cleavage Echinoderm include Echinoidea. sea urchins; 5-7 devisions (128)
organogenesis-frog Neural crest -> skull, etc. Archenteron from endoderm.
germ_layers Prefix ecto: outer, external; epi: above, top.
embryonic REVU epiblast, hypoblast -> yolk sac. Prefix tropo: turning, change; epi: above, top. Trophoblast implants by digesting enzymes.
fertilization QH442.2 .C743 2002: Creation#23:30 woman egg donor, Judson's skin cells thru zona pellucida (glycoprotein) - 32:30

acrosomal depolarized: Na ions flow in;
Cortical reaction -> slow block to polyspermy sea urchin.
gastrulation-urchin Vegetal pole: has yolk (not in mammals).
embryonic2 Placenta also contains mesoderm.
organogenesis-chick Chickens hatch 21 days.

SQ: 1=a       3=e  
AQ: 1=e  2=a  3=b  4=e  5=d  6=b  7=d  8=c
CQ:                     5=a  6=c  7=c  8=a           17=a

0. Vitelline (yolk of an egg) layer: meshwork of extracellular matrix molecules under jelly coat.
1. Somites: give rise to segmental structures such as vertebrae and skeletal muscle.
2. Neural crest along border where neural tube pinches off from ectoderm, form peripheral nerves, teeth, skull bones, many other cell types.
3. Archenteron: primitive gut, open end of archenteron is blastopore, will become anus.
4. Frog: yolk–laden cells im vegetal hemisphere of embryo.
5. Allantois: precursor of umbilical cord
6. Blastocyst: mammalian version of blastula