Huang Xu-Gen, Wu Xiao-Bing
Key Laboratories on Conservation and Use of Important Biological Resources of Anhui Province, College of Life Science, Anhui Normal University, Wuhu 241000, Anhui Province, China.
World J Gastroenterol. 2005 Sep 21;11(35):5498-505. doi: 10.3748/wjg.v11.i35.5498.
To clarify the types, regional distributions and distribution densities as well as morphological features of gastrointestinal (GI) endocrine cells in various parts of the gastrointestinal track (GIT) of four reptiles, Gekko japonicus, Eumeces chinensis, Sphenomorphus indicus and Eumeces elegans.
Paraffin-embedded sections (5 mum) of seven parts (cardia, fundus, pylorus, duodenum, jejunum, ileum, rectum) of GIT dissected from the four reptiles were prepared. GI endocrine cells were revealed by using immunohistochemical techniques of streptavidin-peroxidase (S-P) method. Seven types of antisera against 5-hydroxy-tryptamine (5-HT), somatostatin (SS), gastrin (GAS), glucagon (GLU), substance P (SP), insulin and pancreatic polypeptide were identified and then GI endocrine cells were photomicrographed and counted.
The GI endocrine system of four reptiles was a complex structure containing many endocrine cell types similar in morphology to those found in higher vertebrates. Five types of GI endocrine cells, namely 5-HT, SS, GAS, SP and GLU immunoreactive (IR) cells were identified in the GIT of G. japonicus, E. chinensis and S. indicus; while in the GIT of E. elegans only the former three types of endocrine cells were observed. No PP- and INS- IR cells were found in all four reptiles. 5-HT-IR cells, which were most commonly found in the pylorus or duodenum, distributed throughout the whole GIT of four reptiles. However, their distribution patterns varied from each other. SS-IR cells, which were mainly found in the stomach especially in the pylorus and/or fundus, were demonstrated in the whole GIT of E. chinensis, only showed restricted distribution in the other three species. GAS-IR cells, with a much restricted distribution, were mainly demonstrated in the pylorus and/or the proximal small intestine of four reptiles. GLU-IR cells exhibited a limited and species-dependent variant distribution in the GIT of four reptiles. SP-IR cells were found throughout the GIT except for jejunum in E. elegans and showed a restricted distribution in the GIT of G. japonicus and S. indicus. In the GIT of four reptiles the region with the highest degree of cell type heterogeneity was pylorus and most types of GI endocrine cells along the GIT showed the peak density in pylorus as well.
Some common and unique features of the distribution and morphology of different types of GI endocrine cells are found in four reptiles. This common trait may reflect the similarity in digestive physiology of various vertebrates.
阐明日本壁虎、中国石龙子、印度棱蜥和四线石龙子这四种爬行动物胃肠道各部位胃肠道内分泌细胞的类型、区域分布、分布密度以及形态特征。
制备从四种爬行动物解剖得到的胃肠道七个部位（贲门、胃底、幽门、十二指肠、空肠、回肠、直肠）的石蜡包埋切片（5微米）。采用链霉亲和素 - 过氧化物酶（S - P）法免疫组织化学技术显示胃肠道内分泌细胞。鉴定了七种针对5 - 羟色胺（5 - HT）、生长抑素（SS）、胃泌素（GAS）、胰高血糖素（GLU）、P物质（SP）、胰岛素和胰多肽的抗血清，然后对胃肠道内分泌细胞进行显微拍照并计数。
四种爬行动物的胃肠道内分泌系统是一个复杂的结构，包含许多形态与高等脊椎动物中发现的相似的内分泌细胞类型。在日本壁虎、中国石龙子和印度棱蜥的胃肠道中鉴定出五种胃肠道内分泌细胞，即5 - HT、SS、GAS、SP和GLU免疫反应（IR）细胞；而在四线石龙子的胃肠道中仅观察到前三种内分泌细胞类型。在所有四种爬行动物中均未发现PP - 和INS - IR细胞。5 - HT - IR细胞最常见于幽门或十二指肠，分布于四种爬行动物的整个胃肠道。然而，它们的分布模式彼此不同。SS - IR细胞主要见于胃，尤其是幽门和/或胃底，在中国石龙子的整个胃肠道中均有显示，在其他三种物种中仅呈局限性分布。GAS - IR细胞分布非常局限，主要见于四种爬行动物的幽门和/或近端小肠。GLU - IR细胞在四种爬行动物的胃肠道中呈现有限且依赖物种的变异分布。SP - IR细胞在除四线石龙子空肠外的整个胃肠道中均有发现，在日本壁虎和印度棱蜥的胃肠道中呈局限性分布。在四种爬行动物的胃肠道中，细胞类型异质性最高的区域是幽门，并且沿胃肠道的大多数类型的胃肠道内分泌细胞在幽门处也显示出密度峰值。
在四种爬行动物中发现了不同类型胃肠道内分泌细胞分布和形态的一些共同和独特特征。这种共同特征可能反映了各种脊椎动物消化生理学的相似性。
