prenatal development is the period from fertilization of the ovum to birth.
period from fertilization of the ovum to birth?
prenatal development
fertilization marks the first germinal stage of embryonic development. when semen is released into the vagina, the spermatozoa travel through the cervix and body of the uterus and into the fallopian tubes where fertilization usually takes place. many sperm cells are released with the possibility of just one managing to adhere to and enter the thick protective layer surrounding the egg cell (ovum). the first sperm cell to successfully penetrate the egg cell donates its genetic material (dna) to combine with the dna of the egg cell resulting in a new organism called the zygote. the term "conception" refers variably to either fertilization or to formation of the conceptus after its implantation in the uterus, and this terminology is controversial.
prenatal development
during ovulation, the ovum travels down the fallopian tubes to the uterus. these extend about from both sides of the uterus. finger-like projections at the ends of the tubes brush the ovaries and receive the ovum once it is released. the ovum then travels for three to four days to the uterus. after sexual intercourse, sperm swim up this funnel from the uterus. the lining of the tube and its secretions sustain the egg and the sperm, encouraging fertilization and nourishing the ovum until it reaches the uterus. if the ovum divides after fertilization, identical twins are produced. if separate eggs are fertilized by different sperm, the mother gives birth to non-identical or fraternal twins.
human sexuality