Pacine P, Gheri Bryk S
Bull Assoc Anat (Nancy). 1979 Sep;63(182):317-22.
The inner surface of the midgut of chick embryos aged seven to fifteen days of incubation has been examined by scanning electron microscopy. At this period, the surface of the mucous membrane undergoes significant morphological changes; in fact, while at seven days of incubation it appears to be smooth and regular, in the following days it begins to show longitudinal folds increasingly higher, more numerous and complicated. After eleven days of incubation some folds take a zig-zag appearance that progressively becomes more evident and extends to all the folds. In the mean time, the enterocytes undergo a gradual differentiation and represent the only type of epithelial cells at this stage of development. Their apex until seven days of incubation is dome-shaped, provided with short microvilli and separated from the surrounding cells by deep circular grooves. At about thirteen days the apex appears to be less swollen, with longer and more numerous microvilli and delimited by microplicae arranged in a hexagonal disposition.
通过扫描电子显微镜检查了孵化7至15天的鸡胚中肠内表面。在此期间，粘膜表面发生了显著的形态变化；事实上，在孵化7天时，它看起来光滑且规则，而在接下来的几天里，它开始出现越来越高、越来越多且越来越复杂的纵向褶皱。孵化11天后，一些褶皱呈锯齿状，这种形态逐渐变得更加明显并延伸至所有褶皱。与此同时，肠上皮细胞逐渐分化，在发育的这个阶段代表唯一的上皮细胞类型。在孵化7天之前，它们的顶端呈圆顶状，有短微绒毛，并通过深环形凹槽与周围细胞分隔开。在大约13天时，顶端似乎肿胀程度减轻，有更长且更多的微绒毛，并由呈六边形排列的微褶界定。
