What does the Morula become?
A distinct inner and outer cell mass
A trilaminar embryo
The epiblast and hypoblast
The inner cell mass differentiates into which two structures?
The primitive streak indicates that gastrulation is occurring.
What is gastrulation?
The migration of epiblast cells to the primitive streak which then migrates down and displaces the hypoblast, forming a trilaminar embryo consisting, in descending order, of the ectoderm, mesoderm and endoderm.
The folding of the parietal and visceral layers of the lateral plate mesoderm in order to form the precursors to the bone and wall of the gut tube respectively.
The formation of the notochord from the notochordal plate in a cranial to caudal sequence.
The Ectoderm is destined to become what structures?
The Mesoderm is destined to become which structures?
The Endoderm is destined to become which structures?
The Notochord is important in signal secretion for nervous system development.
The primitive node is the "organiser" of the trilaminar embryo, and releases signalling molecules like NODAL, BMP4 and Noggin.
Neurulation is the formation of the neural tube. The embryonic plate elongates and folding creates a neural groove and neural plate. Somites, ridges either side of the groove form. Continued folding leads to a tube structure forming. The anterior and posterior neuropores then close, forming a neural tube.
The notochord release BMP that patterns the ventral side of the neural tube.
BMP is released which patterns the dorsal side of the neural tube.
Spina Bifida is caused by what?
Failure of the neural tube to close
Failure of neural crest cells to migrate
Failure of gastrulation
Mutations in SHH can lead to what?
Cyclopsia due to lack of bilateral symmetry
Inverted organ symmetry due to lack of wafting
The mesoderm differentiates into which layers?
Lateral plate - Parietal and Visceral layers
Folding of the parietal layer of the lateral plate mesoderm produces the precursor to the GI tract.
Somites differentiate into what three 'tomes'?
HOX genes are not responsible for coding for particular segments of body structures
Pharyngeal arches are located where?
Ectodermal side - ridges
Endodermal side - ridges
Endodermal side - pits
Ectodermal side - pits
There are 5 pharyngeal arches; 1st, 2nd, 3rd, 4th, 6th.
Neural crest cell migration is important in forming the ectodermal placodes. The crest cells aid in the formation of sensory ganglia of certain cranial nerves. Which cranial nerves are these and what conditions may result due to migration failure?
CN 5, 7, 9 and 10
CN 5, 7, 8 and 10
CN 1, 3, 10 and 12
CN 2, 4, 9 and 11
Migrated neural crest cells can form 'cartilages' in the arches such as Meckel's cartilage. What is its function?
Precursor template for the mandible
Signal secretion for the developing embryo
Formation of the sensory ganglia in the arches
Which cranial nerve innervates the 1st pharyngeal arch?
Which cranial nerve innervates the 2nd pharyngeal arch?
Which cranial nerve innervates the 3rd pharyngeal arch?
Which cranial nerve innervates the 4th and 6th pharyngeal arches?
Which components of the skull are made from the 1st pharyngeal arch?
Which components of the skull are made from the 2nd pharyngeal arch?
Which components of the skull are made from the 4th and 6th pharyngeal arches?
The medial and lateral nasal prominences join together to make the nose.
The fusion of the medial nasal prominences forms the secondary palate
The maxillary prominences fuse together to form the secondary palate
What condition(s) are caused by failure of the nasal, mandibular and maxillary prominences to fuse?