differentiate the egg, as found in the ovary, oviduct and after fertilization?

Answer 1

Well, depends on what species you're referring to, but generally speaking... in the ovaries, an egg is usually immature. During ovulation, the immature egg develops more within a follicle, which eventually ruptures, expelling the egg and releasing a burst of hormones. The mature egg travels along the oviduct (or fallopian tubes, in a mammal), developing as it travels in preparation for fertilization and either implantation in the uterus (in a mammal) or develoment of a thick membrane or shell (in reptiles, birds and fish). After fertilization, the egg changes its morphology both chemically and physically, to prevent other spermatozoa from trying to double-fertilize the egg.