Gheri Bryk S, Pacini P, Marchesi L
Boll Soc Ital Biol Sper. 1979 Feb 15;55(3):236-40.
The inner surface of the midgut of chicken embryos ageing between seven and fifteen days incubation has been examined by scanning electron microscope. In this period the surface of the mucous membrane undergoes significant morphological changes; in fact, while at seven days incubation it appears to be smooth and regular, in the following days it begins to show longitudinal folds increasingly higher, more numerous and complicated. Since eleven days incubation some folds take a zigzag appearance that progressively becomes more evident and extends to all the folds. In the mean time, the enterocytes undergo a gradual specialization and represent the only type of epithelial cells in this stage of development. Their apex until seven days incubation is dome-shaped, provided with short microvilli and separated from the surrounding cells by deep circular grooves. About thirteen days the apex appears to be less swollen, with longer and more numerous microvilli and bounded by microplicae arranged in an hexagonal disposition.
利用扫描电子显微镜对孵化7至15天的鸡胚中肠内表面进行了检查。在此期间，黏膜表面发生了显著的形态变化；事实上，孵化7天时，其表面看起来光滑且规则，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。从孵化11天起，一些褶皱呈现出锯齿状外观，且逐渐变得更加明显并延伸至所有褶皱。与此同时，肠上皮细胞逐渐特化，成为发育这一阶段唯一的上皮细胞类型。孵化7天时，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。大约13天时，顶端似乎肿胀减轻，有更长且更多的微绒毛，并由呈六边形排列的微褶界定。
