Repro facts Flashcards
Where is the ZPA? What does the ZPA produce?
- base of limb buds
- Shh (anteropost axis and CNS devo => holoprosenceph)
Where is the AER and what does it produce?
- tip of limb bud
- Wnt-7 (dorsal-ventral axis)
- FGF-gene (mitosis of underlying mesoderm to lengthen limb)
What are Hox/homebox genes?
- segmental organization
- craniocaudal
- genes that code for transcription factors
Hox mutations causes:
appendages in wrong locations
When does the blastocyst stick (implant)?
day 6
When does the NT close?
week 4
When does the heart begin to beat and limb buds begin to form?
week 4 (4 limbs, 4 heart chambers)
When does fetal movement start?
week 8
When does genitalia differ from male/female?
week 10
How many layers at wk 2?
2
How many layers at wk 3?
3
Where does the notochord come from?
mesoderm
Monochorionic (1 placenta) diamniotic (2 amnions) twins happen at:
4-8 days
Aplasia v Agenesis
Aplasia: absent organ despite presence of primordial tissue
Disruption
secondary breakdown of previously normal tissue
Deformation
Extrinsic disruption (after embryonic period)
Malformation
intrinsic disruption (during embryonic period)
Sequence
abnormalities result from a single primary embryologic even (oligohydramnios to Potter’s sequence)
Placenta: fetal components
cytotrophoblasts (inner layer of chorionic villi)
syncytiotrophoblast (outer layer; makes hCG to stim corpus luteum to secrete progest during 1st trimester; no MHC-1)
Placenta: maternal component
decidua basalis (derived from endometrium, maternal blood in lacunae
Urachus vs Vitelline duct
Urachus/allantois- to the urine (bladder)
Vitelline- to the midgut (Meckel diverticulum)
Note: both go to the umbilicus
