REPROLAB, Faculdade de Veterinária, UFRGS, Porto Alegre, RS, Brazil.
REPROLAB, Faculdade de Veterinária, UFRGS, Porto Alegre, RS, Brazil; Facultad de Veterinaria, UDELAR, Montevideo, Uruguay.
Theriogenology. 2019 Jul 1;132:106-112. doi: 10.1016/j.theriogenology.2019.04.006. Epub 2019 Apr 14.
Rapid endometrial adaptations occur with the embryo entering the uterus to create a receptive uterine environment, which is essential for the conceptus' development. The aim of this study was to demonstrate ultrastructural and histological changes of the endometrium at day 5 after ovulation in cyclic and inseminated mares. Mares were daily examined by transrectal palpation and ultrasonographic examination of the reproductive tract until ovulation was detected. In the first cycle, endometrial biopsies from 10 cyclic mares (Cyclic group) were collected on day 5 post-ovulation. In the second cycle, the same mares were inseminated with fresh semen from a fertile stallion (Inseminated group). Intrauterine biopsies were collected on day 5 post-ovulation, and according to sampling moment, inseminated mares were subdivided into two subgroups, those sampled at day 5-5.5 (n = 5) and those sampled at day 5.5-6 (n = 5). Biopsy samples were analyzed through scanning electron microscopy and light microscopy. Inseminated group presented an increase in glandular diameter, decrease in ciliated cell population, and an increase in lymphocyte population, compared to Cyclic group. No differences were observed between both experimental groups in number of micro-ciliated polygonal cells, percentage of flat or protruded cells in the epithelium, amount of secretion over the epithelium, glandular density, glandular luminal diameter, height of the glandular epithelium, amount of intraglandular secretion, blood vessel diameter and number of eosinophils and neutrophils. No differences in any of the variables were detected between subgroups from inseminated mares. These facts lead to the hypothesis that there is some sort of signaling to prepare and adapt the uterus to maintain pregnancy even before embryo arrival. There is also evidence to support an alternative hypothesis suggesting that all of the above mentioned are inflammatory events, resulting from a previous inflammation due to residual seminal effects. The results here presented lead to the conclusion that significant ultrastructural and histological changes of the endometrium occur on day 5 post ovulation in inseminated mares.
胚胎进入子宫会引起子宫内膜迅速适应，从而为胚胎发育创造一个接受的子宫环境，这对胚胎的发育至关重要。本研究旨在展示排卵后第 5 天循环和授精母马的子宫内膜的超微结构和组织学变化。通过直肠触诊和生殖道超声检查，每天检查母马，直到检测到排卵。在第一个周期中，从 10 头循环母马（循环组）中采集排卵后第 5 天的子宫内膜活检。在第二个周期中，用来自健康种马的新鲜精液对同一头母马进行授精（授精组）。排卵后第 5 天采集宫内活检，并根据采样时间将授精母马细分为两个亚组，即第 5-5.5 天（n=5）和第 5.5-6 天（n=5）采样的母马。通过扫描电子显微镜和光学显微镜分析活检样本。与循环组相比，授精组的腺管直径增加，纤毛细胞数量减少，淋巴细胞数量增加。在微纤毛多角形细胞数量、上皮平坦或突出细胞的百分比、上皮表面分泌物量、腺密度、腺腔直径、腺上皮高度、腺内分泌物量、血管直径以及嗜酸性粒细胞和中性粒细胞数量方面，两组实验之间均无差异。在授精母马的亚组之间，没有检测到任何变量的差异。这些事实导致了这样一种假设，即存在某种信号，以使子宫做好准备并适应，即使在胚胎到达之前也要维持妊娠。还有证据支持另一种假设，即所有上述情况都是炎症事件，是由于残留精液的影响导致先前炎症引起的。这里呈现的结果得出结论，在授精母马中，排卵后第 5 天子宫内膜会发生显著的超微结构和组织学变化。
