扬子鳄胚胎发育分期

本文基于150例不同胎龄的扬子鳄胚胎，将扬子鳄胚胎发育过程分成28个时期。早期胚胎主要以外部形态如体节、体曲程度、脑泡、感觉器官、附肢、鳃弓、颜面部突起、心脏、皮肤等作为分期标准；晚期胚胎主要以器官发育的组织学指标为分期依据。发现在前20个时期中，每个时期的胎龄与密河鳄的很一致，后8个时期的胎龄与密河鳄有差异。分析认为，鳄类晚期胚胎的分期依据应增加器官发育的组织学指标，以便使不同鳄类的胚胎发育有一致的分期标准，为鳄类发育生物学后续研究提供基础资料。

Stages of Embryonic Development for Alligator sinensis

The embryonic development course of Alligator sinensis was divided into 28 stages,based upon observations on 150 A.sinensis embryos at varied embryonic day,according mainly to their external morphology for early stages of embryos,such as body torsion,brain vesicles,sensory organs' morphology,limbs,branchial arches,facial processes,heart,skin and etc,and chiefly to the histological differentiation of their organs for late stages of embryos.It was found that the embryonic day of A.sinensis was relatively in accordance with that of A.mississippiensis for each of early 20 stages and was different for late 8 stages presumably due to a different staging method.It was suggested that histological index about organ differentiation should be introduced into the late stages determination for embryonic development of alligator and crocodiles,so as to make an agreement in staging method and to provide with basic documents and objective references for subsequent studies on developmental biology of alligators and crocodiles.