When first formed, the ovary only has an established epithelium at its base or hilum. Later, an epithelium is established around the rest of the ovary. To examine this further, we conducted scanning electron microscopy of the surface of bovine fetal ovaries and immunohistochemistry of ovarian cross-sections. From the earliest time point, the cells on the surface of the base or hilum of the ovary were cuboidal. On the remainder of the ovary, the surface was more irregular. By mid-development, the surface was covered completely with either a stratified or simple epithelium of cuboidal cells. Clefts were observed in the surface and appeared to form due to the expansion of stroma surrounding each open ovigerous cord, elevating the areas surrounding each cord, while leaving the opening of the cord to form the base of each cleft. The continued expansion of the surrounding stroma below the surface appeared not only to close the ovigerous cords from the surface but to compress the clefts into the shape of a groove. Later, most of the ovarian surface was covered with a simple cuboidal epithelium. The changes to the ovarian surface during fetal development coincide with the remodeling of the stroma and cords below.

中文翻译：

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胎儿发育过程中牛卵巢表面上皮的形成。


卵巢最初形成时，仅在其基部或卵巢门处有已形成的上皮。随后，在卵巢其余部分周围形成上皮。为了进一步研究这一点，我们对牛胎儿卵巢表面进行了扫描电子显微镜检查，并对卵巢横截面进行了免疫组织化学检查。从最早的时间点开始，卵巢基部或卵巢门表面的细胞呈立方形。在卵巢的其余部分，表面更加不规则。到发育中期，表面完全被立方形细胞的分层或简单上皮覆盖。在表面观察到裂缝，并且似乎是由于围绕每个开放的产卵索的基质扩张而形成的，抬高了每个索周围的区域，同时留下了索的开口以形成每个裂缝的底部。表面以下周围基质的持续扩张似乎不仅将产卵索与表面封闭，而且将裂缝压缩成凹槽的形状。后来，大部分卵巢表面被简单的立方上皮覆盖。胎儿发育过程中卵巢表面的变化与下方基质和索带的重塑一致。