Ward S M, Torihashi S
Department of Physiology, University of Nevada School of Medicine, Reno, NV 89557, USA.
Cell Tissue Res. 1995 Oct;282(1):93-108. doi: 10.1007/BF00319136.
The development of the canine proximal colon from the completion of organogenesis through 43 days after birth was studied using light microscopy, immunofluorescence and electron microscopy. During this period the tunica muscularis increased in thickness from 42+/-6 microm in animals midway through the gestation period to 317+/-29 microm in animals 25-30 days old. This increase in thickness resulted from an increase in the number and size of smooth muscle cells in the circular and longitudinal muscle layers. The cross-sectional thickness of the circular muscle layer increased from 10+/-2 smooth muscle cells midway through the gestation period to 92+/-7 cells in animals 25-30 days old. The longitudinal layer increased in thickness from 1.5+/-1 cells in animals midway through the gestation period to 44+/-2 cells in animals 25-30 days old. Smooth muscle cells from both layers also increased in diameter and length. Ultrastructural and immunohistochemical studies suggested that many of the smooth muscle cells were undergoing development throughout the fetal period. Midway through the gestation period, the circular layer was positive for desmin-like immunoreactivity (D-LI), while both the circular and longitudinal layers were positive for vimentin-like immunoreactivity (V-LI). By birth, V-LI was suppressed in the circular and longitudinal layers, and both layers expressed D-LI. The enteric nervous system was already established midway through the gestation period, and submucosal and myenteric ganglia could be identified, although the chemical coding and mature morphology of neurons were incomplete. NADPH-diaphorase-positive neurons, indicating the expression of nitric oxide synthase, developed by the time of birth. Interstitial cells of Cajal (IC) could not clearly be identified midway through gestation, however, potential precursors to ICs were observed. Several classes of ICs were identifiable at birth.
利用光学显微镜、免疫荧光和电子显微镜，研究了犬近端结肠从器官发生完成到出生后43天的发育情况。在此期间，肌层厚度从妊娠期中期动物的42±6微米增加到25 - 30日龄动物的317±29微米。厚度的增加是由于环形和纵形肌层中平滑肌细胞数量和大小的增加。环形肌层的横截面厚度从妊娠期中期的10±2个平滑肌细胞增加到25 - 30日龄动物的92±7个细胞。纵形肌层厚度从妊娠期中期动物的1.5±1个细胞增加到25 - 30日龄动物的44±2个细胞。两层的平滑肌细胞直径和长度也增加。超微结构和免疫组织化学研究表明，许多平滑肌细胞在整个胎儿期都在发育。在妊娠期中期，环形层结蛋白样免疫反应性（D - LI）呈阳性，而环形和纵形层波形蛋白样免疫反应性（V - LI）均呈阳性。到出生时，环形和纵形层的V - LI受到抑制，两层均表达D - LI。肠神经系统在妊娠期中期就已建立，可以识别黏膜下和肌间神经节，尽管神经元的化学编码和成熟形态并不完整。出生时已发育出烟酰胺腺嘌呤二核苷酸磷酸黄递酶阳性神经元，表明一氧化氮合酶的表达。妊娠期中期无法清楚地识别Cajal间质细胞（IC），然而，观察到了IC的潜在前体。出生时可识别出几类IC。
