9. Intro to Embryology Flashcards
Neurulation
A = 18 days
B = 20 days
Neurulation
C = 22 days
D = 23 days
What % of babies are born with a significant developmental defect detectable at birth?
2.4%
Blastocyst
5 day pre-embryo
Implantation
The conceptus actively invades the lining of the uterus
8 days after fertilisation it has sunk completely beneath the surface
Pre-embryo
0-2.5 weeks after fertilisation
Embryo
2.5-8 weeks after fertilisation
Fetus
9 weeks after fertilisation till birth
Length of pregnancy
= time since last menstrual period
= time after fertilisation + 2 weeks
Highly regulative stage of development (e.g. twins can form)
Pre-embryo
Highly sensitive stage of development - major morphological abnormalities
Embryo
Sensitive stage of development - tissue maturation at risk, and influences on later adult life
Fetus
Gastrulation
About 14 days after fertilisation
Formation of main body axis
Moment of individualisation
The ‘middle layer’ – mesoderm – arises from the ectoderm
