Equine uterine development, including endometrial histogenesis, begins prenatally and is completed postnatally. Little is known about this process in the horse. Uterine tissue was acquired from 38 foals, ranging in developmental age from gestational day (GD) 300 to postnatal day (PND) 180, for assessment of endometrial histogenesis. Patterns of endometrial cell proliferation were evaluated by multispectral imaging of uterine tissue sections stained immunofluorescently for Ki-67. Labeling index (LI, % labeled cells) for Ki-67 was calculated for each endometrial cell compartment (luminal epithelium, glandular epithelium, stroma). Histologically, nascent endometrial glands were present in all pre- and postnatal uterine tissues. Overall, Ki-67 LI increased (P < 0.0001) from the pre-to postnatal periods, and was higher (P < 0.0001) in epithelium as compared to stroma. Postnatally, endometrial Ki-67 LI increased (P < 0.0001) from week 1 to week 24. Our findings confirm that, in contrast to neonatal patterns of uterine development described for domestic ungulates, equine endometrial histogenesis begins prenatally, marked by the appearance of uterine glands as early as GD 300. Epithelial proliferation associated with maturation of the equine endometrium is pronounced by postnatal week 24.

中文翻译：

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胎儿晚期和产后时期的马子宫内膜发育

马的子宫发育，包括子宫内膜组织发生，在出生前开始并在出生后完成。关于马的这个过程知之甚少。从 38 只小马驹获得子宫组织，发育年龄从妊娠日 (GD) 300 到产后日 (PND) 180，用于评估子宫内膜组织发生。通过对 Ki-67 免疫荧光染色的子宫组织切片进行多光谱成像评估子宫内膜细胞增殖的模式。计算每个子宫内膜细胞室（腔上皮、腺上皮、基质）的 Ki-67 标记指数（LI，标记细胞百分比）。在组织学上，新生的子宫内膜腺体存在于所有产前和产后子宫组织中。总体而言，Ki-67 LI 从产前到产后增加（P < 0.0001），并且更高（P < 0. 0001) 在上皮细胞中与基质相比。出生后，子宫内膜 Ki-67 LI 从第 1 周到第 24 周增加（P < 0.0001）。我们的研究结果证实，与家养有蹄类动物描述的新生儿子宫发育模式相反，马子宫内膜组织发生在出生前开始，以子宫的出现为标志腺体早在 GD 300。与马子宫内膜成熟相关的上皮增殖在出生后第 24 周显着。