Nervous System Development Flashcards
The notochord will induce the primitive ectoderm to form which of the following structures?
- neural crests
- neural folds
- neural plate
neural plate
Explanation
On ~ day 16 of gestation the notochord (formed by cells in the mesoderm layer of the embryo) will induce the overlying cells in the ectoderm to form the neural plate. The neural plate will thicken at its margins on ~ day 18 of gestation forming the neural folds. The neural crests form from lateral portions of the neural folds that break off when the folds form the neural tube.
When the neural folds contact each other during in-folding on day 20 of gestation, this is the beginning of the formation of the neural tube.
True or False
True
Explanation
This statement is true: at day 20 the neural folds will contact each other to begin the formation of the neural tube.
The neural tube is considered fully formed with the closing of the anterior neuropore on day________ and the closing of the posterior neuropore on day_______________
18; 20
24; 26
20; 42
24; 26
Explanation
The neural tube is considered fully formed with the closure of the anterior neuropore which takes place on ~ day 24, and the closure of the posterior neuropore which takes place on day 26. The key event taking place on day 18 is the formation of the neural folds; the key event taking place on day 20 is the beginning of the formation of the neural tube with the initial contact of the neural folds; days 20 - 42 mark the period of secondary neurulation.
Which of the following cell layers (zones) on the lumen of the neural tube will merge together to form the basal and alar plates?
- ventricular and intermediate zones
- intermediate and marginal zones
- ventricular and marginal zones
ventricular and intermediate zones
Explanation
Along the lumen of the neural tube, cells will proliferate forming the ventricular zone (these cells will become the neurons, glial cells, and ependymal cells). The processes of the developing cells will produce marginal layer. Cells in the ventricular zone will migrate to from what is called the intermediate zone. The ventricular and intermediate zones fuse to form 4 longitudinal plates: 2 basal plates (located anteriorly giving rise to motor neurons) and 2 alar plates (located posteriorly - giving rise to sensory neurons).
The process of primary neurulation gives rise to the portion of the neural tube that develops the brain and the spinal cord through the lumbar levels, and the process of secondary neurulation gives rise to the remainder of the spinal cord.
True or False
True
Explanation
This statement is true: primary neurulation will give rise to the portion of the neural tube that will develop into the brain and the spinal cord through the lumbar levels; the remainder of the spinal cord develops during secondary neurulation.
Failure of the anterior neuropore to close can result in spina bifida.
True
False
False
Explanation
Failure of the anterior neuropore to close results in either anencephaly or an encephalocele.
Which of the following is considered the most severe form of an encephalocele?
Meningocele
Meningohydroencephalocele
Meningoencephalocele
Meningoencephalocele
Explanation
Encephaloceles are defects in the cranium that invovle various degress of hernination of intracranial contents. A meningohydroencephaloce is considered the most severe form. It is a cystic structure that contains meninges, brain tissue & part of the ventricular system. A meningocele is the mildest form and consists of a cystic structure that contains only meninges. A meningoencephalocele is a cystic structure that contains meninges and brain tissue.
Which of the following can be caused by failure of the posterior neuropore to close? Select all that apply.
Spina bifida occulta
Meningomyelocele
Meningoencephalocele
Tethered cord syndrome
Spina bifida occulta
Meningomyelocele
Explanation
The spina bifidas (occulta and cystica (which includes a meningocele or a meningomyelocele) result from failure of the posterior neuropore to close. Meningoencephalocele is an encephalocele and tethered cord syndrome results from defective secondary neurulation.
Which of the following are considered primary brain vesicles? Select all that apply.
Posencephalon
Telencephalon
Mesencephalon
Metencephalon
Rhombencephalon
Posencephalon, Mesencephalon, Rhombencephalon
Explanation
The three primary brain vesicles include the prosencephalon (forebrain), mesencephalon (midbrain), and the rhombencephalon (hindbrain). The telencephalon and metencephalon are considered secondary brain vesicles.
The rhombencephalon will divide to become the__________and ___________.
telencephalon; diencephalon
mesencephalon; metencephalon
metencephalon; myelencephalon
metencephalon; myelencephalon
Explanation
The rhombencephalon will divide creating the metencephalon and the myelencephalon. The prosencephalon will divide creating the telencephalon and the diencephalon. The mesencephalon doesn’t divide and remains the mesencephalon.
Which brain vesicle gives rise to the cerebral cortex?
Telencephalon
Diencephalon
Metencephalon
Myelencephalon
Telencephalon
Explanation
The telencephalon become the cerebral cortex, subcortical white matter, olfactory bulb, basal nuclei, amygdala, and the hippocampus; the diencephalon becomes the thalamus, subthalamus, hypothalamus, and the epithalamus; the metencephalon becomes the pons and cerebellum; and the myelencephalon becomes the medulla. The mesencephalon (not listed) becomes the midbrain.
The cavity of which of the following brain vesicle becomes the cerebral aqueduct?
Telencephalon
Diencephalon
Mesencephalon
Mesencephalon
Explanation
The cavity of the mesencephalon (midbrain) becomes the cerebral aqueduct (which is the communication between the 3rd and 4th ventricles. The cavity of the telencephalon becomes the lateral ventricles (there are 2); the cavity of the diencephalon becomes the 3rd ventricle and (not listed) the cavity of the rhombencephalon becomest the forth ventricle.
