Fertilization can happen on day 14, 15, or 16. (0-48 hours after ovulation) the realization of the mothers 2• needs to happen in the upper1/3 of her fallopean tube The fathers spermatozoa has 23 chromosomes, 23 centromeres, and is a haploid (1n). Roughly 50-100 spermatozoa out of millions survive and have potential to penetrate the 2•. The spermatozoa has enzymes on the tip of the head to help it peirce into the membrane of the secondary oocyte. The head is aero-dynamic do its easier to swim, and so that it can easily pierce the 2•. Its also the part of the spedmatozia that holds the DNA and the only part that actually enters the 2•. The body is round and loaded with mitochondria for energy. The flagellas main purpose is for swimming. After the 3• has been pierced, it creates a "poison Sheila" that says "one spermatozoa has already pierced and is moving in, the rest of you need to die." The head of the spermatozoa enters the 2• and releases it's body and its flagella. The 2• performs meosis II and becomes an ootid as the head moves in. The ootid creates a polar body and releases it. The ootid and its polar body both have 23 chromosomes, 23 centromers, and they are haploids(1n).
The chromosomes from the spermatozoa and the ootid pair up and create a zygite that has 46 chromosomes, 46centromerez 23 pairs, and 22 homologous pairs. Homologous pairs are two chromosomes with similar make-up. The 23rd pair is the pair that distinguishes gender. In this zygote the pair is XY which means it will be a male. The zygote is round so it can easily travel down the fallopean tube. The fallopean tube performs slight parastalsus and the mucus inside also helps the zygote travel through. As the zygote migrates down the fallopean tons, it performs rapid mitosis. This includes prophase, metaphase, anaphase, and telepahse. The cells still stay interconnected as it tumbles down.
At the end of the fallopean the the solid cluster of 300 stem cells becomes a murula. There is no growth, just division.
At day 5 in uteri the murula enters the uterus and floats around for 2-3 days. As the murula floats, it hallows out in the center and it continues to divide. It hallows out so that it can create space for the body cavities. This hollowed out cluster of 1000 stem cells is called a blastula.
On day 7 in uteri the blastula implants into the endometrium, which is the lining of the uterus. Once it implants it can start to grow and divide because it can now access food from the mother. The ideal place for the blastula to implant is either on the left or right side of the uterus. As soo. As it implants the ventral and dorsal sides are set.
On day 17 in uterus 5,000 stem cells find in on themselves a preserving the space. Thus is now called a gastrula.
On day 18 in utero, the stem cells differentiate. The genetic coded are turned on and cells are told what the are going to become. They create four layers: 1 is a protective layer. It's not part of the child, but it is made out of baby cells(ambiotic sac and umbilical cord). The other three are primary germ layers which become the…