Hyh mouse harboring a point mutation in the Napa gen coding for αSNAP is the first example of a fertility problem directly related to a factor necessary for the general mechanism of regulated secretion that is specifically affecting the acrosome reaction.
A variety of explanations of these trends have been offered, for example the hypothesis of fertility adjustment to the relative well-being of particular cohorts (Easterlin 1968), the theory of the second demographic transition (Lesthaeghe & van de Kaa 1986), or the economic analysis of opportunity costs of childbearing (Becker 1991).
Chimpanzees, for example, have a similar pattern of fertility to people.
Examples of direct benefits include increased fertility, fecundity, resource provision, parental provision, breeding territories or a reduction in predation and harassment risks [ 3].
Availability of a positive example or a favorable family history of fertility at AMA was often reported as a reassuring factor that increased women's perceived ability to conceive at AMA and to have a successful pregnancy.
In a society where infertility in women and maternal age at birth of the first child are increasing, the unfavourable effects of fertility drugs (for example, a possible small increase in risk of ovarian cancer) should be balanced against the physical and psychological benefits of a pregnancy made possible only by the use of these drugs.
This may also be appropriate in the present situation if, for example, the fertility of the soil as a potential source of morbidity is best or worst at a particular location.
For example, DR often increases lifespan at the expense of fertility [ 1].
Farmland is a more ancient example: the fertility of soil can be increased by prudent cultivation.
"On the other hand, cryopreservation, the preservation of cells and tissues by freezing, is now a well-known process in certain branches of medicine, for example the preservation of sperm and embryos as part of fertility treatment.
