Morphometric Description of Spermatogonial Stem Cells and Expansion of Their Clonal Derivatives - Male Germline Stem Cells Developmental and Regenerative Potential - page 96

Fig. 4.4 Numbers of A s , A pr , and A al spermatogonia throughout the stages of the cycle of the
seminiferous epithelium in the Chinese hamster. Data are from Lok et al. ( 1982 )

26 in 101xC3H mice to 60 per 1,000 Sertoli cells in C3H mice (Tegelenbosch and
de Rooij 1993 ; Huckins and Oakberg 1978 ).

4.6 Cell Cycle Characteristics of A s,p r, al Spermatogonia

As first shown by Huckins and Kopriwa, it is possible to carry out autoradiography
on whole mounts of seminiferous tubules (Huckins and Kopriwa 1969 ). Using this
technique after 3 H-thymidine administration, cell cycle times have been established
of all types of spermatogonia in the rat (Huckins 1971a, d ) and the Chinese hamster
(Lok and de Rooij 1983a ; Lok et al. 1983 ). Again advantage has been taken of the
wave of spermatogenesis and the synchronous behavior of the A1-B spermatogonia.
Shortly after injection of the 3 H-thymidine all A1-B spermatogonia in S-phase incor-
porate this precursor and become labeled. Observing whole mounts of autoradio-
graphs of seminiferous tubules, one can see sharply defined tubule areas in which
cells of one of the generations of A1-B spermatogonia are all labeled, meaning that
in that specific area the various clones of differentiating spermatogonia synchro-
nously traverse the S phase. These areas with a labeled generation of A1-B sper-
matogonia are interspaced by large areas in which these cells are unlabeled as they
had been in G1, G2, or M phase at the time of the injection of 3 H-thymidine. In the
latter areas the labeled spermatogonia are exclusively clones of A s,pr,al spermatogonia