García Hernández M P, Lozano M T, Agulleiro B
Department of Cell Biology, Faculty of Biology, University of Murcia, Spain.
Anat Embryol (Berl). 1994 Dec;190(6):529-39. doi: 10.1007/BF00190103.
Several endocrine cell types were ultrastructurally characterized during the differentiation of the intestine and rectum of sea bass (Dicentrarchus labrax L.) larvae. Only one cell type (type I) was found in the posterior region of the undifferentiated gut of 5-day-old larvae (phase I). Types V and VI were found in both the intestine and rectum, types II, III and IV in the intestine, and types VII and VIII in the rectum of 9- and 12-day-old larvae (phase II), the rectum alone showing signs of functional differentiation. In phase III larvae, in which both the intestine and rectum were differentiated, types IX, X, XI, XII, XIII, XIV and XV were found in the intestine, only types X, XI and XII being seen in the rectum. Besides these, a new cell type, XVI, was observed in the intestine of 55- and 60-day-old larvae (phase IV), in which the digestive tract was completely differentiated. The endocrine cells appearing in phases I and II showed very scarce secretory granules and the ultrastructural features of undifferentiated cells. Some endocrine cell types in the earliest developmental stages were related to some of those found later. A maturational process of the endocrine cell types paralleled the differentiation of the intestine and rectum, with an apparent increase in the number of secretory granules accompanying organelle development.
在海鲈（Dicentrarchus labrax L.）幼体肠道和直肠的分化过程中，对几种内分泌细胞类型进行了超微结构特征分析。在5日龄幼体（阶段I）未分化肠道的后部区域仅发现一种细胞类型（I型）。在9日龄和12日龄幼体（阶段II）的肠道和直肠中均发现了V型和VI型，在肠道中发现了II型、III型和IV型，在直肠中发现了VII型和VIII型，仅直肠显示出功能分化的迹象。在阶段III幼体中，肠道和直肠均已分化，在肠道中发现了IX型、X型、XI型、XII型、XIII型、XIV型和XV型，在直肠中仅发现了X型、XI型和XII型。除此之外，在55日龄和60日龄幼体（阶段IV）的肠道中观察到一种新的细胞类型XVI型，此时消化道已完全分化。出现在阶段I和II的内分泌细胞显示出非常稀少的分泌颗粒以及未分化细胞的超微结构特征。最早发育阶段的一些内分泌细胞类型与后来发现的一些类型相关。内分泌细胞类型的成熟过程与肠道和直肠的分化平行，随着细胞器的发育，分泌颗粒的数量明显增加。
