MORPHOGENETIC MOVEMENTS OF NORMAL AND GASTRULA-ARRESTED HYBRID AMPHIBIAN TISSUES

Abstract

1. Explant systems have been constructed to test the abilities of isolated normal (Rana pipiens, Rana sylvatica) and hybrid (R. pipiens ♀ x R. sylvatica ♂) gastrular tissues to undergo activities surrogative of certain morphogenetic movements occurring in gastrulating embryos. 2. Evidence has been obtained to show that hybrid ventral ectoderm can carry out normal morphogenetic movements. On the other hand, there is some indication (see (10), (21), (22), (27) and (28)) that hybrid yolk endoderm is abnormal; and there is definite evidence ((23)-(26)) to show that the behavior of hybrid presumptive notochord is deviant from that of normal presumptive notochord. 3. Some tentative explanations are offered in morphological terms for the failure of hybrid embryos to gastrulate past Stage 10.