THE CAUSE OF THE DECREASED NUMBER OF PRIMORDIAL GERM-CELLS IN ALBINO XENOPUS RESIDES NOT IN THE MICROENVIRONMENT BUT IN THE PRESUMPTIVE PGC

The number of primordial germ cells (PGC) in albino tadpoles of Xenopu s is significantly decreased as compared with that of the wild-type. W hether the decreased number of PGC is caused by the presumptive PGC (p PGC) themselves or the micro-environment surrounding those cells in th e albino, or both was investigated in the present study. [H-3]thymidin e-labeled pPGC of wild-type and albino were implanted into unlabeled, host neurulae of wild-type or albino and wild-type, respectively Label ed PGC in the genital ridges of experimental tadpoles were examined by autoradiography. There were no significant differences in the proport ion of tadpoles with labeled PGC and in the average number of those PG C between the albino and wild-type tadpoles, into which wild-type pPGC had been implanted. The proportion in wild-type tadpoles with albino pPGC was much lower than that in wild-type tadpoles with wild-type pPG C. These results suggest that the pPGC of the albino and not the micro -environment are responsible for the decreased number of PGC.