Brain Development Flashcards
Neural tube —> brain
Week 4/5
Neurulation
process in which the neural plate bends up and later fuses to form the hollow tube that will eventually differentiate into the brain and the spinal cord of the central nervous system
Neurulation in humans occurs in two distinct phases, what are they?
1.) Primary neurulation
2.) Secondary neurulation
Primary neurulation
during weeks 3 and 4 of gestation leading to development of the brain and spinal cord
Secondary neurulation
during weeks 5 and 6, with formation of the lower sacral and coccygeal cord
What is the purpose of brain development?
- creation of neural tube (brain and spinal cord)
- establishment of brain specific regions
Establishment of brain specific regions:
1.) Neural tube
2.) Primary Brain Vesicles
3.) Secondary Brain Vesicles
4.) Postnatal CNS
Postnatal CNS
- establishment of cranial nerves
- establishment of peripheral nerves
3rd and 4th week of development
- embryo body folding into “C” shape
- 3-Part brain is formed
- at head end –> cephalic and cervical flexures are formed
At the beginning of week 5, cervical flexure doubles back on itself and is the boundary between _________ and __________ ______
hindbrain; spinal cord
Later, the __________ flexure separates the mesencephalon and myelencephalon
pontine
“encephal” =
brain
3 primary vesicles formed during primary neurulation
1.) Prosencephalon
2.) Mesencephalon
3.) Rhombencephalon
Primary Vesicles (3rd and 4th week of development)
As the anterior end of the neural tube starts to develop into the brain, it undergoes a couple of enlargements; the result is the production of sac-like vesicles. Similar to a child’s balloon animal, the long, straight neural tube begins to take on a new shape
Prosencephalon
forebrain
Mesencephalon
midbrain; also the site of the cephalic flexure
Rhombencephalon
- “Rhomb” means a geometric figure with four equal sides
- hindbrain
Secondary Vesicles (5th to 6th week of development)
The brain continues to develop, and the vesicles differentiate further during a process called secondary neurulation
By the 5th-6th week, the three primary vesicles become _____ secondary vesicles
5
5 secondary primary vesicles
1.) Telencephalon (distant)
2.) Diencephalon (2)
3.) Mesencephalon (middle)
4.) Metencephalon (beyond)
5.) Myelencephalon (spinal cord)
Growth between cervical flexure and midbrain –> produces _________ flexure and this divides __________
Pontine; hindbrain
The prosencephalon enlarges into two new vesicles called what?
1.) Telencephalon
2.) Diencephalon
The telencephalon will become what?
cerebrum
The diencephalon gives rise to what adult structures?
1.) Dorsal thalamus
2.) Hypothalamus
In the embryonic diencephalon, a structure known as the _____ ____ also develops, which will eventually become the _____
eye cup; retina
The mesencephalon does or does NOT differentiate into any finer subdivisions?
does NOT
The _______ is an established region of the brain at the primary vesicle stage of development and remains that way
midbrain
The rhombencephalon develops into what two structures?
1.) Metencephalon
2.) Myelencephalon
Metencephalon
corresponds to the adult structure known as the pons and also gives rise to the cerebellum
Cerebellum
(from the Latin meaning little brain) accounts for about 10 percent of the mass of the brain and is an important structure unto itself
The most significant connection between the cerebellum and the rest of the brain is at the _____ because this and the cerebellum develop out of the same vesicle
pons
Myelencephalon
corresponds to the adult structure known as the medulla oblongata
Embryonic telencephalon
- cerebral cortex
- basal ganglia
- hippocampus
- olfactory bulb
- basal forebrain
Embryonic diencephalon
- dorsal thalamus
- hypothalamus
Embryonic mesencephalon
- midbrain
Embryonic metencephalon
- cerebellum
- pons
Embryonic myelencephalon
- medulla oblongata
The brain is developing from the ________ neural tube
anterior
The spinal cord is developing from the ________ neural tube
posterior
The spinal cord does not differ from the basic layout of the neural tube; it is a long straight cord with a small, hollow space down the center; as the neural tube separates from the rest of the ectoderm, the side closest to the surface is _______ and the deeper side is _______
dorsal; ventral
As the spinal cord develops, the cells making up the wall of the neural tube proliferate and differentiate into the ________ and glia of the spinal cord
neurons
Dorsal tissues
associated with sensory functions
Ventral tissues
associated with motor functions
______ ______ houses within brain stem (midbrain, pons, medulla oblongata)
Motor nuclei
