Development of PNS Flashcards
What weeks are considered the “critical period” of development where if something foes wrong odds are it happened during this window?
Weeks 3 to Week 8
What is the significance of the number of somites and the embryo?
You can use the number of somites to date the embryo
The sulcus limitans is made of the alar and basal plate. What do these two things contain?
Alar plate: contains sensory neurons
Basal plate: gives rise to motor structures like the brachial plexus
Fromation of the spinal cord is broken up into a central canal, sulcus limitans (alar and basal plate), and 3 zones. What are those zones and what future structres do they relate to?
Ventricular zone: closest to central canal
Intermediate zone: give rise to gray matter
Marginal zone: gives rise to white matter
The spinal cord comes from what germinal layer ?
Neural ectoderm
What zone of the forming spinal cord contains stem cells, gives rise to CSF, makes ependymoblasts?
Ventricular zone
Axons and oligodendrocytes are found in what zone of the forming spinal cord?
Marginal zone
What is found in the intermediate zone of the forming spinal cord?
Cell bodies such as glioblasts, astorcytes, neurons, radial glaial cells
What cells found in the marginal zone of the developing spinal cord actually migrate into the CNS and technically come from mesoderm ?
Mesenchymal Cells –> microglial cells
What is the location of the spinal cord in a new born compared to an adult?
New born: L2 or L3
Adult: L1 or L2
Formation of the dorsal and ventral region are dependent on concentration gradients.
What is at high concentration in the dorsal portion neer the roof plate?
What is at high concentration in the ventral portion by the floor plate?
High [] of BMP at roof plate
High [] of Shh at floor plate
What effect does high [] of BMP have in the formation of the spinal cord?
High [] of BMP is released from the dorsal portion (roof plate/epidermis) and activates Pax3 and Pax7. This release activates the differentiation of sensory neurons and alar plate
What affect foes High [] of SHH have on the formation of the spinal cord?
High [] of SHH at the floor plate (and from notochord) activates NKX2.2 and NKX 6.1. This activates the formation of ventral neuron and basal plate formation
Lower levels of SHH and higher levels of BMP just dorsal of the floor plate activate what two factors to create what structures?
NKX6.1 and PAX6 to form ventral motor neurons to make ventral horns
