5. Differentiation of the neural tube and the brain vesicles Flashcards
General description of neurulation
Formation of the primordia of the nervous system including
(1) isolation of the neuroectoderm
(2) formation of the neural plate and its transformation into neural tube
(3) the appearance and early development of the neural crest and ectodermal placods.
General description of neurulation
Formation of the primordia of the nervous system including
(1) isolation of the neuroectoderm
(2) formation of the neural plate and its transformation into neural tube
(3) the appearance and early development of the neural crest and ectodermal placods.
What does neuroectoderm include?
- Neural plate
- Neural crest
- Ectodermal placods
Derivatives of surface ectoderm
epithelium and appendages of the skin (hair, nail, sebaceous and sweat glands), epithelia of the breast, epithelium of the cornea and conjuctiva
epithelium and appendages of the stomodeum and the cloaca – epithelium and glands of the nasal and oral cavity, epithelium of the lacrimal apparatus, enamel of teeth, epithelium and glands of the anus, epithelium and glands of the distal male uretra
What does neural plate transform or differentiate into?
Transforms into the neural tube.
=> Its rostral end gives the brain, while the remaining elongated part differenciates into the spinal cord.
4 things that the neural crest give rise to?
- Peripheral nervous system
- Ectomesenchyme
- Melanocytes
- Aorticopulmonary septum of the heart
What does ectomensenchyme differentiate into?
- Connective tissues
- Cartilages and bones of the skull
- Dermis of face and neck
- Smooth muscle cells of the vessels of the face and forebrain
- Odontoblasts of the teeth !!!!
- Meninges
What are the 6 types of placodes?
- Olfactory placode
- Lens placode
- Otic placode
- Epibranchial placode
- Hypophysis placode
- Trigeminal placode
What does olfactory placode differentiate into?
primary neuroepithelial cells of the olfactory area of the nasal cavity.
What does lens placode differentiate into?
lens of the eyeball.
What does otic placode differentiate into?
epithelia (including the secondary neuroepithelial hair cells) of the inner ear, neurons and glial elements of the spiral and vestibular ganglia.
What does Epibranchial placode differentiate into?
secondary neuroepithelial cells of the taste buds, viscerosensory ganglia of the CN VII, IX and X.
What does Hypophysis placode differentiate into?
adenohypophysis (anterior lobe of the pituitary gland).
What does Trigeminal placode differentiate into?
neurons and satellite cells of the trigeminal ganglion.
How does Formation of the neural tube occur?
How do Primary and secondary neurulation occur together?
A mass of mesenchyme (caudal eminence) condenses, hollows out (=lumen develops) and then joins with the neural tube formed by primary neurulation.
-> Secondary neurulation forms the sacral and coccygeal spinal segments.
Differentiation of the neural tube
-> What happens during rostrocaudal differentiation?
at the rostral end the brain, caudally the spinal cord develops
Differentiation of the neural tube
-> What happens during dorsoventral differentiation?
dorsal neuronal networks receive sensory input from the periphery, while ventral neurons give the motor output of the CNS
Differentiation of the neural tube
-> What happens during radial differentiation?
thickening of the wall of the neural tube, appearance of new cells including neurons and glial cells.
Rostrocaudal differentiation
-> At the rostral end of the neural tube three primary brain vesicles appear
-> What are they?
prosencephalon, mesencephalon, rhombencephalon.
Rostrocaudal differentiation
-> To fill the space provided by the developing skull, 2 flexures which are ___ will appear
the cephalic and cervical flexures appear.
Prosencephalon divides into the ____ (3)
diencephalon and the paired telencepalic vesicles
Prosencephalon divides into the diencephalon and the paired telencepalic vesicles, while the rostral and caudal portions of rhombencephalon differentiates into ___ (2)
metencephalon and myelencephalon.
How many secondary brain vesicles?
5
____ appears as the third curvature of the brain.
Pontine flexure
What are Neuromeres?
segments of the developing brain
What are the 3 types of neuromeres?
rhombomeres, mesomeres, prosomeres
