning the distance between the two in the form of a loose anastomotic network. Use of antisera against heparan sulfate proteoglycan, laminin, and type IV collagen revealed the presence of all three components within all areas of the BM complex. In the meshes of the anastomotic BM network, extracellular vesicles were observed. Vesicles of similar size and appearance were also noted in the basal region of the transitional cells as well as in their basal-foot-like processes which extended deep into the meshes of the anastomotic network. While such extracellular vesicles may be derived from the transitional cells, as well as in their basal-foot-like processes which extended deep into the meshes of the anastomotic network. While such extracellular vesicles may be derived from the transitional cells, their functional significance is as yet unclear.