The vulva is the external female genitalia, the structure of the vulva covers, and protects the deeper reproductive organs of the female, it is located in the groin area of the mammal, additionally it serves as the opening to the vagina, the image is that of a female dogs vulva
Oogenesis
Oogenesis is the formation/creation of the ovum (egg), also known as gametogenesis, and this is the females equivalent of spermogensis and it involves various stages of development of the immature ovum.
just like spermogensis the oogenesis involves meiosis, in the first part the primordial germ cells migrate from the endoderm yolk sac to the ovaries, with in the ovaries the germ cells divide in to oogonia. the oogonia are diploid cells they divide mitotically to produce millions of germs, some of these cells will degenerate, this is the process known as atresia, but a few go on to develop in to larger cells called primary oocytes, these enter the prophase of reduction division (meiosis 1), this stage is not completed until after puberty.
after polity in the female human gonadotropin (hormone) is secreted by the pituitary gland every month, the diploid primary oocyte completes reduction division (meiosis 1) and two haploid cells of equal sizes both containing 23 chromosomes, two chromatids each, are produced. the smaller cell produced by meiosis 1 is called the first polar body and the larger cell is know as the secondary oocyte. once the secondary oocyte has been formed it proceeds to the metaphase of equatorial division (meiosis II)and then stops, the place in which this is all taking place is the mature (Grafffian) follicle or vesicular ovarian follicle this will soon rupture releasing the secondary oocyte.
at equatorial division (meiosis II), or ovulation usually one of the secondary oocytes (with the first polar body) is expelled into the pelvic cavity, they are then collected by the uterine fallopian tubes (oviducts). if at this point fertilisation does not occur the secondary oocyte will degenerate however if sperm is present and one penetrates the oocyte fertilisation occurs, the secondary oocyte then splits in to two haploid cells of unequal size, the larger of these cells is the ovum (egg) the smaller one is the second polar body. nuclei of the sperm cell and the ovum unite, forming a diploid Zygote (Tortora& Grabowski, Reynolds, 1996), (Notarianni, 2011)