Gastrulation and Neurulation Flashcards
What is gastrulation?
Formation of third layer
When does elongation occur?
16 days
Explain gastrulation
Epiblasts divide in the primitive streak and migrate along it, accumulating in the space between the epiblasts and the hypoblasts forming the mesoderm. It then replaces hypoblasts cells to form the endoderm.
How is the dorsal ventral axis formed?
Skin is formed from signals from bone morphogenic proteins (BMP). Neural development occurs from the release of notocord factors choradin, noggin and follistatin that block BMP
Explain the formation of the neural tube
Induced by notocord. Cells on the edge of the neural plate form folds and a groove. The apex of the ectodermal cells become constricted forming a curve. The edges roll over to form a tunnel. Rostal neuropore closed day 25, caudal neuropore closed day 27
What is the ectoderm derived from?
The epiblast layer of cells
What is the mesoderm derived from?
The epiblast cells that enter the space between the ectoderm and the hypoblasts
What is the endoderm derived from?
Replacement of hypoblast cells by migratory epiblasts from primitive streak
Derivatives of ectoderm
Epidermis lens and retina Olfactory epithelium Oral cavity epithelium Sensory organs of the ear Glands: salivary, sweat and mammary
Derivatives of mesoderm
Paraxial mesoderm: Somite –> sclerotome, myotome, dermatome
Intermediate mesoderm: kidneys and gonads
Lateral mesoderm: Somatic and splanchnic –> cardiovascular
Midline mesoderm: Notocord, nucleus pulposus, invertebral disc
Derivatives of endoderm
Buds come out of the gut tube to form internal organs such as the pancreas and the liver
What is neural crest cells derived from?
The neural plate
What are the types of derivatives of neural crest cells?
Neurons and glia Cartilage and bone Connective tissue Pigment cells Sensory neurons and glia Sympathoadrenal cells
