CHAPTER 51 – VERTEBRATE DEVELOPMENT

Fertilization

Cleavage

Rapid division into smaller cells Amount of yolk Mammalian trophoblast contributes to the

placenta Cell to cell information

Positional Stem cells

Gastrulation

Folding to form germ layers Bilateral = 3 germ

layers Ecto, Meso, Endo

Protosome and deuterosome

Neurulation

Dorsal nerve cord forms

Neural crests migrate to control development Development is the

progressive restriction of gene expression

Early determination Commitment

Ontogeny recapitulates phylogeny

Embryonic development exhibits a progression of changes indicative of evolutionary origin

Changes were layered on top of each other

Human Development

~266 days = 3 trimesters 1st trimester

Implantation Mother/child placenta

Special gas exchange nourishment, filtration, drugs

Gastrulation, neurulation, organogesis, morphogenesis

3rd month = reflexes, facial expression, movement

2nd, 3rd trimester

Tremendous growth Feel kicks New neurons at 250,000/min

Birth and Postnatal Development Positive feedback

cause uterine contractions Estradiol, oxytocin

Expel placenta, cut cord

Lactation Less progesterone, more prolactin Oxytocin