Transplantations of blastula nuclei into activated eggs from the body cavity and from the uterus of Rana pipiens: II. Development of the recipient body cavity eggs

Abstract

Jellyless body cavity eggs, matured to the second meiotic metaphase, become activated when pricked with a glass needle. Transfers of blastula nuclei were made into such activated, nonenucleated, host eggs. The ability of the jellyless eggs to undergo normal cleavage and development was then compared with that of uterine host eggs. The results showed that body cavity eggs (82% of total) were as capable as uterine eggs (84%) of participating in genuine cleavage. Approximately equal proportions of body cavity eggs (69% of total) and uterine eggs (74%) also developed into complete blastulae. The majority of complete blastulae from uterine eggs developed normally through gastrulation and 65% attained the feeding stage. Most, but not all, of the complete blastulae from jellyless host eggs showed gastrular abnormalities ranging from a distinct retardation in yolk plug closure to incomplete, severe exogastrulation. The atypical gastrulation was found to be due not to intrinsic deficiencies in body cavity eggs, but mainly to other nonspecific defects (i.e., tight vitelline membranes, exovates, etc.). When the host eggs were artificially enclosed in jelly membranes, they underwent normal gastrulation and normal development to the feeding stage in most cases. In spite of the abnormal gastrulation in jellyless host eggs, many were able to regulate, and 45% of the complete blastulae developed to the feeding stage. Of the larvae from jellyless host eggs that were put out to feed, 71% metamorphosed into young froglets. The results show that normal development can be obtained from activated body cavity eggs, and therefore, a sojourn in the oviducts of the adult female is not necessary for complete development of anuran eggs to the young froglet stage.