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Flashcards in Embryology Deck (14)
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Primary Neurulation

1. induction of neuroectoderm of neural plate
2. elevatin form neural folds which come together and fuse
3. closure begins at cervical and moves rostrall and cadually
4. closes by 4th week


2ndary neurulation

1. caudal part of tube forms from prmitive streak remains condense to form medullary cord
2. mesenchymal to epithelium cell transformtion
3. canalization
-contribute to the sacral segments of CNS


Brain flexures - where

1. midbrain @ mesencephalon
2. cervical @ spinomedullary jnc
3. pontine posteriorly


Brain vesicles. describe development

5th week cranial end of neural tube forms vesicles- 3 1ary > 5 secondary.
Walls > brain and brain stem
Cavities > ventricles
Neural tube > spinal cord


Ascent of spinal cord

-vertebral column growth outstrips spinl cord growth = appear like cord ascends
-results in:
1. dissassosition bt vertebrae and cord segments
2. cauda equina forms


PNS development
-destinations of neural crest cells?

from neural tube (basal plates) and neural crest cells (sensory neurons of DRG, CN ganglia, postgang NS ganglia, enteric ganglia)


Tissues of neural tube

neuroectoderm (1ry) mesoderm of primitive streak (2ndary)


type of epi of neuroectoderm

pseduostrt columnr


risk factors for neural tube defects

-anticonvulsant drugs
GIVE folic acid as prevention during preg



rostral neural tube opening



-sensory issues below lesion
-hydrocephalis (water in brain - lemon sign of collapsed frontal bone, banana sign for pushed cerebellum)


How are brain cells developed (histogenesis?)

1. neuron daugher cells from tube migrate to outer wall = INTERMEDIATE ZONE >> grey matter: neurons, glial cells
2. internal layer to intermediate = VENTRICULAR ZONE >> ependymal cells - line ventricles and canal
3. periphery: axons from intermediate zone = MARGINAL ZONE >> white matter


what are basal plates (floor plate)

neuroblast accumulate in ventral intermediate zone > LMN and pregang ANS neurons in ventral and later horn of spinal cord


what are alar plates (roof plate)

neuroblast accumulate in dorsal intermedite zone > interneurons of dorsal horns for sensory pathway