embryogenesis 4 Flashcards
what is somitogenesis
process by which the stomites are formed
what is a somite
Earliest visible structure is the somites, this is a clump of cells which differentiate into tissue.
what are stem cells
the building block of all of the embryo and its tissue. They can produce identical copies of themselves indefinitely. They become committed cells which have differentiated.
pluripotent stem cell then turn into what and how
turns into a commited stem cell through liniage comitment
commited stem cell then turn into what and how
progenitor cell through specification
Progenitor cell then turn into what and how
Differentiated cells through differentation.
the embryonic stem cell will undergo lineage commitment into three types of cell layers, what are they
Mesoderm, Endoderm, Ectoderm
the somite is made from how many cell types?
4
the somite is derived from…
condensation of paraxial mesoderm.
what are the four cell types that make up the mature somite and what they form
Sclerotome – vertebrae and rib cartilage
Myotome – musculature of back ribs and limbs
Dermatome – dermis of the back
Syndetome – tendons and blood vessels
what do the mesoderm cells form
Cardiac, skeletal and smooth muscle
tubule cell of kidney
Red blood cells
what will the endoderm cells form
lung cells, thyroid cells, pancreatic cells
what will the ectoderm cells form
skin cells, neuron cells and pingment cells
describe the location of developing somites
As the neural folds are rising into apposition, pairs of somites are forming on either side of the neural tube.
Connective tissue/ bone arises from where
paraxial (stomitic) mesoderm
describe the epithelium of the somites
the epithelial cells form the clumps that are visible, that is what we describe as the somite
describe how somite begin to develop
Somites start as condensations of mesenchymal cells.
After separation, expression of fibronectin and N-cadherin organises
‘inner’ mesenchymal and ‘epithelial’ components form
Within the mature somite there are how many types of possible muscle precursor cells
3
Within the mature somite there are three types of possible muscle precursor cells
Primaxial myoblasts
Abaxial myoblasts
Future satellite cells
how are muscle generated (overveiw)
Muscle are generated from simple cells, then into myoblasts than cells align, then into myotube, and into myofibers
to form the skeltal system the ______ must form first
cartilage and tendons
there are two type of osterogenesis (skeltal formation) what are they
Intramembranous - formed between two membranes
Endochondral - cartilage turned to bone
descibe in deatail to formation of bone (endochondral)
Mesenchymal cells commit to becoming cartilage
Committed mesenchymal cells condense into nodules and differentiate into chondrocytes
Chondrocytes proliferate and create cartilage model of the bone.
Chondrocytes stop proliferating and increase their cellular volume.
Enlarged chondrocytes alter secretion of ECM to enable calcification by calcium Phosphate.
Hypertrophic chondrocytes die, surrounding cells differentiate into osteoblasts. Blood vessels invading the bone bring in osteoblasts and chondroclasts which remove dead cell
what bones are formed in the lateral plate mesoderm
limb skeleton
