Expression And Significance Of The Diffuse Neuroendocrine Cells In The Development Of Fetal Thymus

Objective:To observe the expression and the distribution of the diffuse neuroendocrine cells in fetal thymus and to discuss its biologic significance in fetal thymus.Methods:27 specimens of fetal thymus (from 15^th week to 40^th week of gestation) were obtcined and stained by immunohitochemical staining and immunofluorescent double staining. Neuroendocrine cells were identified by immunohistochemical staining of chromogranin A (CgA) and neuron specific enolase (NSE). Somatostatin (SS) and vasoactive intestinal peptide(VIP) were used to identify the inclusions of neuroendocrine cells. The density of the cells of neuroendocrine cells was assessed by micro-image analyzing system.Results:1. CgA and NSE positive cells were expressed in fetal thymus from 15^th week to 38^th week. The number of them increased with the gestational weeks until the 28^th week and then decreased thereafter. And they were not detected in fetal thymus from 39^th week to 40^th week. CgA and NSE immunoreactive cells mainly were located at in the medullary of fetal thymus. And they displayed a simple round,oval shape and triangle shape around Hassall's body or between thymocytes. The positive cells of SS and VIP both expressed during fetal thymus, especially actived most during 17^th and 18^th week and the characteristic of their expression were the same as that of the positive NSE and CgA cells. Meanwhile, the thymic epithelial cells of Hassall's body were stained by immunohistochemical staining of VIP and SS.2. It was shown that the positive cells of CgA, NSE, SS and VIP were active in the fetal thymus by immunofluorescent double staining, and the distribution and expression of them followed a similar pattern of that by immunohistochemimial...