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Questions and Answers
What type of cells myelinate the optic nerve?
What type of cells myelinate the optic nerve?
Which condition results from the failure of closure of the choroid fissure?
Which condition results from the failure of closure of the choroid fissure?
Which component is part of the middle ear?
Which component is part of the middle ear?
Which structures are derived from the first and second pharyngeal arches?
Which structures are derived from the first and second pharyngeal arches?
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What does the definitive tympanic membrane derive from?
What does the definitive tympanic membrane derive from?
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What happens to the optic nerve after transection?
What happens to the optic nerve after transection?
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Which structure does the otic placode develop into?
Which structure does the otic placode develop into?
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What is congenital cataracts primarily associated with?
What is congenital cataracts primarily associated with?
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What is the primary developmental origin of neural crest cells?
What is the primary developmental origin of neural crest cells?
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Which of the following structures can be formed from neural crest cells?
Which of the following structures can be formed from neural crest cells?
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What condition is characterized by a failure of neural crest cell migration into the bowel wall?
What condition is characterized by a failure of neural crest cell migration into the bowel wall?
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Which embryological abnormality is linked to the development of coloboma in the eye?
Which embryological abnormality is linked to the development of coloboma in the eye?
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In Hirschsprung's disease, which segment of the bowel is primarily affected?
In Hirschsprung's disease, which segment of the bowel is primarily affected?
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What type of transition do neural crest cells undergo during their development?
What type of transition do neural crest cells undergo during their development?
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Which of the following is NOT a derivative of neural crest cells?
Which of the following is NOT a derivative of neural crest cells?
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What are the characteristic symptoms of Hirschsprung's disease?
What are the characteristic symptoms of Hirschsprung's disease?
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What structure does the hyaloid artery later develop into?
What structure does the hyaloid artery later develop into?
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During which week does the lens vesicle lose contact with the surface ectoderm?
During which week does the lens vesicle lose contact with the surface ectoderm?
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The outer layer of the developing mesenchyme around the eye primordium forms which structure?
The outer layer of the developing mesenchyme around the eye primordium forms which structure?
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Which component of the inner wall of the optic cup contributes to the iris?
Which component of the inner wall of the optic cup contributes to the iris?
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What is formed as a result of vacuolization in the anterior mesenchyme?
What is formed as a result of vacuolization in the anterior mesenchyme?
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What is the role of the optic stalk during eye development?
What is the role of the optic stalk during eye development?
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Which layer distinguishes the posterior five-fifths of the inner wall of the optic cup?
Which layer distinguishes the posterior five-fifths of the inner wall of the optic cup?
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What happens to the choroid fissure during the seventh week of development?
What happens to the choroid fissure during the seventh week of development?
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What is the earliest sign of eye development observed in the embryo?
What is the earliest sign of eye development observed in the embryo?
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Which embryonic structure is responsible for forming the retina and optic nerve in adulthood?
Which embryonic structure is responsible for forming the retina and optic nerve in adulthood?
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What occurs when the optic vesicles come into contact with the surface ectoderm?
What occurs when the optic vesicles come into contact with the surface ectoderm?
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Which cells migrate into the mesenchyme and contribute to the formation of the choroid and sclera?
Which cells migrate into the mesenchyme and contribute to the formation of the choroid and sclera?
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What happens to the intraretinal space during the development of the optic cup?
What happens to the intraretinal space during the development of the optic cup?
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What are the two germ layers from which the definitive eardrum is derived?
What are the two germ layers from which the definitive eardrum is derived?
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Which congenital malformation is NOT associated with the pharyngeal arches?
Which congenital malformation is NOT associated with the pharyngeal arches?
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Which part of the pharyngeal apparatus contributes to the formation of external auditory meatus?
Which part of the pharyngeal apparatus contributes to the formation of external auditory meatus?
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What type of tissue primarily makes up each pharyngeal arch?
What type of tissue primarily makes up each pharyngeal arch?
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What is the main role of neural crest cells in the development of pharyngeal arches?
What is the main role of neural crest cells in the development of pharyngeal arches?
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What condition is characterized by the absence of the external ear?
What condition is characterized by the absence of the external ear?
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Which pharyngeal arch is dominated by the maxillary and mandibular processes?
Which pharyngeal arch is dominated by the maxillary and mandibular processes?
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The tympanic membrane is formed from which of the following?
The tympanic membrane is formed from which of the following?
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What does the outer layer of the undifferentiated mesenchyme around the eye primordium develop into?
What does the outer layer of the undifferentiated mesenchyme around the eye primordium develop into?
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Which structure is formed from the anterior chamber through vacuolization?
Which structure is formed from the anterior chamber through vacuolization?
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What structure does the hyaloid artery transform into during development?
What structure does the hyaloid artery transform into during development?
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Which of the following layers forms the inner layer of the iris?
Which of the following layers forms the inner layer of the iris?
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During which week does the fusion of the lips of the choroid fissure occur?
During which week does the fusion of the lips of the choroid fissure occur?
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What space is defined as being between the iris and the lens during eye development?
What space is defined as being between the iris and the lens during eye development?
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The mesoderm present between the optic cup and overlying surface epithelium contributes to which structures?
The mesoderm present between the optic cup and overlying surface epithelium contributes to which structures?
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What does the optic stalk develop into as it matures during eye development?
What does the optic stalk develop into as it matures during eye development?
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What is the primary consequence of failed neural crest cell migration in Hirschsprung's disease?
What is the primary consequence of failed neural crest cell migration in Hirschsprung's disease?
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Which embryological structure gives rise to the cranial nerve ganglia?
Which embryological structure gives rise to the cranial nerve ganglia?
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What abnormality results from issues in the development of neural crest cells associated with the face?
What abnormality results from issues in the development of neural crest cells associated with the face?
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What is the primary function of the neural crest cells during early development?
What is the primary function of the neural crest cells during early development?
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Which condition does not typically involve neural crest cell derivatives?
Which condition does not typically involve neural crest cell derivatives?
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What outcome is associated with the abnormal development of the eye, such as coloboma?
What outcome is associated with the abnormal development of the eye, such as coloboma?
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How does congenital deafness relate to the development of structures derived from neural crest cells?
How does congenital deafness relate to the development of structures derived from neural crest cells?
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Which structure is NOT formed by the migration of neural crest cells during embryonic development?
Which structure is NOT formed by the migration of neural crest cells during embryonic development?
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Which statement about the developmental process of the optic nerve is true?
Which statement about the developmental process of the optic nerve is true?
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Which of the following conditions is specifically associated with a failure of closure of the choroid fissure?
Which of the following conditions is specifically associated with a failure of closure of the choroid fissure?
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What structures contribute to the formation of the definitive tympanic membrane?
What structures contribute to the formation of the definitive tympanic membrane?
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Which feature defines the dual origin of the ear's components?
Which feature defines the dual origin of the ear's components?
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What is a primary characteristic of the development of the semicircular canals?
What is a primary characteristic of the development of the semicircular canals?
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Which of the following accurately reflects the relationship between the ossicles and the pharyngeal arches?
Which of the following accurately reflects the relationship between the ossicles and the pharyngeal arches?
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What developmental outcome is linked to the persistence of the iridopupillary membrane?
What developmental outcome is linked to the persistence of the iridopupillary membrane?
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Which of the following statements about the auditory tube is correct?
Which of the following statements about the auditory tube is correct?
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Which embryonic structures are primarily responsible for the formation of the retina and optic nerve in adulthood?
Which embryonic structures are primarily responsible for the formation of the retina and optic nerve in adulthood?
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What occurs during the contact of the optic vesicles with the surface ectoderm?
What occurs during the contact of the optic vesicles with the surface ectoderm?
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Which embryonic layer contributes to the fibrous and vascular coats of the eye?
Which embryonic layer contributes to the fibrous and vascular coats of the eye?
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What is the earliest recognizable sign of eye development in the embryo?
What is the earliest recognizable sign of eye development in the embryo?
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Which structure forms due to the invagination of the optic vesicles?
Which structure forms due to the invagination of the optic vesicles?
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Which of the following congenital anomalies is specifically linked to abnormalities in the first and second pharyngeal arches?
Which of the following congenital anomalies is specifically linked to abnormalities in the first and second pharyngeal arches?
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What is the primary tissue type found in the core of each pharyngeal arch?
What is the primary tissue type found in the core of each pharyngeal arch?
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Which of the following conditions is typically associated with inner ear deafness?
Which of the following conditions is typically associated with inner ear deafness?
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From which pharyngeal cleft is the external auditory meatus derived?
From which pharyngeal cleft is the external auditory meatus derived?
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Which embryonic structure develops into the definitive tympanic membrane?
Which embryonic structure develops into the definitive tympanic membrane?
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What primarily contributes to the genetic derivatives of the pharyngeal arches?
What primarily contributes to the genetic derivatives of the pharyngeal arches?
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Which process occurs as a result of the overlapping of mesenchymal tissue in the second arch?
Which process occurs as a result of the overlapping of mesenchymal tissue in the second arch?
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Which of the following components is characteristic of each pharyngeal arch?
Which of the following components is characteristic of each pharyngeal arch?
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Study Notes
Neural Crest, Eye, and Ear
- Learning Outcomes: The presentation outlines learning objectives, including describing neural crest cell origins and migration, explaining pathologies like Hirschsprung's disease, detailing eye and ear development, and describing pharyngeal arches and their derivatives.
Neural Crest Cells
- Definition: Neural crest cells are a special cell population located at the lateral border of the neuroectoderm.
- Dissociation: These cells detach from their neighbors as the neural folds elevate and fuse to form the neural tube.
- Transition: The cells undergo an epithelial-to-mesenchymal transition.
- Migration: They migrate actively to various locations in the body, giving rise to diverse structures.
Neural Crest Derivatives
- Connective Tissue and Bones: These cells contribute to face and skull structure.
- Cranial Nerve Ganglia: They form ganglia associated with cranial nerves.
- C Cells of the Thyroid Gland: Neural crest cells are involved in the development of C cells within the thyroid gland.
- Conotruncal Septum: Development of this heart structure is influenced by neural crest cells.
- Odontoblasts: Neural crest cells differentiate into these specialized cells crucial for tooth formation.
- Dermis: Neural crest cells play a role in the formation of the facial dermis.
- Spinal Ganglia: Neural crest cells are necessary for the development of spinal ganglia.
- Sympathetic Chain and Pre-aortic Ganglia: Neural crest cells contribute to autonomic nervous system components.
- Parasympathetic Ganglia: These ganglia in the gastrointestinal tract originate from neural crest cells.
- Adrenal Medulla: Neural crest cells are the precursors for the cells in the adrenal medulla.
- Schwann Cells: These cells necessary for the proper function of the peripheral nervous system develop from neural crest cells.
- Glial Cells: These supporting cells of the nervous system originate from neural crest cells, especially within the forebrain.
- Melanocytes: Neural crest cells give rise to these pigment-producing cells.
- Smooth Muscle Cells: These cells in blood vessels in the face and forebrain develop from neural crest cells.
Hirschsprung's Disease
- Cause: Failure of neural crest cell migration into the bowel wall.
- Pathology: These cells are needed to develop the parasympathetic (Auerbach's and Meissner's) plexus.
- Clinical Presentation: The affected region is typically in the sigmoid and rectum.
- Characteristics**: Delayed passage of meconium, constipation, vomiting, and abdominal distension are typical signs.
Eye Development
- Sources: Neuroectoderm of the forebrain, surface ectoderm of the head, mesoderm between the previous two layers, and neural crest cells are involved in eye formation.
- Earliest Sign: A pair of shallow grooves on each side of the forebrain of a 22-day embryo indicates the initial stage of eye formation.
Optic Cup & Lens Vesicle
- Origin: Optic vesicles form from outpocketings of the forebrain.
- Contact: Lens vesicle arises from the contact with the surface ectoderm, which then prompts changes.
- Invagination: Optic vesicles invaginate to form a double-walled optic cup.
- Intraretinal Space: The initial optic cup inner and outer walls are separated by an intraretinal space that eventually closes.
Development of Eye Embryonic Structure
- Neuroectoderm: Gives rise to the retina, posterior iris layers, and optic nerve.
- Surface Ectoderm: Forms the lens of the eye and corneal epithelium.
- Mesoderm: Involved in the development of the fibrous and vascular coats of the eye.
- Neural Crest Cells: Migrate to the mesenchyme and differentiate into the choroid, sclera, and corneal endothelium.
Choroid, Sclera, and Cornea
- Origin: Undifferentiated mesenchymal cells around the eye primordial contribute to the choroid and sclera.
- Mesenchymal Differentiation: These cells differentiate into two layers.
- Inner Layer: Forms the highly vascularized and pigmented choroid.
- Outer Layer: This layer develops into the sclera.
Anterior Chamber
- Formation**: The anterior chamber is created through vacuolisation, splitting the mesenchyme.
- Inner Layer**: This layer forms the iridopupillary membrane, which eventually disappears.
Posterior Chamber
- Location**: This chamber lies between the iris anteriorly and the lens and ciliary body posteriorly.
Development of the Ear
- Dual Origin: Thickened ectodermal placode at the rhombencephalon (hindbrain) and first and second pharyngeal arches.
- Otic Vesicle Formation: Induction from rhombencephalon and surface ectoderm results in otic placode transformation into otic vesicles.
- Membranous Labyrinth: Otic vesicles, further developing, creates the saccule, cochlear duct, utricle and semicircular canals.
Pharyngeal Arches
- Function: Development of the neck and face.
- Components: Each arch consists of skeletal, muscular, vascular, and neural components.
- Derivatives: Cartilages, muscles, and nerves come from specific pharyngeal arches.
Pharyngeal Clefts
- Formation: Only the first cleft becomes the external auditory meatus.
- Tympanic Membrane: The epithelial lining of the pharyngeal membrane forms the tympanic membrane (eardrum).
- Cervical Sinus: The clefts form a cavity lined by ectodermal epithelium, but later disappear.
Clinical Correlates
- Eye Anomalies: Coloboma iridis, persistence of iridopupillary membrane, aniridia, cyclopia, congenital aphakia, and congenital cataracts are discussed.
- Ear Anomalies: Congenital deafness and auricular abnormalities (microtia, anotia, accessory tragus, preauricular pits or sinuses)
1st Arch Defect
- Mandibulofacial dysostosis: A disorder associated with 1st pharyngeal arch defects.
- Autosomal dominant: Inheritance pattern of the condition.
- Clinical features: micrognathia, poor mandible growth, cleft palate, glossoptosis, and other issues are common symptoms.
3rd & 4th Pouch Syndrome
- Clinical Presentation: Absence of thymus, parathyroid glands, persistent truncus arteriosus, abnormal external ear features, and micrognathia are observed.
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Description
This quiz covers the origins and migration of neural crest cells, and their role in the development of the eye and ear. It also addresses significant pathologies such as Hirschsprung's disease and the function of pharyngeal arches. Test your knowledge on the derivatives of neural crest cells and their contributions to various structures in the body.
