中华大蟾蜍和花背蟾蜍间移核胚胎早期发育中染色体变化的研究

本研究以中华大蟾蜍和花背蟾蜍间正反核、质组合的移核胚胎为材料,对其三个不同发育阶段(囊胚晚期、原肠早期、原肠晚期)的移核胚胎染色体进行了组型分析。结果表明,无论以中华大蟾蜍囊胚细胞核作供体,花背蟾蜍去核未受精卵作受体的移核胚胎,还是相反组合的移核胚胎,在三个不同发育阶段,其染色体数目和形态均有变化,即:(1)表现出数目上有规律性的减少,一般减少2条、3条和4条;(2)出现异型染色体,如染色体断裂和双缢痕染色体;(3)表现出比较恒定的异常组型,即缺失第3染色体,多第4、5、6另染色体。在三个发育时期的分裂中期象中,具有2n=22者,中核组占40.3％-41.3％,花核组占52.3-53.1％。

CHANGES OF CHROMOSOMES DURING EARLY DEVELOPMENT OF THE EMBRYOS OBTAINED BY NUCLEAR TRANSPLANTATION BETWEEN BUFO BUFO GARGARIZANS AND B. RADDEI

Embryos from interspecies huclear transpla ntation between B. hufo gargarizans and B. rad-dei were used to analyse their chromosomes morphologically in three developmental stages (Late blastula, early gastrula and late gastrula). Either the transfer of nuclei from B. hufo gargar-izans blastula to enucleated B. raddei ova or vice versa gave the same results. There were changes in the number and morphology of their chromosomes as the nuclear transplanted embryos developed from blastulae to early gastrulae, and further to late gastrulae, namely (1) the number of their chromosomes reduced regularly, 1,3, or 4 less in general, (2) abnormal chromosomes appeared as some of them appeared splitted and some of them had two constrictions, (3) the abnormal karyotype was steady with the deletioa of No, 3 chromosome and the addition of No. 4, 5 and No. 6 chromosomes.