In the wood mouse Apodemus sylvaticus, sperms aggregate in 'trains' that are better able to fertilize eggs because they are more capable of navigating the viscous environment of the female reproductive tract.
In marine invertebrates and sea urchins, the rise in pH to about 7.2–7.6 activates ATPase which leads to a decrease in intracellular potassium, and thus induces membrane hyperpolarization.
[3] The change in cell volume which alters intracellular ion concentration can also contribute to the activation of sperm motility.
[4] In most animals, this distal centriole act as a shock absorber preventing the microtubules filaments from moving at the axoneme base.
When spermatozoa reach the isthmic oviduct, their motility has been reported to be reduced as they attach to epithelium.
The bending of the flagellum is due to subsequent cycles of dynein arm attachment, generation of force and detachment on the B subunit.
The binding of the axoneme is the result of the presence of a resistance to the microtubule sliding generated by dynein.
The first event is the activation of a Na+/HCO3 − (NBC) co-transporter and the regulation of HCO3 − /Cl− by SLC26 transporters, that bring to an increase in HCO3 − levels.
The effects of aging on semen quality is summarized below based on a study of 1,219 subjects:[11] [Min-Max] [0-88] [0-95] [0-83] [0-84] [0-59]