ch 14 pt 2

• what does the enzyme phospholipase C-zeta do & what does it synthesize? where is it stored?


  it initiates the release of calcium from the oocyte E.R. through its ability to synthesize inosotol triphosphate brought by the sperm cytoplasm. plays a role in fertility
• what is the evidence that phospholipase C-zeta actually does what it claims it does

  studies of intracytoplasmic sperm injection a treatment for infertility
• when does the first cell division occur

  90 minutes after the prouclei meet
• pronuclei- 


  male and female haploid nuclei within a fertilized egg that fuse to form the diploid nucleus of the zygote
• by day 2 the embryo consists of?

  2 blastomeres
• by day 3?


  it's a loose confederation of about 8 cells THEN compaction occurs
• what surrounds the inner cell mass and the blastocoel 


  trophoblast
• how long is the human embryo transcriptionally inert after fertilization

  3 days
• "maternal-to-zygotic-transition"


  when control of gene expression shifts from being derived from stored mRNAs within oocyte to being controlled by new transcription from zygotic genome
• what gene is expressed in the outer cells of the 16-cell embryo and what is the gene "characteristic of"?

  GATA3 gene, characteristic of the trophoblast
• how long does it take the embryo to reach the uterus and what structures help it get there

  a week, the cilia in the oviducts
• what does the trophoblast cells secrete at day 5? what does it do and how does it accomplish it?


  sodium ions; osmotic entry of water from the extracellular environment creating the blastocoel
• what does the sodium ions and osmotic entry do to the trophoblast cells

  flattens them against zona pellucida
• what is the role of hatching enzymes? what regulates them?

  digest the zona pellucida regulated by progesterone from corpus luteum
• "hatching"


  gets rid of the shell to burrow into the uterus
• what happens when hatching occurs too late?


  embryo will not attatch to uterus and then blastocyst will be eliminated from the mother
• ectopic pregnancy


  early mammalian embryo implants and begins to grow within an area of the body outside of the uterus