Chapter 47 development 12 01 2015 FIG 47 2 Embryonic development Fertilization o Capacitation changes in the sperm can be anatomical expose receptors on the sperm o Where is the egg o Egg sends out a chemical signal to call sperm o 99 of sperm won t make it into the uterus o FIG 47 5 o Cumulus cells granulosa line the eggs o Zona pellucida surrounds mammalian eggs o Cell membrane o Hyaluronic acid released by sperm to help it move through cumulus cells Receptors on sperm head that binds to the zona ZP 1 ZP 2 ZP 3 proteins associated with the zona Sperm comes in and binds to ZP 3 this blows the acrosome releasing the hydrolytic enzymes Turns sideways to bind to ZP 2 now able to go into the egg o Sperm has to go in through microvilli not around the area of the nucleus and then waits on the egg to finish meiosis o Cortical reaction Once sperm is in the egg Sets up an IP3 mechanism releases calcium Calcium causes the granules to move to the surface and dump out their contents they will cut off all the ZP 3 s cause a change in chemical composition in zona acrosomal enzymes can no longer eat away zona won t allow for polyspermy Cleavage o These cells skip G1 G2 o FIG 47 6 o Lots of cell division o Differentiation of structure and function Make specialized cells genetics o Morphogenesis to take shape o Blastula blasusis ball of cells with hole in the middle o In a frog cell gray crescent is formed first cleavage divides this into two cells o FIG 47 22 experiment When gray crescent isn t allowed to cleave only one baby is formed Gastrulation o If you don t gastrulate you won t live o Study from the 1920 s o Ectoderm roll into the inside to make endoderm mesoderm at blastopore to create the archenteron gut o Tell the cells above to make the neural tube o If there are two places of gastrulation a second neural tube will be made o First system to develop is the nervous system Organogenesis We develop like chickens FIG 47 8 How does nervous system develop FIG 47 13 Comes from ectoderm Sink down and make neural plate Pull it down and make a tube Bring in more ectoderm to cover the tube Neural crest cells form in between Somites made in the mesoderm If this doesn t happen on one end the brain skull and head will not form If it happens on the other end spina bifida Folic acid reduces the incidence of neural tube defects SRY sex determining region on the Y Tells the genes to make testes Makes testosterone and anti mullerian hormone Testosterone also adds external Anti mullerian hormone Tells mullerian ducts to go away Mullerian ducts become uterus Mullerian Wolffian Become other male internal parts two ducts that everyone has No SRY ovary Tell wolffian to go away External female 12 01 2015 12 01 2015