PDF(Pubmed)
Abstract：
The purpose of this study was to analyze the ultrastructure of the testes of sexually immature calves and reproductive bulls of the Polish Holstein-Friesian Black-and-White breed. Utilizing TEM, this study identified three distinct stages of seminiferous tubule development in calves, characterized by varying shapes, distributions, and arrangements of individual cells. In immature animals, early developing spermatocytes, prespermatogonia, and pre-Sertoli cells were observed within the seminiferous tubules. In sexually mature bulls, all cells of the spermatogenic series were observed, situated on a thin, multilayered basal lamina, which forms characteristic undulations. An abundant smooth endoplasmic reticulum was observed in the cytoplasm of spermatogonia in both groups of animals, forming characteristic membranous swirls. In adult bulls, spermatogonia maintain contact with each other through numerous cytoplasmic bridges and cell connections, forming small spaces with visible microvilli between them. The ultrastructural analysis facilitated the identification of morphological changes occurring during the maturation of pre-Sertoli cells, transitioning from a large euchromatic nucleus to a nucleus in which the formation of characteristic vesicles and tubules could be observed. It should also be emphasized that two types of Sertoli cells, namely dark and light electron-dense cells, can be found in cattle. These cells differ from each other, indicating that they may perform different functions. The widespread recognition of the presence of two types of Sertoli cells in cattle will undoubtedly contribute to a better understanding of the processes occurring within the testes and provide a basis for further research in this area.
摘要：
这项研究的目的是分析波兰荷斯坦-弗里斯黑和白品种的性未成熟小牛和生殖公牛睾丸的超微结构。利用TEM，这项研究确定了小牛生精管发育的三个不同阶段，以不同的形状为特征，分布，和单个细胞的排列。在未成熟的动物中，早期发育的精母细胞，前精原细胞,在生精小管内观察到前支持细胞。在性成熟的公牛中，观察到生精系列的所有细胞，坐落在一个薄的，多层基底层，形成特征性的起伏。在两组动物的精原细胞的细胞质中都观察到了丰富的平滑内质网，形成特征性膜状漩涡。在成年公牛中，精原细胞通过许多细胞质桥和细胞连接彼此保持接触，形成小空间，它们之间有可见的微绒毛。超微结构分析有助于鉴定前支持细胞成熟过程中发生的形态变化，从大的常色核过渡到可以观察到特征性囊泡和小管形成的核。还应该强调的是，两种类型的支持细胞，即黑暗和明亮的电子致密细胞，可以在牛身上找到。这些细胞彼此不同，表明他们可能执行不同的功能。对牛中两种类型的支持细胞的存在的广泛认识无疑将有助于更好地了解睾丸内发生的过程，并为该领域的进一步研究提供基础。
