Embryology Flashcards
what is a functional disorder?
looks ok, doesn’t work well
frequency of birth defect?
1:33 (live births only)
what is the most common birth defect? frequency?
heart defect 1:200
what is the second most common birth defect? frequency?
hypospadias male only
1:300
how many cells is a morula?
16
whats the diference between a blastocyst and blastocoele?
blastocoele has a cavity
blastocyst has two types of cells?
outer trophoblast
inner cell mass
What does the trophoblast form?
placenta
extraembryonic structures
when does the blastocyst implant?
between 5-10 days
inner cell mass splits to?
epiblast
hypoblast
epiblast of hypoblast becomes the embryo?
epiblast
what is gastrulation, where does it form?
epiblast’s formation of the 3 germ layers
what layer does the lungs come from?
endoderm
what layer does the heart come from?
mesoderm
what layer does the pancreas/liver come from?
endoderm
T/F? notochord comes from ectoderm?
Nope. mesoderm
what’s the purpose of notochord?
induces ectoderm above it to form neural plate
What forms neural crest?
cells at top of neural tube
are the neural tube cells mobile?
yes, migrate away from wide range of structures
melanocytes and dentine come from which tissue?
neural crest derivative
most of the face comes from mesoderm?
Nope. neural crest
example of neural crest defect?
cleft palate
dermis comes from which germ layer?
mesoderm
pleura peritoneum pericardium comes from which germ layer?
mesoderm
whats the opposite of epithelial?
mesenchymal
What is mesenchyme?
loose freely moving with Ct inbetween cells
urogenital tract comes from which germ layer??
mesoderm
3 areas of mesoderm?
paraxial (medial)
intermediate
lateral
paraxial mesoderm forms what 3 things?
dermis of skin
axial skeleton
limb muscles
intermediate mesoderm forms?
urogenital system
lateral mesoderm forms?
heart
wall of gut/respiratory tissues
what are somites? which germ layer do they come from?
mesoderm
swellings down paraxial mesoderm
what is a somitomere?
pro-somite
which pair do semitomere becomes independent somite?
8th pair
somite splits into 2 things?
sclerotome (axial skeleton)
dermomyotome
dermomyotome splits into?
dermatome
myotome
where does the axial skeleton come from? vs. appendicular skeleton?
aial: sclerotome
appendicular: lateral plate
human ‘gills’ are called?
pharyngeal arches
pharyngeal arches become?
jaw, face, ear, throat structures and glands
when do limbs grow? what layer initates them?
end of 4 week
initiated by mesoderm
limb field is what?
patch of mesoderm to make a free limb
if remove whole patch vs. part of it?
whole=no limb
part of patch = compensation
transplant free limb patch?
ectopic limb
How thick is the ectoderm overlying limb bud? why is it significant?
one cell thick
easy to damage or split resulting in diplopodia or other defects
how are digits developed?
hands and feet start as discs, sculpted by apoptosis
what is syndactyly?
fused fingers
what is the most common congenital limb abnormality? frequency?
congenital hip dislocation due to malformed acetabulum
1:500
What is amelia? meromelia? caused by?
absent or reduced limbs. Thalidomide
what forms the epithelial lining of liver, pancreas?
ENDODERM!
What is the Coelom?
holds the viscera
Where does coelom come from?
split in lateral mesoderm
what does the lateral mesoderm divide into? what do the two become?
splanchnic mesoderm: viscera
somatic mesoderm: muscle
describe the folding formation of the coelom?
pulls toether like a bag pull string in 3D
Where does the lumen of gut come from?
pinched off from the yolk sac during the coelom folding (tube within a tube)
what is the stomodeum?
proctodeum?
membrane covering future mouth and anus
ectoderm meets endoderm when what happens to the oral plate?
when it breaks = oral cavity
what is the cloacal membrane?
anus seal where ectoderm and endoderm meet
What is the allantois?
in body stalk, used to be nitrogenous waste storage in animals
what is between allantois and hind gut? what does it do?
urorectal septum that divides rectum from urogenital tract
what gives rise to bladder and urogenital tract?
allantois
how many pharyngeal pouches form?
4
where does most of the heart come from?
lateral splanchnic mesoderm
how is the heart developed?
from two endocardial tubes fused together
how do you get 4 chambers of heart in embryo?
folding of two fused tube
where does heart muscle comes from? germ layer.
mesoderm
what’s the most common congenital heart defect?
ventricular septal defects
congenital heart defect issue in utero?
Nope. usually immediately post birth
does the foramen ovale allow left to righ flow of blood?
No. it shouldn’t
Foregut supplied by?
coeliac artery
midgut supplied by?
superior mesenteric
hindgut supplied by?
inferior mesenteric
describe GIT growth pattern.
lengthens>haipin rotate around axis>elongation>more folding>herniation of GIT
When does herniaion of GIT happen?
week 6-7
When does GIT retract back into cavity?
week 9
What is omphalocele?
no retraction of herniation of GIT
retraction but failure to seal wall is?
umbilical hernia
frequency of omphalocoele?
1:25 000
viscera comes from which germ layers?
initially endoderm which interacts with mesoderm
Situs invertus frequency?
1: 10 000
What determines left and right in blastocyst?
via primitive groove and cilia that generate right to left current
If cilia in primitive node don’t work, are you guaranteed to get situs invertus?
Nope 50/50 change
intermediate mesoderm forms what system?
urogenital system
genital or urinary system forms first?
urinary
what are the 3 kinds of kidneys that develop?
pronephros
mesonephros
metanephros
kidney from which germ layer?
mesoderm
what happens to mesonephric duct in males?
reused and attaches to testes to become the vas deferens
kidneys migrate from where to where?
inferior to superior
ureters start off where?
mesonephros at bladder
penis forms by fusion of?
urogenital folds
what happens when urogenital folds don’t fuse completely?
hypospadiasis: urethra at base of penis
all major organogenesis complete by?
3 months: first trimester
