Author information Article notes Copyright and License information Disclaimer. The same protocol was followed for control pairs, though in their case the same fish were always replaced together. Some traits or characteristics display continuous variationa range human egg fertilization sex determ in Leicester phenotypes that cannot be easily divided into clear categories.
Biology of Reproduction96 3— Follicle stimulating hormone FSH levels.
In that case, spermatozoa surround the egg cell in an attempt to fertilize it. Gray's Anatomy. Washington, D. Retrieved The development of sexual differences begins with the XY sex-determination system that is present in humans, and complex mechanisms are responsible for the development of the phenotypic differences between male and female humans from an undifferentiated zygote.
Stages of natural fertilization. January
Download as PDF Printable version. Zaira Salvador. Cell Cycle. A human fetus does not develop its external sexual organs until seven weeks after fertilization.
Int Rev Cytol. Here we use egg production to evaluate female mate preference in the zebrafish, Danio rerio. Although association time has been shown to correlate with mating preference in some species, in others it does not Fuller The transcriptomic basis of oviposition behaviour in the parasitoid wasp Nasonia vitripennis.