1. Chapter 47
Animal Development

2. Fertilization Egg sends out chemical signals for sperm to find it
Sperm capacitation refers to the physiological changes spermatozoa must undergo in order to have the ability to penetrate and fertilize an egg.
Hyaluronic acid – on sperm, eats away the cumulus cells
Cumulus cells – were follicle cells earlier
Zona pellucida – membrane under cumulus cells, has proteins:
ZPI – don’t need to know, it’s a linker
ZPII – second protein; encourages the egg to take in the sperm
ZPIII – first protein; sperm binds and acrosome comes out and eats through zona

3. Preventing Polyspermy
Cortical granules act as IP3 system (release calcium) when sperm makes it in
Cuts off ZPIII
Changes the composition of the zona (so another acrosome can not penetrate because its enzymes wouldn’t work)

4. Specializing the cells
After Fertilization
Cell division 1
Differentiation
Specializing the cells 2
Morphogenesis
Forming the embryo 3

5. Cleavage
Grey crescent – lots of magical substances/ information

6. Experiment
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7. Nervous system development
Notochord tells ectoderm to become nervous system
First organ system to develop
Neural plate forms neural tube
Defects
Spina Bifida
Anencephaly

8. Malformations/Birth Defects
Most body systems are developed during the first three months of pregnancy, so birth defects can develop very early
Thalidomide
Drug in the 1950s and 1960s
Inhibited long bone formation, so babies were born with very short arms/legs
X-rays
Could kill primordial germ cells
Fetal Alcohol Syndrome