Cavicchia Juan Carlos, Fóscolo Mabel, Ibañez Jorge, Lillig Christopher, Capani Francisco
Instituto de Histología y Embriología "Dr. Mario H. Burgos" (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
Biocell. 2011 Dec;35(3):81-9.
Junctional devices in Sertoli cells conform the blood-testis barrier and play a key role in maturation and differentiation of germ cells. The spacial distribution of ectoplasmic specializations of Sertoli cells was studied by beta-actin immunolabelling, using laser confocal and transmission electron microscopy. For confocal microscopy, beta-actin immunolabelling of ectoplasmic specializations was studied over the background of either prosaposin or glutaredoxin immunolabelling of the Sertoli cytoplasm. Labelling was found near the basal lamina, surrounding early spermatocytes (presumably in leptotene-zygotene) or at one of two levels in the seminiferous epithelium: (1) around deep infoldings of the Sertoli cell cytoplasm, in tubular stages before spermiation, and (2) in the superficial part of the seminiferous epithelium, in tubular stages after or during spermiation. For transmission electron microscopy, beta-actin immunolabelling of ectoplasmic specializations was also used. Ectoplasmic specializations were found at two different levels of the seminiferous epithelium. We also used freeze fracture to analyze the characteristics of tubulo-bulbar complexes, a known component of apical ectoplasmic specializations. Also, these different approaches allowed us to study the complex arrangement of the actin cytoskeleton of Sertoli cells branches, which surround germ cells in different stages of the spermatogenic cycle. Our results show a consistent labelling for beta-actin before, during and after the release of spermatozoa in the tubular lumen (spermiation) suggesting a significant role of the actin network in spermatic cell differentiation. In conclusion, significant interrelations among the beta-actin network, the junctional complexes of the blood-testis barrier and the ectoplasmic specializations were detected at different stages of the seminiferous cycle.
支持细胞中的连接装置构成血睾屏障，并在生殖细胞的成熟和分化中起关键作用。利用激光共聚焦显微镜和透射电子显微镜，通过β-肌动蛋白免疫标记研究了支持细胞外质特化的空间分布。对于共聚焦显微镜，在支持细胞胞质的prosaposin或谷氧还蛋白免疫标记背景下研究外质特化的β-肌动蛋白免疫标记。在基膜附近、围绕早期精母细胞（可能处于细线期-偶线期）或在生精上皮的两个水平之一发现标记：（1）在支持细胞胞质的深褶周围，在精子发生前的管状阶段，以及（2）在生精上皮的浅表部分，在精子发生后或期间的管状阶段。对于透射电子显微镜，也使用了外质特化的β-肌动蛋白免疫标记。在外质特化在生精上皮的两个不同水平被发现。我们还使用冷冻断裂来分析微管-球复合体的特征，微管-球复合体是顶端外质特化的已知组成部分。此外，这些不同的方法使我们能够研究支持细胞分支的肌动蛋白细胞骨架的复杂排列，这些分支围绕着生精周期不同阶段的生殖细胞。我们的结果显示，在管腔中精子释放（精子发生）之前、期间和之后，β-肌动蛋白有一致的标记，表明肌动蛋白网络在精子细胞分化中起重要作用。总之，在生精周期的不同阶段检测到β-肌动蛋白网络、血睾屏障的连接复合体和外质特化之间存在显著的相互关系。
