DIFFERENTIAL DECONDENSATION OF CLASS-I (RAT) AND CLASS-II (MOUSE) SPERMATOZOA NUCLEI BY PHYSIOLOGICAL CONCENTRATIONS OF HEPARIN AND GLUTATHIONE

The kinetics of sperm nuclear decondensation induced by the action of physiological concentrations of heparin and glutathione was studied by comparing two rodents: the rat, with very stable protamine P1 contain ing chromatin (class I nuclei), and the mouse, with protamine P1 and p rotamine P2 (class II nuclei). Sperm suspensions were incubated at dif ferent temperatures (37, 40; 43, and 46 degrees C) in media while keep ing a constant concentration of either heparin or GSH and increasing c oncentrations of the other reagent. Spermatozoa nuclei without any tre atment incubated for 72 h appear densely condensed. Swelling of mouse spermatozoa nuclei was observed after 30 min of incubation in the pres ence of efficient concentrations of heparin-GSH. The extent of this ti me lag was significantly reduced at higher temperatures. This behavior was also observable in the rat, but required time lags of 3-4 h. Elec tron microscopy observations showed that the pattern of nuclear decond ensation was different in both animal species. Mice sperm nuclei initi ates its decompaction by the peripheral regions and this behavior rema ins until late stages of decondensation. On the contrary, rat spermato zoa nuclei decondense initially at the central part of the nuclei whil e the periphery remains condensed, showing numerous residues of densel y packed chromatin. In both cases, the chromatin is organized into ''h ub-like'' nuclear bodies joined by a network of chromatin fibers.