Secondly, a fear that came from a lack of awareness of the need for sperm donation, what it entails and and who it is for.
The Amazon molly reproduces gynogenetically, i.e. its eggs contain an unreduced set of chromosomes, that need the sperm of one of the sister species Poecilia mexicana or Poecilia latipinna as a mechanical trigger to start development [ 20- 22].
Zinc is normally needed for maturation of sperm, but in the concentration used in the serum, it destroys the seminiferous tubules.
In addition, an intact acrosome is needed for sperm to interact with the female tract and ova [40], so a certain proportion of sperm need to retain acrosome integrity for fertilization to occur.
It may be that the IVF procedures as used routinely, which are essentially designed to maximize blastocyst yields rather than for detecting differences in fertilizing ability between batches of sperm, need to be modified.
In this vein, the need for the inhibition of sperm fertilizing ability in the distal epididymis (i.e., the requirement for capacitation) may be to enable restricted sperm entry into the oviduct.
Finally, 5 days are needed for sperm to reach the tail of epididymis for ejaculation (Zhu et al. 2006).
Recent intraspecific studies have shown that the degree of elongation of the sperm head has the strongest impact upon sperm swimming velocity [ 25], because it reduces the degree of drag and thus the energy needed for sperm movement [ 51].
Although sperm of all species can be sorted with high purity, achieving pregnancies with the low numbers of sperm needed for commercial application remains particularly elusive in swine.
The unwillingness of a female mammal to mate when mature eggs are not present prevents loss of sperm needed to preserve the species.
