Synaptinemal complexes in primary spermatocytes of the mouse: the effect of elevated temperature and some observations on the structure of these complexes in control material

Summary

In the present study the “life cycle” of synaptinemal complexes has been ascertained for C57B1 male mice. These complexes appear in stage VIII and disappear in stage IX of the subsequent cycle. In the mouse, pairing of single cores is prompt; after stage X single cores are very rare. The appearance of cores in leptotene in the normal mouse is almost synonymous with pairing. No prolonged or clearly defined stage has been seen in which all the cores are single. Likewise the disappearance of cores with pachytene of stage X is abrupt. It was observed that in heat-treated material the occurrence of cores is depressed. This is true (1) in cores that must have been preformed before the treatment was started — suggesting destruction of cores, (2) in cores formed during the progress of the experiment, and (3) in spermatocytes originating from cells that must have been subjected to heat several cell generations before they were observed. In all cases “asynapsis” is expressed as a depression of the total core number as well as a percent increase in the unpaired cores. The phenomenon of induced asynapsis is suggested to reflect a change in outer hydrogen bonds of the respective chromosomes.