Sonic hedgehog gene
Wnt-7 gene
FGF gene
- Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs
Homeobox (Hox) genes
Within week 1
Within week 2
- 2 weeks = 2 layers
Weeks 3-8
Week 4
Week 6
Fetal cardiac activity visible by transvaginal ultrasound
Week 8
- “Gait at week 8”
Week 10
Genitalia have male/female characteristics
Surface ectoderm
Neuroectoderm
“Neuroectoderm - think CNS”
Neural crest
Mesoderm
Mesodermal defects = VACTERL
Endoderm
Deformation vs malformation
DEFORMATION: extrinsic disruption; occurs after embryonic period
MALFORMATION: intrinsic disruption; occurs during embryonic period (weeks 3-8)
ACE inhibitors
Renal damage
Alkylating agents
Absence of digits, multiple anomalies
Aminoglycosides
Ototoxicity
Antiepileptic drugs
Diethylstibestrol
- Congenital Mullerian anomalies
Folate antagonists
- Includes trimethroprim, methotrexate, antiepileptic drugs
Isotretinoin
- Contraception mandatory