Week 1 Oral Facial Development and Abnormalities Flashcards
what are the 3 stages of human development and how long are each
proliferation period (0-3 weeks)
embryonic period (3-8 weeks)
fetal development period (9 weeks to term)
what happens in the proliferation period
-fertilization of ovum yields zygote
-mitotic cleavage of zygote forms blastomeres
-more than 32 blastomeres becomes a morula
-keeps dividing then is referred to as a blastocyst
-then travels down uterus and attaches to wall and is called an embryoblast
-inner cell mass of the embryoblast becomes bilaminar embryonic disc
-outer cell mass becomes the cytotrophoblast and syntrophoblast
what is a cyst
any mass that is lined with a cells and is hollow inside
when does implantation of the embryoblast in the uterine wall begin and complet
begins at day 4 and is complete at day 10
what layers are precursors to the placenta
cytotrophoblast and syntrophoblast
what are the layers of the bilaminar embryonic disc
epiblast and hypoblast
what makes up the epiblast layer
ectoderm and mesoderm
what makes up the hypoblast layer
endoderm
what are the structures associated with the bilaminar embryonic disc
epiblast layer
hypoblast layer
amniotic cavity
blastocyst cavity
syntrophoblasts
cytotrophoblasts
what forms Heuser’s membrane
enlargement of the amniotic cavity and migration of cells out of the hypoblast
what does Heusers membrane form
the internal lining of the blastocyst cavity now called the yolk sac
what are the cell layers in the proliferation period
epiblast, embryonic mesoderm, hypoblast
what are the embryonic cavities in the proliferation period
amniotic
yolk sac
chorionic
during the 3rd week of development, the bilaminar embryonic disc is characterized by the formation of what
-primitive streak
-notochord
-neural tube
what are the three distinct emrbyonic germ layers during the 3rd week of development
ectoderm, mesoderm, and endoderm
what does the ectoderm develop from
the epiblast layer
what does the endoderm develop from
hypoblast layer
what are the 3 features of the primitive streak
pit, node, and groove
what does the primitive node turn into
notochordal process -> notochord
how do pre-notochordal cells form the notochord
the cells invaginate within the primitive node and migrate towards the cephalad until they reach the prechordal plate. they then detach themselves from the ectodermal layer to line within the mesoderm forming the notochord
what does the notochord do
- functions as a primitive skeletal support of the embryo around which the axial skeleton later forms
- induces formation of somites, the precursor of the vertebral column, ribs, associated back muscles and the overlying dermis
what layer does the notochord form from
the ectoderm
what are the different parts of mesoderm
-paraxial mesoderm
-intermediate mesoderm
-lateral plate mesoderm
what are the 2 parts of the lateral plate mesoderm
visceral and parietal
what does the paraxial mesoderm form
somites
what does the intermediate mesoderm form
urogenital system