Study On The Histological Structure, The Expression Of Neuropeptides And Their Receptors During The Embryonic And Post Embryonic Development In The Thymus Of Duck

150 Tianfu ducks were divided into 30 groups as follows:17 groups in the embryonic period (one group per day from 12 to 28 embryonic days),13 groups after hatching(0,1,3,5,8,11,14,17,20,23,26,29,32 weeks).Using morphological methods, light microscopy, immunohistochemisty, the morphological and histological structures, neuropeptide and their receptors expression in the Tianfu duck thymus during the embryonic and post embryonic development were studied, meanwhile, discussing on the attribute of endocrine in the thymus. The results are as follows:(1) The developmental stages of the thymus were divided into two periods:the embryonic stage and the post-embryonic stage.The post-embryonic stage was divided into three periods:continued growth period (0～8weeks), the maturated and stable period (8～17weeks) and the regression period (20～32weeks). (2)The experiment data were analyzed with the SPSS, the results were as follows:The functional relation of the weight and the time, the thymus weight and time were taken on the sigmoid curve at embryonic stage and the cubic function at post embryonic stage. The functional relation of the thymus weight and the embryo weight were taken on the power function at embryonic stage. (3) The histological structure of the thymus was consistent with the growth parameters. The post-embryonic stage was divided into three periods:continued growth period (0～8weeks), the maturated and stable period (8～17weeks) and the regression period (20～32weeks). The histological structure of medulla was detected at 21 days embryonic stage, the diffuse thymic corpuscle was observed at 22～23days embryonic stage,thymic corpuscle at 24～25days embryonic stage.(4) The immunopositive reaction of calcitonin gene-related peptide (CGRP) occurred in the cortex of the thymic lobule from 26 days embryonic stage～8 weeks, in the medulla from 26 days embryonic stage～32 weeks and in vascular smooth muscle cells and endothelial cells; Calcitonin gene-related peptide type 1 receptor(CGRPR1) immunopositive reaction were located in the cortex and medulla,the vascular smooth muscle cells and endothelial cells from 22 days embryonic stage～32 weeks. The substance P(SP) immunopositive reaction cells were distributed in the cortex and medulla of the thymic lobule from 26 days embryonic stage～32 weeks,while the SP immunopositive reaction fibers were located in the capsule, interlobular septa and the vicinity of arterioles of the thymus from 3 to32 weeks after hatching; The immunopositive reaction of Substance P receptor (SPR) originally appeared in the medulla of the thymic lobule at 22 days embryonic stage, vascular smooth muscle cells, thymic corpuscle and the diffuse thymic corpuscle. NPY immunopositive reaction cells were found in the cortex and medulla from neonatal stage to 32 weeks after hatching. The NPY immunopositive reaction fibers were observed from 3 to 32 weeks after hatching. The cortex and medulla, the vascular smooth muscle cells and endothelial cells showed Neuropeptide Yl receptor (NPY1R) immunopositive reaction from 22 days embryonic stage to 32 weeks after hatching. Somatostatin (SS) immunopositive reaction cells were observed in the cortex from 20 to 32 weeks after hatching and in the medulla from 3 to 32 weeks after hatching. The immunopositive reaction particle of the Somatostatin receptorl (SSTR1) were detected in the medulla from 22 days embryonic stage to 32 weeks after hatching and also in endothelial cells. Chromogranin A (CgA) immunopositive reaction were detected only in the medulla from 26 days embryonic stage to 32 weeks after hatching. There was only statistic difference of the optical density in each group and place in the thymus.The results indicate:The four neuropeptide in the thymus of Tianfu duck showed the characteristics of age-related changes during the embryonic and post embryonic development. The immunopositive reaction cells of CGRP, SP, NPY, SS and their receptors were widely distributed in the thymus of Tianfu duck at different time, whose number showed the characteristics of age-related changes. The four kinds of neuropeptide were from the endocrine cells and the thymic epithelial cells.