Ultrastructure of the Bovine Testis in Cattle (Bos taurus): New View

TL;DR

This study uses electron microscopy to examine the ultrastructure of bovine testes in calves and bulls, revealing developmental stages and cell types important for reproductive biology.

Contribution

The study identifies three distinct stages of seminiferous tubule development and describes two types of Sertoli cells in cattle.

Findings

Three distinct stages of seminiferous tubule development were identified in calves.

Two types of Sertoli cells, differing in electron density, were observed in cattle testes.

Morphological changes in pre-Sertoli cells during maturation were detailed using ultrastructural analysis.

Abstract

The detailed analysis of the structure of individual organs is necessary to understand the processes occurring within them. The complicated nature of male reproductive processes and the still insufficient knowledge of the structure of the male reproductive system prompted us to undertake the present research. In this study, using transmission electron microscopy (TEM) and histology staining, testes of sexually immature calves and reproductive bulls of the Polish Holstein-Friesian Black-and-White breed were analyzed. The obtained results were summarized and compared with previously published reports. The present manuscript presents complementary information on ultrastructure of seminiferous epithelium and interstitial tissue in cattle and provides an essential morphological background for further applied research.

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.

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