Role of Ca2+ and cAMP in rat spermatogenesis--ultrastructural evidences.

On the ultrastructural level, the role of Ca2+ and cAMP in the rat spermatogenesis was studied. Using a K-pyroantimonate method for intracellular localization of Ca2+, precipitates were found within (i) the vesicular component of the chromatoid body, (ii) vesicular elements of the trans-Golgi area including coated vesicles, (iii) smooth endoplasmic reticulum vesicles and cisterns accompanying the perinuclear (manchette) microtubules, and (iv) mid-piece mitochondria of germ and Sertoli cells. The results suggest a close relationship between the Ca(2+)-containing smooth endoplasmic reticulum and the control of microtubule assembly within microdomains. Theophylline (a cAMP-phosphodiesterase inhibitor) treatment of rats (96 mg/kg daily i.p. over 5 days) caused a significant increase of (a) the GERL-related coated vesicles and (b) the number of manchette microtubules.