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PREGNANCY & HUMAN DEVELOPMENT (PLACENTATION (Placenta = "flat…
PREGNANCY & HUMAN DEVELOPMENT
FERTILIZATION
Ejaculated sperm not ready for fertilized
Capacitation (spermatozoan maturation) <-> spermatozoa to oocyte
Acrosome reaction (allows spermatozoa penetrate zona pellucida -> fuse w/ oocyte membrane)
Need high sperm # for zona production
Polyspermy not allowed (does not allow egg fertilization w/ >1 sperm)
Controls Chromsome #
Completion of Meiosis II
IMPLANTATION
Occurs 6-7 days post-ovulation
Trophoblast ("to feed") proliferation; provide nutrients -> embryo
Cytotrophoblast (cellular trophoblast)
Syncytiotrophoblast ("together; of cells; nutrition; bud"). Which substances cross placent (nutrients, O2) and don't (toxins, hormones)
Implantation ~ 1 week
Human chorionic gonadotropin maintains corpus luteum
Reproduction is inefficien
t
~60% zygotes fail to implement
30% of all implantations -> miscarriage (aneuploidy - abnormal chr # or due to miscarriage)
PLACENTATION
Placenta = "flat cake"
Acts as filtration system
Connects developing fetus to uterine wall (nutrient uptake, thermoregulation, waste elimination, gas exchange <-> via mother's blood supply)
Fights against infection
Hormone production -> supports pregnancy
EMBRYONIC & FETAL TETRATOGENS
TETRATOGEN:
Agents produces fetus abnormalities
Environmental
Infectious Agents
Heavy Metals
Social
Alcohol
Amphetamines
Medical
Antibiotics
Anti-coagulants
ACE Inhibitors
Anticonvulsants