differentiation of ectoderm

theoretical exam dev bio lab

central nervous system

forms the neural tube

neurulation

formation of neural tube

primary neurulation

cell surrounding the neural plate direct the cells to proliferate, invaginate and pinch off the surface to form hollow tube

secondary neurulation

neural tube arises from a solid cord of cells and will sink to the embryo and will cavitate to form hollow tube

primary neurulation

initial epithelium, columnarization, rolling/folding, closure, neural tube complete

secondary neurulation

dispersed mesenchyme, mesenchymal condensation, medullary cord, epithelial transition/cavitation, complete neural tube

fishes

exclusively secondary neurulation

birds

the anterior portion of the neural tube is made by primary neurulation whereas the posterior part caudal to the 27th somite pairs is made by secondary neurulation

amphibians

mostly, neural tube is made by primary neurulation but the tail neural tube is made by the secondary neurulation

mammals

both primary and secondary neurulation happens but the secondary neurulation begins at the 35th somite pair

differentiation of the neural tube

gross anatomical level, tissue level, cellular level

gross anatomical level

the neural tube and the lumen bulge and constrict to form the chambers of the brain and spinal cord

tissue level

the cell populations within the wall of the neural tube will rearrange into different functional regions of brain and spinal cord

cellular level

neuroepithelial cells will differentiate into various types of neurons and glia present in the body

neurons

nerve cells

glia

supportive cells

3 primary vesicles

forebrain-prosencephalon, midbrain-mesencephalon, hindbrain-rhombencephalon

five secondary vesicles

prosencephalon = telencephalon and diencephalon
mesencephalon = mesencephalon
rhombencephalon = metencephalon and myelencephalon

adult derivatives and function of telencephalon

olfactory lobe - smell
hippocampus - memory storage
cerebrum - association (intelligence)

adult derivatives and function of diencephalon

optic vesicle - vision
epithalamus - pineal gland
thalamus - relay center of auditory and optic neurons
hypothalamus - sleep, temperature, and breathing regulation

adult derivatives and function of mesencephalon

midbrain - fiber tract between anterior and posterior brain, optic lobes, and tectum

adult derivatives and function of metencephalon

cerebellum - coordination complex of muscular movements
pons - fiber tracts between cerebellum and cerebrum

adult derivatives of myelencephalon

medulla - reflex center of involuntary movements

olfactory lobe

smell

hippocampus

memory storage

cerebrum

association

optic vesicle

vision (retina)

epithalamus

pineal gland

thalamus

relay center for optic and auditory neurons

hypothalamus

sleep, temperature, and breathing regulation

midbrain

fiber tract between anterior and posterior brain, optic lobes, and tectum

cerebellum

coordination of complex muscle movement

pons

fiber tracts between cerebellum and cerebrum

medulla

reflex center of involuntary movements

cranial ectodermal placodes

series of epidermal thickenings in the neural tube where the major head sensory organs interact to develop

olfactory placodes

forms ganglia for the olfactory nerves responsible for the sense of smell

auditory placodes

invaginate to form the inner ear labyrinth whose neurons form the acoustic ganglion that enables us to hear

optic vesicle

has direct contact with presumptive lens placode

accomplished by the optic vesicle

the formation of head ectoderm’s latent lens forming ability and positioning of the lens in relation to the retina

optic cup

an optic vesicle that becomes two-walled____ whose walls differentiate in different directions

pigmented retina

outer layer cell will produce melanin pigment and will become

neural retina

cells of the outer layer proliferate rapidly and generate a variety of glia, ganglion cell, and light sensitive photoreceptor neurons collective constitute the

glia, ganglion cells, and light-sensitive photoreceptor neurons

generated by the outer layer of optic cup

ganglion cells

neurons whose axons send electrical impulses to the brain. their axons meet at the base of the eye and travel down to the OPTIC STALK

optic nerve

aka optic stalk

outer layer and inner layer

2 layers of epidermis

periderm

the outer layer will give rise to ____ that will shed once the inner layer differentiates into epidermis

basal layer (stratum or germinativum)

inner layer called ____ is a germinal epithelium that will give rise to all the cell of the epidermis

basal layer, spinous layer

it will divide to give rise to another, outer population of cells constitutes the ____

malpighian layer

basal and spinous layer

malpighian layer

the cells of this layer divide to produce granular layer of the epidermis which is characterized by granules of protein keratin

keratinocytes

cells of granular layer do not divide but differentiate into epidermal skin cells called

keratin granules, cornified layer (stratum corneum)

____ become more prominent as the keratinocytes of the granular layer age and migrate outward to form ___

granular layer

become flattened sacs of keratin protein and their nuclei are pushed to one edge of the cell