Liu Xuelai, Lui Vincent Chi Hang, Wang Huan, Ye Mao, Fan Rentao, Xie Xianghui, Li Long, Jin Zhe-Wu
Department of Surgery, Capital Institute of Pediatrics affiliated Children Hospital, Beijing, China.
Department of Surgery, School of Clinical Medicine, The University of Hong Kong, Hong Kong, Hong Kong.
J Dev Orig Health Dis. 2023 Feb;14(1):24-32. doi: 10.1017/S2040174422000253. Epub 2022 Aug 4.
The sequential occurrence of three layers of smooth muscle layers (SML) in human embryos and fetus is not known. Here, we investigated the process of gut SML development in human embryos and fetuses and compared the morphology of SML in fetuses and neonates. The H&E, Masson trichrome staining, and Immunohistochemistry were conducted on 6-12 gestation week human embryos and fetuses and on normal neonatal intestine. We showed that no lumen was seen in 6-7 gestation week embryonic gut, neither gut wall nor SML was developed in this period. In 8-9 gestation week embryonic and fetal gut, primitive inner circular SML (IC-SML) was identified in a narrow and discontinuous gut lumen with some vacuoles. In 10 gestation week fetal gut, the outer longitudinal SML (OL-SML) in gut wall was clearly identifiable, both the inner and outer SML expressed α-SMA. In 11-12 gestation week fetal gut, in addition to the IC-SML and OL-SML, the muscularis mucosae started to develop as revealed by α-SMA immune-reactivity beneath the developing mucosal epithelial layer. Comparing with the gut of fetuses of 11-12 week of gestation, the muscularis mucosae, IC-SML, and OL-SML of neonatal intestine displayed different morphology, including branching into glands of lamina propria in mucosa and increased thickness. In conclusions, in the human developing gut between week-8 to week-12 of gestation, the IC-SML develops and forms at week-8, followed by the formation of OL-SML at week-10, and the muscularis mucosae develops and forms last at week-12.
人类胚胎和胎儿中三层平滑肌层（SML）的顺序出现情况尚不清楚。在此，我们研究了人类胚胎和胎儿肠道SML的发育过程，并比较了胎儿和新生儿SML的形态。对妊娠6 - 12周的人类胚胎和胎儿以及正常新生儿的肠道进行苏木精 - 伊红（H&E）染色、马松三色染色和免疫组织化学检测。我们发现，妊娠6 - 7周的胚胎肠道未见管腔，此期间肠壁和SML均未发育。在妊娠8 - 9周的胚胎和胎儿肠道中，在狭窄且不连续的肠管腔中发现了原始的内环平滑肌层（IC - SML），伴有一些空泡。在妊娠10周的胎儿肠道中，肠壁的外纵平滑肌层（OL - SML）清晰可辨，内外平滑肌层均表达α - 平滑肌肌动蛋白（α - SMA）。在妊娠11 - 12周的胎儿肠道中，除了IC - SML和OL - SML外，黏膜肌层开始发育，这可通过发育中的黏膜上皮层下方的α - SMA免疫反应性显示出来。与妊娠11 - 12周胎儿的肠道相比，新生儿肠道的黏膜肌层、IC - SML和OL - SML呈现出不同的形态，包括向黏膜固有层腺体分支以及厚度增加。总之，在妊娠8至12周的人类发育肠道中，IC - SML在第8周发育并形成，随后OL - SML在第10周形成，黏膜肌层最后在第12周发育并形成。
