animal development i where it all begins… 01-15.03
TRANSCRIPT
Animal Development I
Where it all begins…
01-15.03
Animal Development I
When does development begin?Where is the beginning of a circle!?*
Where should we start?
What is gametogenesis?Where do sperm come from?Where do eggs come from
Some Gamete questions…
Why are gametes required for sexual reproduction?
What makes gametes different from somatic cells?What is ploidy?Remember meiosis
Fig 12.5
Some Gamete questions…
How have gametes become specialized?Hint: think morphology…
More about gametes Where do sperm come from?
Why do mammals have testes?What is the structure of testes? (fig
59.11, 13)What are germ cells?What are stem cells?
How many sperm form from each germ stem cell?
More about spermatogenesis
What is the progression from germ stem cell to sperm?What is a germinal cell (aka germ cell stem
cell)What is a primary spermatocyteWhat is a secondary spermatocyteWhat are spermatids?What are spermatozoa?What do sertoli cells do?
More about gametes…
What about eggs?What is their major cargo?
Nutrients, cytoplasmic determinants, maternal chromosomes
How do they protect themselves?What sort of structural adaptations do they
display? What is a jelly coat? What is a vitelline membrane? What is a zona pelucida?
More about eggs
How valuable are they? How many are made?When are they made available?
How do they find the sperm? Who finds whom?Are eggs motile?
More about eggs…
What are cytoplasmic determinants?mRNA, protein, other moleculesWhere are they located? When are they depositied?
What is oogenesis?How are they distributed?
What happens during cell division?What do they do?
What is polarity?
Fig 17.14
More about eggs
Where do eggs come from?Why ovaries?What is the structure of ovaries? (fig
59.16)
More about eggs
Where do eggs come from?What cellular process is involved?
Meiosis again…How many eggs form from each germ
stem cell?
More about eggs
How does egg structure differ between organisms?Jelly coat (sea urchin) vs. zona
pellucida (mammal)No cell layer (sea urchin) vs. granulosa
(mammal)Yolk differences
More later…
Back to fertilization
What are model organisms?
What are the models for studying fertilization?
The rules of engagement…(fig 60.3)What does the sperm encounter first?How can it get through the jelly coat?
More about fertilization
What is penetration (aka. the acrosome reaction)? (fig 60.3)Remember the acrosome?
Remember the jelly coat/zona pellucida?What happens when the acrosome
encounters jelly coat?What are the signals?What are hydrolytic enzymes?What do they do?
More about fertilization More acrosomal reaction…
How does the sperm penetrate jelly coat?What is the acrosomal process
What happens at the vitelline membrane?Why are receptors important?
What happens next?Sperm and egg membranes fuseHOORAY!!!
More about fertilization What is the situation?
How many eggs are available?How many sperm are available?Only ONE winner!
What is polyspermy? How is polyspermy prevented?
Fast block to polyspermySlow block to polyspermy
The fast block to polyspermy
What is membrane potential? What happens to the membrane
potential upon sperm fusion? How does depolarization prevent
polyspermy? How long does the fast block to
poplyspermy last?
The slow block to polyspermy
How does the slow block work?What is signal transduction?
What are second messengers?Why do we need them?
More about the slow block
Where are intracellular Calcium stores?How is calcium release triggered? How does it radiate over surface of
egg?Doing the Calcium wave… http://sdb.bio.purdue.edu/dbcinema/
Campbell fig 47.3
More about the slow block What does calcium release do?
Cortical granules fuse with PMRelease contents into perivitelline
space What are cortical granules?
Where are they located? What do they contain?
enzymes mucopolysacchariddes
More about the slow block
What do mucopolysaccharides do in perivitelline space?Remember osmosis? How do mucopolysaccharides affect
osmolarity?What does this do to perivitelline
space?
More about the slow block
What do the enzymes from cortical granules do?What happens when polysaccharides
become crosslinked?How would this affect sperm
penetration?
How long does all of this take?
What have we learned?
Preformation vs. Epigenesis Fertilization
Acrosome reactionFast block to polyspermySlow block to polyspermy (aka cortical
reaction)
Next day
Cleavage and Morphogenesis