Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Department of Internal Medicine, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Anat Histol Embryol. 2021 Nov;50(6):1026-1033. doi: 10.1111/ahe.12746. Epub 2021 Oct 13.
Sheep have been used as translational models of human postnatal testicular development. However, the morphometric features of the normal developing testis in sheep embryos have not been previously investigated using stereology. The objective of the present work was to establish normal quantitative parameters for fetal testicular tissue components in sheep, using unbiased design-based stereological methods. Twenty-four sheep embryos were divided into four gestational age groups (9-11, 12-14, 15-17 and 18-20 weeks of gestation) on the basis of the embryos' crown-rump length. Isotropic, systematic uniform random sections of the left testes were obtained by employing the orientator method. Testicular total volume, the absolute and proportional volumes occupied by the seminiferous tubules and interstitial tissue, as well as the seminiferous tubule length, were estimated using the point-counting system and the unbiased counting frame principle. All the parameters, with the exception of the interstitial tissue's fractional volume, gradually increased along with gestational age, with the maximum increase especially seen in the late fetal stages. The proportional volume of the interstitial tissue, on the other hand, showed a decreasing trend along with increasing gestational age. The absolute volume of the testes, of the seminiferous tubules and of the interstitial tissue, and the length of the seminiferous tubules showed a significant (p< 0.05) positive linear correlation with gestational age. Several similarities were observed with human testicular embryogenesis. The stereological data emerging from the present study might prove useful as basic contribution to the fields of andrology and embryology and stimulate further research in these areas.
绵羊已被用作人类产后睾丸发育的翻译模型。然而，绵羊胚胎正常发育睾丸的形态计量学特征以前尚未使用无偏设计立体学方法进行研究。本研究的目的是使用无偏设计基于体视学的方法，为绵羊胎儿睾丸组织成分建立正常的定量参数。根据胚胎的头臀长，将 24 只绵羊胚胎分为四个胎龄组（9-11 周、12-14 周、15-17 周和 18-20 周）。采用定向器法获得左侧睾丸各向同性、系统均匀随机切片。使用点计数系统和无偏计数框原理估计睾丸总体积、生精小管和间质组织的绝对和相对体积以及生精小管长度。除间质组织的分数体积外，所有参数均随胎龄逐渐增加，尤其是在胎儿晚期增加明显。另一方面，间质组织的相对体积随胎龄的增加呈下降趋势。睾丸、生精小管和间质组织的绝对体积以及生精小管的长度与胎龄呈显著正线性相关（p<0.05）。与人类睾丸发生存在一些相似之处。本研究得出的体视学数据可能有助于男科和胚胎学领域，并激发这些领域的进一步研究。
