Some Effects of x-rays on Dividing Cells in the Testis and Bone Marrow of the Marsupial Potorous Tridactylus

Summary

Six male specimens of the marsupial Potorous tridactylus (2n = 13) were irradiated with 50 to 320 r of x-rays. Serial biopsies of testis and bone marrow were performed, some before irradiation to provide control material, and others at intervals up to 16 days after. Standard Feulgen squash preparations were made for cytological examination. Additional information was obtained from whole mounts of long tubule segments in which the spatial relationships of the various cell-types were retained. These provided information relating cellular distribution to the phase of the spermatogenic wave.

Extensive destruction of spermatogonia was observed, and evidence was obtained that this takes place in two separate periods, one before and the other after the first post-irradiation mitosis. Cells with deficient chromosome sets were not found in mitosis, and the second phase of cell-destruction probably represents their elimination.

The bone-marrow cells showed more chromosome breakage and a shorter mitotic cycle than the spermatogonia.