FAILURE TO IDENTIFY A SPERMATOGONIAL CHALONE IN ADULT IRRADIATED TESTES |
| |
Authors: | G R Cunningham Claire Huckins |
| |
Institution: | Departments of Medicine and Cell Biology, Baylor College of Medicine, and Houston VA Hospital, Houston, Texas, U.S.A. |
| |
Abstract: | The adult irradiated rat testis was used as a model system to confirm the existence of a spermatogonial chalone. Rats were given 330 rad whole body 60Co irradiation, a dose which selectively destroys most of the spermatogonial population except for the radioresistant As stem cells. 11 days after irradiation, when spermatogonial numbers were minimal, the rats were injected with a testicular or liver extract prepared from normal adult rats, or with saline. Each group received a total of four injections given at 4 hr intervals. 2 hr before death, the animals were injected with 3H]TdR. Testicular DNA was isolated and the incorporation of 3H]TdR was determined. The mean ± s.e. ct/min per μg DNA in rats given testicular extract (9·38 ± 0·94) was no different than in those receiving liver extract (10·43 ± 2·01) or saline (7·23 ± 0·69). Autoradiographic studies indicated that variability in counts within or between groups could be attributed to variations in the number of pre-leptotene spermatocytes which incorporated 3H]TdR for the meiotic divisions. Quantitatively, there were no differences between groups in terms of the numbers of A spermatogonia, their labelling indices, or mitotic activity. Therefore, the presence of a spermatogonial chalone could not be demonstrated using crude extracts from normal testes in this irradiated model. |
| |
Keywords: | |
|
|