-
Fertilization
only nucleus enters
whole sperm enters
fast block to "polyspermy"
slow block
- - sea urchin
- -mammals
- -triggers opening of Na+ channels in egg cellmembrane
- -1. ERrelases Ca2+ in egg cell 2. cortical granuels move and fuse w/plasma membrane 3. fertilization envelope
-
totipotent
pluripotent
morphogenisis
Development(6 steps)
- -"total potential" to be any cell
- -many potential to be a cell
- -embryo takes form
- 1. gamete formation 2.fertilization 3.cleavage(cell division,mitosis)4.Gastrulation(morphogenesis) 5. organ formation(differentiation)
- 6. Growth and tissue formation(differentiation)
-
Cleavage
solid ball of cells
Cell signaling
blastula
gastrula(ation)
archenteron, blastopore, dorsal lip
- -mitotic division of zygote w/o growth , uneven cytoplasm division, seals developmental fate of cells, cells get smaller w/division
- -morula
- -figure where cell destined,molecules determine what genes on and off
- - hollow fluid filled ball, successive divisions form it, polarity up v. down established
- -gut and tissue layers develop(rearrange blastula to form a 3 layered embryo w/ primitive gut)
- -forms endoderm embryonic gut, at sperm penetration point, organizing center for development
-
germ layers
1. ectoderm
2. endoderm
3. mesoderm
-ceolom
-apoptosis
- 1. external, skin, nervous system
- 2. internal, digestive system, liver, gull bladder, pancreas
- 3. middle tissue-muscle, circulatory, bone, reproductive
- -fluid filled space between gut and outer wall , organs move independently of eachother
- -programmed cell suicide by proteins
|
|
