Ovaries & Testes, Sperm & Egg (and their reproduction), and Fertilization/Early Development
AP Biology 2005-2006 Fertilization. AP Biology 2005-2006 Fertilization Joining of sperm & egg ...
Transcript of AP Biology 2005-2006 Fertilization. AP Biology 2005-2006 Fertilization Joining of sperm & egg ...
AP Biology 2005-2006
Fertilization
AP Biology 2005-2006
Fertilization Joining of sperm & egg
sperm head enters egg
AP Biology 2005-2006
Cleavage Repeated mitotic divisions of zygote
1st step to becoming multicellular unequal divisions establishes body plan
different cells receive different portions of egg cytoplasm & therefore different regulatory signals
AP Biology 2005-2006
Cleavage zygote morula blastula
establishes future development
AP Biology 2005-2006
OrganogenesisUmbilical blood vessels
Chorion
Amnion
Yolksac
AllantoisFetal blood vessels
Maternal blood vessels
Bird embryo
Mammalian embryo
Placenta
AP Biology 2005-2006
Placenta Materials exchange across membranes
AP Biology 2005-2006
Human fetal development
7 weeks4 weeks
AP Biology 2005-2006
Sex determination
XY
XX
TestesY
Sperm Zygote
Zygote
Ovum
Sperm
Ovum
X
X
X
Indifferentgonads
SRY
No SRYOvaries
(Follicles do notdevelop until
third trimester)
Seminiferoustubules
Develop inearly
embryo
Leydig cells
AP Biology 2005-2006
Human fetal development10 weeks
AP Biology 2005-2006
Human fetal development
12 weeks 20 weeks
AP Biology 2005-2006
Human fetal development The fetus just spends much of the 2nd & 3rd
trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid
Week 20
AP Biology 2005-2006
Human fetal development24 weeks (6 months; 2nd trimester)
fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix
AP Biology 2005-2006
Human fetal development30 weeks (7.5 months)
umbilical cord
AP Biology 2005-2006
Getting crowded in there!!32 weeks (8 months)
The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming
AP Biology 2005-2006
Birth
Hormone induction
positive feedback
AP Biology 2005-2006
Intestine
Placenta
Umbilicalcord
Wall ofuterus
VaginaCervix
Birth (after 36 weeks)
Bladder
AP Biology 2005-2006
The end of the journey!