Saad A H, el-Deeb S, Mobarez M, Soliman M A
Zoology Department, Faculty of Science, Cairo University, Egypt.
Thymus. 1993 Sep;22(2):97-110.
Different stages of thymus morphogenesis and thymocyte differentiation have been studied at the ultrastructural level in the lizard, Chalcides ocellatus. On stage 36 of embryonic development, the thymus primordium was composed principally of undifferentiated epithelial cells and some lymphoid stem-cells. From stage 37 to 38, the lymphoid stem-cells differentiate into lymphoblasts and then transform into typical lymphocytes. A clasmotosis phenomenon seems to be involved in this transformation. In the developing cortical regions, lymphoblasts accumulated rapidly, stretching the epithelial cells which become stellate in shape. From stage 39 to 40, a phase of intense proliferation occurs and numerous lymphocytes die in the thymic tissue and are phagocytosed by macrophages. On stage 41, the presence of interdigitating cells in the medullary area completed cortico-medullary differentiation. On neonatal and juvenile lizards, small cortical thymocytes differentiated and the thymus possessed all characteristic of an adult thymus. Thus, at birth, the histogenesis of the lizard thymus was achieved and the only further modification consisted in a gain of weight.
在蜥蜴眼斑沙蜥中，已在超微结构水平上研究了胸腺形态发生和胸腺细胞分化的不同阶段。在胚胎发育的第36阶段，胸腺原基主要由未分化的上皮细胞和一些淋巴干细胞组成。从第37阶段到第38阶段，淋巴干细胞分化为淋巴母细胞，然后转变为典型的淋巴细胞。这种转变似乎涉及核碎裂现象。在发育中的皮质区域，淋巴母细胞迅速聚集，拉伸上皮细胞，使其呈星状。从第39阶段到第40阶段，发生强烈增殖阶段，胸腺组织中有大量淋巴细胞死亡并被巨噬细胞吞噬。在第41阶段，髓质区域出现交错突细胞，完成了皮质-髓质分化。在新生和幼年蜥蜴中，小皮质胸腺细胞分化，胸腺具有成年胸腺的所有特征。因此，在出生时，蜥蜴胸腺的组织发生完成，唯一进一步的变化是重量增加。
