Developmental potentialities of blastema cell nuclei of the Mexican Axolotl.

Abstract

AbstractDuring amphibian limb regeneration, differentiated cells contribute to the formation of a blastema. Cells once incorporated into the blastema are identical in their morphological appearances. This investigation is a test of the developmental potentialities of blastema cell nuclei as revealed by means of nuclear transplantation.When blastula cell nuclei are injected into enucleated eggs, approximately 80–90% of the test eggs cleave. Over half of the cleaved eggs form regular blastulae. Of the regular blastuae 60% form post‐neurula embryos.The initial experiment with regenerating cells involved the ijection of two to three blastema cell nuclei from a seven‐day‐old regenerate into test eggs. The blastema cells were obtained from a white Axolotl (dd) and the test eggs were laid by a dark Axolotl (Dd). Of some 35 eggs injected, five partial and two regular blastulae were obtained. One of the regular blastulae was sacrificed after 24 hours of development, and part of its tissue was grafted on an embryo of the genetic composition DD. When the host started to develop its pigmentation, the graft developed as a white patch, thus indicating the genetic nature of the graft was that of transplanted blastema cell nucleus. Subsequently single blastema cell nuclei from seven‐ to sixteen‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were able to promote development of post neurula embryos.