Nervous System Development Flashcards
Which germ layer gives rise to the nervous system?
Ectoderm (outermost layer)
What is the notochord?
A cord of cells that similar to cartilage that gives the embryo its longitudinal axis - develops in the mesoderm. It sends signals for correct development - neural induction
What is the neural plate?
Part of the ectoderm which gives rise to the nervous system
Describe how the neural plate changes to become the nervous system
The plate begins to curl up at the sides, forming a neural groove. The neural folds are the walls of this groove. The neural folds fuse together to form the neural tube. The ectoderm that is pinched off when the neural folds fume is the neural crest, and it becomes the PNS. This is called neurulation
How do the somatic motor nerves develop?
All neurons with their soma in the PNS derive from the CNS. The neural crest develops in association with the underlying mesoderm. The mesoderm forms bulges either side of the neural tube - somites. These give rise to 33 individual vertebrae of the spinal cord and related skeletal muscles. The nerves innervating these muscles are called somatic motor nerves
What is “the organiser” region in the embryo?
The embryonic region that gives rise to the notochord and is responsible for fixing the cells destiny to become neurons. If the early organiser cells from the back of an embryo are transplanted into the belly of another, you get conjoined twins with 2 notochords
Explain how developing neural cells communicate with surrounding tissue
Sonic hedgehog protein is secreted from the notochord and floor plate while BMP is secreted by roof plate. The gradient of these molecules signals the dorso-ventral pattern of the embryo. Retinoic acid, Wnt, and FGF are responsible for the antero-posterior pattern. They activate TFs that regulate developing cell morphology and behaviour.
What is the role of Hox genes?
They determine the segmented pattern of the spinal chord by being activated at specific times. Theyre highly conserved and their expression is tightly spacially and temporally regulated.
What is neural differentiation?
When structures become more complex and specialised in their function during development
What are primary vesicles?
They develop at the rostral end of the neural tube and signify the first step in the differentiation of the brain.
Name the different primary vesicles
Prosencephalon - forebrain. Mesencephalon - midbrain. Rhombencephalon - hindbrain. Connects with caudal neural tube (becomes spinal cord).
