在马,怀孕的特征是高水平的母体雌激素,主要由后代性腺内的间质组织产生,与生理性性腺增生有关,这在其他物种中并不常见。然而,由于缺乏大量数据,在马妊娠中,对性腺发育和增生的早期阶段的详细结构-功能了解仍然难以捉摸.这项研究的目的是通过解剖学方法描述19种早期马胚胎和胎儿(妊娠20-140天)的生殖器官发育,组织学,体视学,和免疫组织化学,特别关注性腺增生和间质组织发育。在两种性别中都观察到性腺增生与相似量的间质细胞,但仅在发育的早期阶段(第40-90天)。令人惊讶的是,增生程度较高,以大量富含间质细胞的区域为特征,从妊娠90天开始在胎儿卵巢中观察到。另一个新的方面是,平行于间质细胞的增生,在卵巢中可以看到更早熟和明显的生殖细胞分化,特征在于DAZL和OCT蛋白免疫标志物的较早峰值和降低。总之,妊娠90天后,胎儿睾丸的增生和间质组织程度降低,这表明存在一种更有效的机制,即雌激素前体的合成是胎儿两性之间的结构或生理差异,这需要进一步调查。
In horses, pregnancy is characterized by high levels of maternal estrogens that are produced largely by the interstitial tissue inside the gonads of the offspring, associated with a physiological gonadal hyperplasia, that is uncommon in other species. However, a detailed structural-functional understanding of the early stages of gonadal development and hyperplasia has remained elusive in horse pregnancy because of the lack of substantial data. The goal of this study was to describe the genital organs\' development in 19 early horse embryos and fetuses (days 20-140 of gestation) of both sexes by means of anatomy, histology, stereology, and immunohistochemistry, with a specific focus on gonadal hyperplasia and interstitial tissue development. Gonadal hyperplasia with similar amounts of interstitial cells was observed in both sexes, but only during the early stage of development (days 40-90). Surprisingly, a higher degree of hyperplasia, characterized by larger amounts of interstitial cell-rich areas, was seen in fetal ovaries from 90 days of gestation onwards. Another novel aspect was that parallel to the hyperplasia of the interstitial cells, a much more precocious and pronounced differentiation of germinal cells was seen in the ovary, characterized by an earlier peak and decrease of DAZL and OCT protein immune markers. In conclusion, a reduced degree of hyperplasia and interstitial tissue in the fetal testis after 90 days of gestation suggests the existence of a more efficient mechanism regarding the synthesis of estrogen precursors as a structural or physiological difference between both fetal sexes, which warrants further investigation.