#20
Date Lecture ________
x
Chapter 47 ~ Animal Development
Embryonic development/fertilization
x x x x x x x
Preformation~ until 18th century; miniature infant in sperm or egg At fertilization/conception: Acrosomal reaction~ hydrolytic enzyme action on egg jelly coat.... Fast block to polyspermy~ membrane depolarization prevents multiple fertilizations.... Cortical reaction~ release of calcium causes hardening of egg outer layer and creates a... Slow block to polyspermy and... Egg activation~ increases metabolic activity; protein synthesis
The Fertilized Egg & Cleavage
x x x x x x x
Blastomeres~ resultant cells of
cleavage/mitosis
Yolk~ nutrients stored in the egg Vegetal pole~ side of egg with
high yolk concentration
Animal pole ~ side of egg with
low yolk concentration
Morula~solid ball of cells Blastocoel~fluid-filled cavity in
morula
Blastula~hollow ball stage of
development
Cleavage
QuickTimetand Cinepak a decompressor are needed to see this picture.
Gastrulation
x x
x
Gastrula~ 2 layered, cup-shaped embryonic
stage
3 Embryonic germ layers:
Ectoderm~ outer layer; epidermis; nervous system, etc. Endoderm~ inner layer; digestive tract and
associated organs; respiratory, etc.
x
x
Mesoderm~skeletal; muscular; excretory, etc.
x x x
Invagination~ gastrula buckling process
to create the...
Archenteron~ primitive gut Blastopore~ open end of archenteron
Organogenesis: organ formation
x x x x x
Blastodisc~ cap of cells on
top of yolk
Primitive streak~
invagination of blastodisc
Neural tube~ beginning of
spinal cord
Somites~
vertebrae and skeletal muscles
Neural crest~ bones and
muscles of skull
Amniote embryos
x
Extraembryonic membranes:
yolk sac amnion chorion allantois
(support; circulatory function) (fluid-filled sac; protection) (placenta formation) (nitrogenous waste)