1 Flashcards
is the development of the specific tissues and organs of the body.
Organogenesis
Organs that perform related functions are grouped into a
System
How many organ system does the body has?
11
Central nervous system is composed of?
Brain and spinal cord
Are the basic functional unit of the CNS
Neurons ( nerve cells)
The connective tissue cells of the CNS are the
gliocytes
(oligodendrocytes, astrocytes, microgliocytes and ependymal cells).
which contains cytoplasm and nucleus;
nerve cell body
which conducts impulses away from the cell body
Axon
The axon presents at its
end many tiny branches called
Telodendria
where impulses leave the neuron
Telondria
which receive stimuli from the environment and convert these stimuli into
impulses.
Dendrites
Axon only
Unipolar neuron
neuron w/ only one process
Unipolar neuron
axon & dendrite
Bipolar neuron
neuron w/ two processes
Bipolar neuron
neuron w/ many processes
Multipolar neuron
One axon & and many dendrites
Multipolar neuron
Enlarged cranial portion of the neural tube becomes the
Brain
The slender middle and caudal portions become the
Spinal cord
Neural canal becomes the …….
ventricles of the brain and the central canal of the
spinal cord.
Neural crest cells become
(1) neurons of the PNS that have their cell bodies in
ganglia,
(2) neurolemocytes (Schwann cells) of the PNS,
(3) adrenal medulla
cells,
(4) melanocytes of skin and
(5) a variety of structures in the face.
Neuroepithelium gives rise to
neurons, gliocytes and ependymal cells of the CNS.
CNS contains….
blood vessels and
microgliocyte derived from mesoderm
inner layer; composed of neuroepithelial
cells that remain lining the central canal and designated as ependymal cells
Germinal layer or ventricular zone
middle layer; zone of high cell density,
formed by accumulation of neuroblasts and glioblasts
Mantle layer or intermediate zone
becomes the gray matter of
the CNS w/c contains cell bodies of neurons & several gliocytes.
Mantle layer or intermediate zone
The outer layer surrounding the mantle layer; cell-sparse zone
where axons of neurons & some gliocytes are present;
Marginal layer
becomes the white matter
of the CNS which contains mainly myelinated axons of neurons.
Marginal layer
The lateral wall of the neural tube is divided into 2 plates by sulcus limitans
Alar or dorsal plate
Basal or ventral plate
a bilateral indentation in the neural cavity
that serves as a landmark to divide the wall
Sulcus limitans
contains cell bodies of
efferent or motor neurons that send axons into the PNS
Basal plate
contains neurons that
receive afferent or sensory input from the PNS.
Alar plate
Midline region of the wall dorsal to the neural canal constitutes the
roof plate
counterpart wall ventral to the neural canal is the
Floor plate
How many hours the incubaton of chick embryo the enlarged cranial end of the neural
tube forms 3 brain vesicles?
27 hrs
occupies the rostral part of the head
Prosencephalon (forebrain)
Neural canal is prosocoele; presents a depression on its floor, the infundibulum;
Prosencephalon (forebrain)
Neural canal
is prosocoele; presents a depression on its floor, the
Infundibulum
located posterior to and marked off from the
prosencephalon by constriction
Mesencephalon (midbrain)
In mesencephalon the neural canal is
Mesocoele
located posteriorly and marked off from the
mesencephalon by a slight constriction.
Rhombencephalon (hindbrain)
Rhombencephalon (hindbrain) located posteriorly and marked off from the
mesencephalon by a slight constriction. Neural canal is
Rhombocoele
continuous posteriorly w/ the spinal cord
Rhombocoele
that will develop into brain presents 11 enlargements
The cranial neural tube
The cranial neural tube that will develop into brain presents 11 enlargements
called
Neuromeres
are a sign of metamerism or segmentation in the embryo
Neuromeres
Neuromeres…..
I to III make up the prosencephalon, neuromeres IV
V, the mesencephalon
VI to XI, the rhombencephalon.
How many hrs of incubation, the lateral walls of prosencephalon evaginate
to form two primary optic vesicles?
29-30hrs
The rostral end of prosencephalon presents the
___________ that is almost closed by 33 hrs of incubation
Anterior neuropore
occurs at the level of the midbrain; concave ventrally
Midbrain flexure
occurs between the midbrain and the hindbrain; concave
dorsally.
Pontine flexure
appears at the junction of the hindbrain and spinal cord;
persists slightly in domestic animals; concave ventrally.
Cervical flexure
By 38 hours of incubation, three brain vesicles become four due to the division of
the rhombencephalon into metencephalon (VI - VII) and myelencephalon (VIII - XI).
Rhombocoele of metencephalon is metacoele; that of the myelencephalon is the
myelocoele.
By 55 hours of incubation the prosencephalon shows evidence of division into the …..
cephalic telencephalon and caudal diencephalon, the latter being composed of the
optic vesicles and part of prosencephalon lying between the optic vesicles
By 72 hours of incubation, the telencephalon presents a median portion called
median telencephalon
2 lateral evagination called
lateral telencephalic vesicles.
Prosocoele of median telencephalon is the
Median telecoele
while the prosocoele of the
lateral telencephalic vesicles are the
lateral telocoele
Neural canal becomes the
Central canal
failure of cerebellum to develop due to
destruction of cerebellar cortex.
Cerebellar hypoplasia and atrophy
premature degeneration of Purkinje cell layer of
cerebellar cortex.
Cerebellar abiotrophy
accumulation of excessive amount of cerebrospinal fluid in the
cranial cavity.
Hydrocephalus
thin walled and greatly enlarged lateral ventricle filled with
CSF.
Hydranencephaly
general term for a malformation of the spinal cord. Originates
during neurula.
Myelodysplasia
reduced or absence of development of one or
more segments of spinal cord.
Hypoplasia (aplasia)
dilation of central canal due to excess accumulation of
CSF.
Hydromyelia
abnormal cavitation of the spinal cord.
Syrinomyelia
2 spinal cords develop beside each other usually in one set
or meninges and in one vertebral canal
Diplomyelia
2 spinal cords develop w/ a partition between them.
Usually in separate vertebral canals and have separate meninges.
Diastematomyelia
cleft in the neural tube brought about by the failure of this part to close
during neurulation.
Myeloschisis
protrusion of the meninges through an opening in the vertebral
arches to form a cyst beneath the skin.
Meningocoele
similar to meningocoele except that both meninges and
spinal cord protrudes
Meningomyelocoele
Are associated with spina bifida
Myelochisis
Meningocoele
Meningomyelocoele
the failure of vertebral arches to close dorsal to spinal cord.
Spina bifida
