The developmental role of material derived from the nucleus (germinal vesicle) of mature ovarian eggs

Abstract

In the present study a biological activity test was developed for the material that is produced and stored in the oocyte nucleus (germinal vesicle) and later dispersed in the cytoplasm. The experimental method involved the transfer of germinal vesicle material to the blastocoels of mid to late blastulae. Intraspecific transfers of Rana pipiens germinal vesicle material to R. pipiens blastulae resulted later in enlarged head primordia. This suggests that germinal vesicle material is involved in axial organ formation. Interspecific transfers of R. catesbeiana or R. sylvatica germinal vesicle material to R. pipiens blastulae resulted in an inhibition of axial structures. This suggests that this material is species specific and is involved in the hybrid block to development. Germinal vesicle material loses its activity when heated at 55–60°C for 10 minutes. Intraspecific transfers of ovarian egg cytoplasm failed to produce a striking effect on development. However, interspecific transfers of R. catesbeiana cytoplasm to R. pipiens blastulae resulted in abnormal development. The abnormalities occurred later in development and were less severe than those produced by injections of germinal vesicle material.