中华蟾蜍变态发育过程中消化道内分泌细胞的演变

目的 研究中华蟾蜍(Bufo gargarizans)变态发育过程中消化道5-羟色胺(5-HT)、生长抑素(SS)、胃泌素(GAS)、胰高血糖素(GLU)和胰多肽(PP)等5种胃肠激素内分泌细胞的分布密度、组织学定位及形态的演变. 方法 应用链霉卵白素-过氧化物酶(S P)免疫组织化学方法,每个变态发育时期取6只动物. 结果 5-HT细胞在中华蟾蜍变态发育各个时期消化道中均有分布,在孵出期起始出现于消化道中部,变态前期之后整个消化道均有分布,消化道中部5-HT细胞的密度显著增加(P＜0.05),从变态高峰期至幼蟾期,食道和贲门5-HT细胞的密度增加非常显著(P＜0.05);GAS细胞在幼蟾期才开始出现,主要集中于十二指肠,幽门处偶见;SS细胞在变态高峰期开始出现,仅在胃体和十二指肠偶有分布,幼蟾期分布于食道至空肠的各段,细胞密度显著增加(P＜0.05);GLU细胞在中华蟾蜍变态发育各个时期消化道中均有分布,变态前期之后消化道中部GLU细胞的分布密度增加非常显著(P＜0.05);PP细胞在变态发育的各个时期均未检测出.在孵出期,内分泌细胞主要位于固有层,呈圆形;变态早期和前期,主要位于单层柱状上皮细胞之间,呈圆形、椭圆形或梭形;变态高峰期,内分泌细胞主要位于腺泡细胞或上皮细胞基部,固有膜中偶见,呈椭圆形或锥形;在幼蟾期,主要位于腺泡细胞和黏膜上皮细胞之间,呈圆形或椭圆形,且个别细胞具有较长的胞突伸向肠腔. 结论 与其他两栖动物相比,中华蟾蜍消化道内分泌细胞在变态发育过程中的演变既有一定的共性,也存在着种间差异,内分泌细胞的演变与消化生理活动及个体生理活动的变化相适应.

Developmental changes of endocrine cells in the digestive tract of Bufo gargarizans during metamorphosis

Objective To study the developmental changes in distributional density, histological localization and morphology of five types of endocrine cells in the digestive tract of EM>Bufo gargarizans/EM> during metamorphosis with gut hormone antisera of 5-hydroxytryptamine (5-HT), gastrin (GAS), somatostatin (SS), glucagon (GLU) and pancreatic polypeptide (PP). Methods Six samples were used at every developmental stage. The endocrine cells of digestive tract were studied by immunohistochemical techniques of streptavidin peroxidase (SP) method. Results 5-HT cells were detected in the digestive tract at every stage of EM>Bufo gargarizans/EM> during metamorphosis, and they first occurred in the middle portion of the digestive tract at hatching stage. They were distributed in the whole digestive tract after prometamorphosis stage, and the density of these cells in the middle portion of the digestive tract increased significantly (EM>P/EM><0.05). The density of 5-HT cells significantly increased in the esophagus and cardia from metamorphosis climax stage to juvenile stage ( EM>P /EM><0.05); GAS cells first occurred at juvenile stage, and they were mainly distributed in the duodenum and occasionally detected in the pylorus; SS cells first appeared at metamorphosis climax stage and they were occasionally distributed in the fundus and duodenum. SS cells were distributed in every portion from the esophagus to the jejunum at juvenile stage, and the density of these cells significantly increased (P<0.05); GLU cells were detected in the digestive tract at every stage of Bufo gargarizans during metamorphosis and the distributional density of GLU cells in the middle portion of the digestive tract significantly increased (P<0.05) after prometamorphosis stage; PP cells were not detected at every stage of Bufo gargarizans during metamorphosis. At hatching stage，the endocrine cells were located in the lamina propria with round in shape; At premetamorphosis stage and prometamorphosis stage, they were located in the epithelium of the whole digestive tract with round, oval or shuttle in shape; At metamorphosis climax stage, they were located in the gastric gland or the basal portion of epithelium of mucosa of the digestive tract with oval or taper in shape and occasionally detected in the lamina propria; At juvenile stage, they were located in the gastric gland and the epithelium of mucosa of the digestive tract with round or oval in shape, and some cell had a long cytoplasmic process reaching into the digestive lumen. Conclusion Comparing with other amphibians, there are both common and specific features in the developmental changes of endocrine cells in the digestive tract of Bufo gargarizans during metamorphosis, and the developmental changes of endocrine cells are adaptive to the changes of the digestive physiological activities and the individual physiological functions.