Germ layer
cell lineage specification
allocation of stem cells into lineages that have a more restricted and less plasticity in developmental potential. the ability of the cell to undergo self renewal becomes limited as cell becomes more restricted
hypoblast
cell contribute to placenta and support the embryo
differentiation
cells will develop from an uncommitted stem cell type to a differentiated cell with specific functions
plasticity
develomental versatility of cell to form other structures. Influenced by cell signal and adult Stem cells are less plastic thatn embryonic stem cells
three germ layers
ectoderm - layer of cell in contact with the outside world mesoderm - bone, cartilage, connective tissue of body, skeletal muscle, smooth muscle, cardiovascular, genitourinary endoderm - internal lining of hollow organs like stomach, lung, bladder
two cell layers in embryo
epiblast and hypoblast
two main outcomes from gastrulation
establishment of body axes and formation of three germ layers by the end of third week
what is germ layer
layer of cells which may differentiate into any cell in adult body
gastrulation
migration of epiblast cells through the primitive streak
migration
movement of cells based on interactions with surrounding cells and environment. Interactions is juxtacrine. E.g: mature ooccyte migrates as it becomes the embryo
Induction
one cell tissue acts on another cell tissue to alter its developmental outcome. Eg: cellular pure pressure = inductive response. Teeth formation
Development of an embryo in2 weeks
the embryo or inner cell mass has differentiated into two layers and the amniotic cavity has developed
prochordal plate
thickening of cell
Lineage specification and differentiation
totipotent, pluripotent, multipotent, restricted cell lineage, committed cell type differentiated or mature functional cell
Four division of mesoderm
axial or notochord, paraxial, intermediate and later plate
epiblast
cell that give rise to three main tissues layers of the embryo cells that have the most control because it forms all the cells of the embryo the epiblast is above the hypoblast.
route of epiblast migration
1. ventrally to form endoderm 2. through streak and move cranial but stay in the middle to form axial mesoderm or notochord. Notochord is important because it induces formation of brain and spinal chord 3. through streak and laterally to form middle layer called mesoderm 4. remain on dorsal outer surface to form ectoderm