Characteristics of motor apparatus in testicular, epididymal and ejaculated spermatozoa. A study using demembranated sperm models

Morphological alterations of cytoplasmic organelles occur in the early stage of the cell fusion reaction induced by HVJ (Sendai virus) and these alterations are reversed in the late stage of the reaction. When the cells were treated with the virus at 37 °C for 3 min, the mitochondria became condensed, the cisternae of the endoplasmic reticula and Golgi stacks became highly distended, the inner space of the nuclear envelopes became enlarged, and the arrangement of 100 Å filaments became disordered. All these morphological changes were gradually reversed during further incubation at 37 °C and had been completely reversed by the end of the cell fusion reaction. These changes occurred at the time of interaction of the cell membrane with HVJ, and seemed to represent functional responses of the living cell to perturbation of the membrane resulting from its interaction with the virus.