Building a human Flashcards
What are the steps of embryonic developement
Fertilized egg
(clevage)
Blastocyte
(maturation of inner cell mass)
Mature blastocyte
(gastrulation)
Cleavage -> what it generates and what are the main two layers formed.
Inner cell mass: will later on form the embryo
Tropoblast: will connect with uterus
What 2 layers arise from maturated inner cell mass and what both are called together
Epiblast and Hypoblast, jointly called blastodisc.
Process of gastrulation -> what happens and what 3 layers are form
Cells from the epiblast migrate under and inwards, in between epiblast and hypoblast.
This forms 3 layers of cells: ectoderm, mesoderm and endoderm
What the endoderm, mesoderm and ectoderm will become.
Neurulation: what it is and how it happens. 2 ways folds join (extrinsic and intrinsic)
Formation of the neural tube. Works by infolding of the neural plate at primitive streak, creating neural folds that slowly come towards each other and connect.
Extrinsic: proliferation of cells
Intrinsic: neural tube contracts on itself
What is secondary neurulation
Formation of neural tube at lumbar and sacral regions by de novo formation of a lumen in neural tissue
Ancephaly, craniochisisis, spina bifida. What these are
Neural tube defects.
What the neural crest is and what they give rise to
Neural crest are embryonic cells that arise from the ectoderm layer. Make up peripheral and enteric nervous system, smooth mucle, cartilage…
What is formed by the mesoderm
What the notochord is useful for
It is a structure that follows down the entire vertebral column, and serve a central line for intervertebral disks (nucleus pulposus)
Describe somatitogenesis and how it shapes neural crest migration. Also 3 things somites become. Example of defect in somatitogeneis
Somites bud from the anterior of mesoderm as embry extends posteriorly. They differentiate into myotome, dermatome and sclerotome. Caudal side of somites inhibits passage of neural crest, so it is organised to rostral side, forming paravertebral ganglia. Defect example: scoliosis.
3 outcomes of the endoderm
Explain the concept of pattern formation
Patterns are generated early on a small scale, which the adult pattern arrises from.
What morphogens are and how their gradient can influence gene expression
Morphogens are proteins produced by cells at specific areas of the embryo. Their relative concentrations will cause different patterns of differentiation in different parts of the body.
Role of notochord in neural tube patterning
Serves are a central point from which things can grow. It is located ventrally of the neural tube, and it neurons next to it develope at motor neurons.
On dorsal side of neural tube, sensory neurons develop.
What sonic hedhog (Shh) is and what is its effect
Sonic hedghog is a protein primarily expressed in the notochord. It essentially causes differentiation of motor neurons at high concentrations and sensory neurons at low concentrations. In somites, it causes the differentiation into sclerotome.
