Summary of Embryology Flashcards
Intersex Phenotypes
Complete Androgen Insensitivity Syndrome
Guevadoces
Non-Vitruvian conditions from defective growth
Achondroplasia- genetic disorder leading to dwarfism, reduced cartilage production
Phocomelia- congenital skeletal disorder as inhibited vascular growth in limb development (thalidomide)
Condition resulting from incomplete fusion of neural tube/ plates
Cleft palate- secondary palate connection to nasal cavity
Spinal bifida- failure of ectoderm to close/ spine
Anencephaly- failure of ectoderm to close/ brain
Fetus-in-fetu- closure of neural tube envelops and draws in twin/ ventral closure in abdomen
Conditions resulting from complications in primitive streak formation
Conjoined twinning- two primitive streaks leads to two babies and no separation by membrane
Axis duplication- primitive streak splits towards two head regions
Monozygotic complications
Foetal transfusion syndrome- inner cell mass splits, twins share trophectoderm layer therefore placenta, one smaller than other due to imbalance of nutrients
Cleavage
Mitosis with no net growth within the zona pellucida
Compaction
Cells switch on an adhesion molecule and clump together hard
Blastula formation
Internal geometric differences lead to trophectoderm, inner cell mass, epiblast, amniotic cavity, yolk sac and hypoblast
Implantation
Trophoblast of hatched blastocyst invades uterine epithelium
Gastrulation
Endoderm layer ‘pulled out’ due to restriction of yolk sac
Neurulation
Neural tube develops from invagination of ectoderm driven by local cell shape changes, ectoderm closes behind neural tube
Organogenesis
Mesoderm divides into somites by clock-and-wavefront mechanism, internal patterning by SHH signal via notochord, internal migration of neural crest cells/ primordial germ cells
