Stages of Embryonic Development for Alligator sinensis
摘要
The embryonic development course of Alligator sinensis \twas \ndivided into 28 stages,based upon observations on 150 A.sinensis \nembryos at varied embryonic day,according mainly to their external \nmorphology for early stages of embryos,such as body torsion,brain \nvesicles,sensory organs' morphology,limbs,branchial arches,facial \nprocesses,heart,skin and etc,and chiefly to the histological \ndifferentiation of their organs for late stages of embryos.It was found \nthat the embryonic day of A.sinensis was relatively in accordance with \nthat of A.mississippiensis for each of early 20 stages and was \ndifferent for late 8 stages presumably due to a different staging \nmethod.It was suggested that histological index about organ \ndifferentiation should be introduced into the late stages determination \nfor embryonic development of alligator and crocodiles,so as to make an \nagreement in staging method and to provide with basic documents and \nobjective references for subsequent studies on developmental biology of \nalligators and crocodiles.