At the caudal end of the embryo.
During the 3rd week.
Mesoderm.
Epiblast.
A rod-like structure that starts in the middle of the embryo and proceeds in both cranial and caudal directions.
Axial mesoderm.
Microglia and dura mater.
Hypoblast.
The primitive knot (primitive node) forms at the cranial end.
At the cranial ends of the embryo.
By the beginning of the fourth week.
The underlying notochord and paraxial mesoderm.
During the 3rd week.
Ectoderm (neuroectoderm).
The embryonic midline.
The lateral plate.
Between the paraxial mesoderm and the lateral plate.
The notochord.
A linear band of thickened epiblast cells that first appears at the caudal end of the embryo and grows cranially.
Neural folds.
It provides signals that are essential for the development of surrounding tissues, including the neural tube and vertebral column.
The underlying notochord and paraxial mesoderm.
The Cervical flexure.
Prosencephalon.
Ventricular zone, Mantle layer, and Marginal layer.
The amnion is a membrane that surrounds and protects the embryo, forming the amniotic sac filled with amniotic fluid.
The connecting stalk is the precursor to the umbilical cord, connecting the embryo to the placenta.
The marginal zone.
Cerebrum.
The ventral and lateral grey horns (motor).
It grows cranially.
During the 3rd week.
Pear-shaped.
An invagination of the neural plate.
The raised folds of the neural plate that disconnect from the epidermis.
Prosencephalon (forebrain), Mesencephalon (midbrain), and Rhombencephalon (hindbrain).
The 25th day.
The indentation that forms along the neural plate, which will eventually close to form the neural tube.
The Mantle layer.
The neural crest disconnects from the epidermis.
A linear band of thickened epiblast cells that first appears at the caudal end of the embryo and grows cranially.
Ectoderm (epiblast).
The Marginal layer.
Between the ventricular zone and the marginal zone.
The midbrain is a portion of the brainstem located between the forebrain and the hindbrain.
The mantle zone.
Ventrally.
Pons and Cerebellum.
Failure of neural folds to fuse in midline and form neural tube, and failure of neuropore to close.
It results in a primary defect of Neural Tube Defects (NTDs).
A bulge containing meninges and cerebrospinal fluid (CSF) in the subarachnoid space.
Epiblast and Hypoblast.
It covers the notochord and proliferates to form the paraxial mesoderm.
The nucleus pulposus of the intervertebral discs.
The brain and spinal cord.
The primary brain vesicles.
The Ventricular zone.
A large cranial part and a caudal tubular part.
The forebrain prominence indicates the early development of the forebrain, which will give rise to the cerebral hemispheres.
The ependymal zone.
The basal plate.
It acts as a folate antagonist.
Chlorpheniramine.
The space between the arachnoid mater and the pia mater, containing cerebrospinal fluid.
Telencephalon and Diencephalon.
Ectoderm, mesoderm, and endoderm.
The longitudinal axis of the embryo.
Spinal (DRG) and autonomic ganglia (sympathetic and parasympathetic).
The spinal cord.
The mantle layer.
Neuroblasts, which form neurons.
Folate plays an important role in forming red blood cells and maintaining brain health.
Mesencephalon.
Nutritional deficiencies and hypervitaminosis A, as well as deficient or inadequate maternal vitamin B12.
Alpha-fetoprotein (AFP) levels are increased in maternal serum and amniotic fluid in cases of anencephaly.
There is no bulge over the bony defect.
A cluster of nerve cell bodies in the spinal nerve roots.
The midbrain of the brain stem.
At about 16 days.
It marks the formation of the three primary germ layers: endoderm, mesoderm, and ectoderm.
Ciliary muscles.
Rhombencephalon.
Lateral plate mesoderm, paraxial mesoderm, and neural crest cells.
The yolk stalk connects the yolk sac to the midgut of the developing embryo, providing nutrients during early development.
The lumen becomes rhomboidal.
Hyperthermia.
Anencephaly occurs when the neural tube fails to close at the base of the skull, specifically due to the failure of the rostral neuropore to close.
No, survival is not possible for individuals with anencephaly.
The mesoderm forms skeletal structures (vertebrae and ribs) and muscular structures (back muscles) that cover neural structures.
Occulta and With meningocele.
Meninges and cerebrospinal fluid (CSF).
With meningomyelocele and with myeloschisis.
Metencephalon and Myelencephalon.
In the Rhombencephalon.
In a cranio-caudal direction.
The neural tube.
Endoderm.
Cervically, and it proceeds both cranially and caudally.
On the 25th day.
Adreno-medullary cells, calcitonin C cells of the thyroid gland, and carotid body.
The Dorsal root ganglion.
Melanocytes.
The ventricular zone.
They multiply and newly formed cells move out to form the intermediate zone (mantle layer).
The forebrain is the anterior part of the brain that develops from the neural tube.
1. A pair of alar plates dorsally, 2. A pair of basal plates ventrally, 3. A pair of sulcus limitans in the lateral walls, 4. A roof plate and a floor plate.
Because less than 50% of pregnancies are planned.
The cavity of the neural tube.
The spinal cord develops from the narrow caudal part of the neural tube.
The bones of the skull develop from neural crest cells and paraxial and lateral plate mesoderm.
No, it does not present with neurological symptoms.
A tough membrane that surrounds the spinal cord.
Thalamus, hypothalamus, epithalamus, and retina.
It connects the 3rd and 4th ventricles.
In the Diencephalon.
In meningomyelocele, the spinal cord and meninges protrude through a defect, while in myeloschisis, the spinal cord is exposed and not covered by skin or meninges.
Definite Endoderm, Intraembryonic Mesoderm, and Ectoderm.
The notochord.
The mesoderm that proliferates and forms on either side of the notochord.
In the 3rd week.
Ectoderm (epiblast) dorsally, Endoderm ventrally, and Mesoderm in between.
The cranial and caudal ends of the neural groove are called the anterior (ant.) and posterior (post.) neuropores.
Forebrain, Midbrain, and Hindbrain.
They approximate and fuse together in the midline to form the neural tube.
Surface ectoderm and neuroectoderm.
The nervous system of the embryo.
The optic vesicle is an outgrowth of the forebrain that eventually forms the eyes.
NTDs occur 26 days post-fertilization.
The hindbrain is the posterior part of the brain that develops into structures such as the cerebellum, pons, and medulla oblongata.
Sulcus limitans.
The dorsal grey horn (sensory).
Substances that cause congenital disorders in a developing embryo or fetus.
The skeletal (vertebrae and ribs) and muscular (back muscles) structures that cover neural structures.
No bulge over the bony defect.
It is a protective membrane surrounding the spinal cord.
A bulge containing meninges, cord, and nerves.
Prosencephalon, Mesencephalon, Rhombencephalon.
Medulla oblongata.
It determines the orientation of the vertebral column.
In a median area on the dorsal aspect of the embryonic disc.
Neural folds.
Mesencephalon.
The axial skeleton (vertebral & ribs).
Tissues on the outer surface of the body like epidermis, hair, and nails.
The Marginal layer.
The midbrain flexure is a bend in the neural tube that occurs in the midbrain region during development.
They competitively inhibit enzymes that function in the synthesis of folic acid.
A skin dimple or a tuft of hairs.
The vertebral arch.
Meninges, cord, and nerves.
In meningomyelocele, a bulge containing meninges, cord, and nerves is seen over the defect, while in myeloschisis, the open spinal cord is seen as a mass of neural tissue over the bony defect.
Cerebrum: cerebral hemispheres (cortex, white matter, basal nuclei).
A severe form of spina bifida where the spinal cord is exposed through a gap in the spine and is not covered by skin or meninges.
On the 27th day.
The cranial part of the neural tube.
The Midbrain flexure.
Neural plate, neural fold, neural crest, neural tube, surface ectoderm, paraxial mesoderm, notochord, yolk sac.
Telencephalon and Diencephalon.
Folic acid is protective only if ingested during the preconception period.
Roof plate and floor plate.
Medulla oblongata.
At 3 weeks.
At 7 weeks.
Over unfused vertebral arches.
Pons and cerebellum.
In the Telencephalon.
Bone and cartilage of the facial skeleton.
A thick layer of neuroepithelium.
Superficial to the ventricular zone.
The heart prominence is the early formation of the heart, which will eventually develop into the fully functional heart.
The cervical flexure is a bend in the neural tube that occurs between the hindbrain and the spinal cord.
Thalamus.
Parts of the brainstem.
Valproic acid (sodium valproate, e.g., Depakine).
A skin dimple or a tuft of hairs may be present.
Leptomeninges (pia & arachnoid) and Schwann cells.
The Optic vesicle.
The 27th day.
Somites are blocks of mesoderm that segment the body of the embryo and give rise to the vertebrae, ribs, and skeletal muscles.
The narrow caudal part of the neural tube.
Genetic factors and folate deficiency.
Dorsally.
Metencephalon and Myelencephalon.
It leads to Neural Tube Defects (NTDs).
The dorsal root ganglion contains the cell bodies of sensory neurons and is crucial for transmitting sensory information to the spinal cord.
The alar plate.
Anencephaly is one of the most common neural tube defects (NTDs) characterized by the absence of the calvarium, posterior bone elements (skull), and deficiency in the brain (prosencephalus) and meninges.
No, there are no neurological symptoms.
An open spinal cord seen as a mass of neural tissue.
A form of spina bifida where the spinal cord and meninges protrude through a defect in the vertebral column.
At 11 weeks.
A sac that contains the displaced spinal cord and roots of the spinal nerve.
