M: Neurulation Flashcards
Ectoderm will soon become:
- Neural tube
- epidermis
the precursor of the Central Nervous System
neural tube
- formed between the epidermis and neural tube
- precursors of the Peripheral Nervous System and pigment cells
neural crest
An embryo undergoing this neurulation is called a __________
neurula
process of differentiation of the ectodermal regions
Neurulation
Levels of__________________ determine ectoderm specification
bone morphogenetic proteins
Cells of the neural plate are characterized by expression of the ________________-, activating genes that specify cells to become the neural plate and blocking the formation of the epidermis and neural crest
Sox family of transcription factors
cells surrounding the neural plate direct cell proliferation, envagination into the embryo, and separation from the ectoderm to form a hollow tube
Primary neurulation
Neural tube arises from an aggregate of mesenchyme cells that form a hollow tube
Secondary neurulation
Primary Neurulation: After the formation of the neural plate, its edges move upward to form the neural folds; the ___________
neural groove
Neural folds migrate towards the _____________ to form the neural tube underneath the ectoderm
midline of the embryo
Epithelial cells in the MHP and DLHP assume a wedge-shaped morphology along the apicobasal axis through:
- Apical constriction
- Basal thickening with retention of the nucleus at the basal portion
- Cell packaging in the neural folds
Stages of Primary Neurulation
- Elongation and folding of neural plate along the rostral-caudal direction
- Bending of the neural plate to form the medial hinge point
- Convergence of the neural folds at the dorsolateral hinge points
- Closure of the neural tube
required for the induction of the neural plate that forms the MHP
Sonic hedgehog morphogen (Shh)
In the DLHP, the _______ morphogen is critical for proper hinge formation and inhibits BMPs
Noggin
The open ends of the neural tube are the:
- anterior neuropore
- posterior neuropore
In humans, there are around five sites of neural tube enclosure:
- The rostal closure site
- Midbrain-forebrain site
- Rostral forebrain site
- Ectoderm cells that gives rise to the posterior neural tube expresses Sox2 genes
- Mesodermal cells express Tbx6 genes
- Junctional neurulation - formation of neural tube between posterior and anterior neural tubes
Secondary Neurulation
Secondary Neurulation: Ectoderm cells that gives rise to the posterior neural tube expresses _______
Sox2 genes
formation of neural tube between posterior and anterior neural tubes
Junctional neurulation
Secondary Neurulation: Mesodermal cells express ___________-
Tbx6 genes
Anterior neural tube differentiates into the
prosencephalon,
mesencephalon,
rhombencephalon
Periodic swelling of the rhombencephalon creates __________________, creating separate “territories” to generate specific neural formations
rhombomeres
Rhombomeres will soon form the _______
ganglia
