Spermatozoa activation

Bailey, J.L. and Storey, B.T. (1994). Calcium influx into mouse spermatozoa activated by solubilized mouse zona pellucida, monitored with the calcium fluorescent indicator, fluo- 3. Inhibition of the influx by the influx by three inhibitors of the zona pellucida induced acrosome reaction Tyrphostin A48, pertussis toxin, and 3 -quinuclidinyl benzilate. Mol. Reprod. Dev. 39 297-308. 

The first cell cycle of the mouse embryo differs in many respects from the second and the following cell cycles. It is characterized by a long Gl phase that starts after the penetration of the spermatozoon or artificial activation of the oocyte. During this period the chromatin of the oocyte completes the second meiotic division and forms the female pronucleus. At the same time, in the fertilized egg, the highly condensed chromatin of the sperm nucleus decondenses and sperm-specific proteins, protamines, are replaced by histones. After the initial sperm chromatin... 

Microtubules occur in a single row below the plasma membrane of spermatozoa, although their distribution varies in different species (171). In H. diminuta and the Cyclophyllidea (Fig. 7.2), in general, they completely encircle the spermatozoon (171,212,835), often exhibiting helical periodicity. In Phyllobothrium gracile (Fig. 1.2(b)) the cortical microtubules may be confined to two demi-circles, lateral or external to the axonemes (561,564). The significance of these different distributions of microtubules in relation to potential sperm activity is not known. 

The cytoplasmic droplet in bull and ram serum is spherical with a diameter of approximately 3 /x. When viewed by phase contrast microscopy, it has a dark granulated region electron microscopy reveals that this region consists of vesicles and membranous or tubular structures. The concentration of acid phosphatase in droplets is 4.3 /xg nitrophenol liberated per hour per 10 particles, much higher than the activity, 0.2 /xg nitrophenol liberated per hour per 10 spermatozoa. Ribonuclease, acid protease, y3-glueuronidase showed similar ratios. Dott and Dingle (D14) submitted additional information which indicated that in the bull and, to a lesser extent in the ram, the lysosomal enzymes cease to be associated with the spermatozoon during its maturation. 

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