Download Development of NS_20..

Department of Histology and Embryology, P. J. Šafárik University, Medical
Faculty, Košice
Development of nervous system : Sylabus for foreign students
Author: Prof. MUDr. Eva Mechírová, CSc.
Development of notochord and notochordal process
- by proliferation of epiblast (ectodermal) cells primitive streak develops
- primitive streak grows cranially in the midline of the bilaminar embryonic
disc, elongates and its cranial end proliferates to form the primitive node
- in the primitive streak develops a narrow primitive groove that ends in a
primitive pit
- influence of embryonic growth factors – epiblastic (ectodermal) cells
proliferate and migrate through the primitive groove between epiblast and
hypoblast, spred cranially and laterally and give rise to embryonic mesoderm
- from the cells of primitive node the notochordal process and later
notochordal canal is developed – situated in the midline between ecto and
endoderm
-ventral wall of notochordal canal disappears and gives rise to a solid cord of
cells – the notochord
3rd week- the developing notochord induces the overlying ectoderm to
produce the neural plate – situated between primitive node and
oropharyngeal membrane
Formation of neural tube
19th day
Development of brain vesicles
Histogenesis of neural tube and neural crest
Development of spinal cord and histogenesis
● growing and thickening of neuroepithelium of neural tube, formation of
canalis centralis
● lateral walls produce a groove - sulcus limitans that divides
horizontally the spinal cord in:
(A) Ventral part → basal plate → neuroblasts - motor neurons
(B) Dorsal part → alar plate → neuroblasts - sensory neurons
dorsal wall – roof plate and ventral wall – floor plate
-
as the basal plates grow and enlarge, produce ventral median fissure
as the alar plates grow and enlarge, produce dorsal septum and
dorsal median sulcus
Spinal cord development
Development of rhombencephalon – hindbrain
- the pontine flexure divides hindbrain into metencephalon and
myelencephalon
Metencephalon
- becomes the cerebellum - from the dorsal part of alar plate =
cortex cerebelli, nuclei – pontine, cochlear, vestibular, of trigeminal
nerve
- nerve fibers connecting cortex cerebri and cerebelli in the ventral
region form pons Varoli
Myelencephalon
- from the 5th brain vesicle- myelencephalon - gives rise the
medulla oblongata and dorsal part of the IV. brain ventricle
- neuroblasts of alar plate migrate into marginal zone and form
gracile and cuneate nuclei laterally
- ventrally are situated the pyramids - tractus corticospinalis
- neuroblasts of basal plate develop into motor neurons of nuclei of
cranial nerves
- lateral walls together with basal and alar plates rotate around
longitudinal axis of floor plate (like opening a book) and the roof
plate become thiner