Embryology Flashcards
Produced at base of limbs in zone of polarizing activity.Involved in patterning along anterior-posterior axis. CNS development; mutationi = holoprosencephaly
Sonic Hedgehog Gene
Produced at apical ectodermal ridge (end of developing limb); Necessary for proper organization along dorsal-ventral axis
Wnt-7 gene
Produced at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, lengthening of limbs
FGF gene
Involved in segmental organization of embyro in a craniocaudal direction.
Homeobox genes
Mutation of this causes appendages in wrong locations
Hox gene
Day 0
fertilization
Day 2
zygote in fallopian tube
Day 3
Morula
Day 5
Blastocyst
Day 7-10
Implantation; when hCG secretion begins
2 weeks
Bilaminar disc; epiblast & hypoblast
3 weeks
Trilaminar disc; Gastrulation
Primitive streak, notochord, mesoderm and its organization, and neural plate begin to form
Embryonic period
3-8 weeks; neural tube forms by neuroectoderm and closes by week 4; organogenesis; extremely susceptible to teratogens
Week 4
heart begins to beat; upper and lower limb buds begin to form (4weeks; 4 limbs)
Week 5
Fetal cardiac activity visible by transvaginal ultrasound
Week 10
Genitalia have male/female characteristics
Process that forms the trilaminar embryonic disc. Establishes the ectoderm, mesoderm and endoderm. Starts with epiblast invaginating to form primitive streak
Gastrulation
Adenohypophysis (from Rathke pouch)
Surface ectoderm