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Questions and Answers
What type of cleavage occurs in birds?
What type of cleavage occurs in birds?
- Discoidal meroblastic (correct)
- Radial
- Holoblastic
- Irregular
The area pellucida is the opaque region surrounding the area opaca.
The area pellucida is the opaque region surrounding the area opaca.
False (B)
What is the role of the primitive streak in embryonic development?
What is the role of the primitive streak in embryonic development?
It defines the axis of the embryo.
The ______ is the thickening of the epiblast at the posterior region of the embryo.
The ______ is the thickening of the epiblast at the posterior region of the embryo.
Match the following terms with their definitions:
Match the following terms with their definitions:
Which of the following correctly describes the two-layered blastoderm?
Which of the following correctly describes the two-layered blastoderm?
Cells passing through the lateral portions of the primitive streak mainly form ectodermal tissues.
Cells passing through the lateral portions of the primitive streak mainly form ectodermal tissues.
What is the functional equivalent of the dorsal lip of the amphibian blastopore in birds?
What is the functional equivalent of the dorsal lip of the amphibian blastopore in birds?
What is the fate of the paraxial mesoderm?
What is the fate of the paraxial mesoderm?
What is the primary function of the cerebellum?
What is the primary function of the cerebellum?
The notochord plays a significant role in signaling and patterning surrounding tissues during development.
The notochord plays a significant role in signaling and patterning surrounding tissues during development.
What do somites derive from?
What do somites derive from?
The surface ectoderm gives rise to Schwann cells, which myelinate peripheral nerves.
The surface ectoderm gives rise to Schwann cells, which myelinate peripheral nerves.
The splanchnic (visceral) layer of the lateral plate mesoderm forms the ______ and the vascular system.
The splanchnic (visceral) layer of the lateral plate mesoderm forms the ______ and the vascular system.
What is the role of the pons in the brain?
What is the role of the pons in the brain?
Match the following mesoderm types with their corresponding fates:
Match the following mesoderm types with their corresponding fates:
The neuroectoderm ultimately develops into the _____ and _____ systems.
The neuroectoderm ultimately develops into the _____ and _____ systems.
Which structures are derived from myotome?
Which structures are derived from myotome?
Match the following parts of the rhombencephalon with their functions:
Match the following parts of the rhombencephalon with their functions:
The heart tube is formed from the merging of pre-cardiac mesoderm.
The heart tube is formed from the merging of pre-cardiac mesoderm.
Which structure in the myelencephalon is responsible for vital autonomic functions?
Which structure in the myelencephalon is responsible for vital autonomic functions?
What does the intermediate mesoderm form?
What does the intermediate mesoderm form?
The fourth ventricle is located between the cerebellum and the pons.
The fourth ventricle is located between the cerebellum and the pons.
What is the primary purpose of the heart tube's looping during development?
What is the primary purpose of the heart tube's looping during development?
What developmental stage of many vertebrates shows the division of the rhombencephalon into rhombomeres?
What developmental stage of many vertebrates shows the division of the rhombencephalon into rhombomeres?
The midgut develops into the esophagus and part of the stomach.
The midgut develops into the esophagus and part of the stomach.
What structures will the lung buds eventually give rise to?
What structures will the lung buds eventually give rise to?
The _____ is the part of the gut tube that will develop into the large intestine.
The _____ is the part of the gut tube that will develop into the large intestine.
Match the following gut tube sections with their corresponding developments:
Match the following gut tube sections with their corresponding developments:
Where does the pancreas begin to develop during embryonic growth?
Where does the pancreas begin to develop during embryonic growth?
What does the olfactory placode give rise to?
What does the olfactory placode give rise to?
The thyroid gland is formed from mesodermal tissue.
The thyroid gland is formed from mesodermal tissue.
What eventually forms from the differentiation of the endoderm in the pharyngeal pouches?
What eventually forms from the differentiation of the endoderm in the pharyngeal pouches?
What is the primary role of Hensen's node in chick embryology?
What is the primary role of Hensen's node in chick embryology?
The ectoderm contributes to the formation of the enamel of teeth.
The ectoderm contributes to the formation of the enamel of teeth.
The area pellucida is characterized by a dark appearance.
The area pellucida is characterized by a dark appearance.
What structures do auditory placodes give rise to?
What structures do auditory placodes give rise to?
The epithelial layer of the cornea is formed by the surface __________.
The epithelial layer of the cornea is formed by the surface __________.
What forms the head mesenchyme and prechordal plate mesoderm?
What forms the head mesenchyme and prechordal plate mesoderm?
Match the type of placode with its corresponding contribution:
Match the type of placode with its corresponding contribution:
The _____ is an area at the cephalic end of a vertebrate embryo where ectoderm and endoderm are not separated by mesoderm.
The _____ is an area at the cephalic end of a vertebrate embryo where ectoderm and endoderm are not separated by mesoderm.
Match the following anatomical features with their respective descriptions:
Match the following anatomical features with their respective descriptions:
What occurs during the invagination of the otic placode?
What occurs during the invagination of the otic placode?
The lateral edges of the otic pit move apart during its growth.
The lateral edges of the otic pit move apart during its growth.
Which type of embryonic cells first migrate through Hensen's node?
Which type of embryonic cells first migrate through Hensen's node?
The area opaca is the central translucent region of the blastoderm.
The area opaca is the central translucent region of the blastoderm.
At what point does the otic placode begin the invagination process?
At what point does the otic placode begin the invagination process?
In chick embryo development, cells that migrate anteriorly displace the _____ cells.
In chick embryo development, cells that migrate anteriorly displace the _____ cells.
Flashcards
Cleavage in Birds
Cleavage in Birds
The process of cell division in an embryo, which is discoidal and meroblastic in birds. It takes place in the blastodisc and involves equatorial and vertical cleavages, resulting in a 5-6 cell layer thick blastoderm.
What is the Area Pellucida?
What is the Area Pellucida?
The translucent central area of the blastoderm, where the embryo develops during avian development. It's known as the area pellucida.
What is the Primitive Streak?
What is the Primitive Streak?
A thickening of the epiblast at the posterior region of the embryo. It's formed by ingression of endodermal precursors from the epiblast and cell migration from the lateral region. It elongates towards the future head region and is thickest at the anterior end, known as Hensen's node. It defines the axis of the embryo.
What is the Primitive Groove?
What is the Primitive Groove?
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What is the Primitive Knot?
What is the Primitive Knot?
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What is the Primitive Pit?
What is the Primitive Pit?
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What is the Dynamic Nature of the Primitive Streak?
What is the Dynamic Nature of the Primitive Streak?
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What is Scatter Factor?
What is Scatter Factor?
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What cells migrate through Hensen's node first?
What cells migrate through Hensen's node first?
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What is the head process?
What is the head process?
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How do the cells migrating through the lateral primitive streak contribute to development?
How do the cells migrating through the lateral primitive streak contribute to development?
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What is the germinal crescent?
What is the germinal crescent?
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What is the endoderm?
What is the endoderm?
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What is the mesoderm?
What is the mesoderm?
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What is Hensen's pit?
What is Hensen's pit?
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What is the proamnion?
What is the proamnion?
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What is the Tegmentum?
What is the Tegmentum?
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What is the Cerebellum?
What is the Cerebellum?
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What is the Pons?
What is the Pons?
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What is the Cerebral Aqueduct?
What is the Cerebral Aqueduct?
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What is the Medulla Oblongata?
What is the Medulla Oblongata?
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What is the Fourth Ventricle?
What is the Fourth Ventricle?
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What are Rhombomeres?
What are Rhombomeres?
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What is the Epidermis?
What is the Epidermis?
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What are placodes?
What are placodes?
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What does the olfactory placode develop into?
What does the olfactory placode develop into?
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What does the lens placode develop into?
What does the lens placode develop into?
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What does the auditory placode develop into?
What does the auditory placode develop into?
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What is the otic placode?
What is the otic placode?
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What happens to the otic placode during development?
What happens to the otic placode during development?
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What happens to the otic pit as development progresses?
What happens to the otic pit as development progresses?
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Why is the otic pit formation important?
Why is the otic pit formation important?
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What does the paraxial mesoderm form?
What does the paraxial mesoderm form?
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What does the sclerotome form?
What does the sclerotome form?
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What does the myotome form?
What does the myotome form?
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What does the intermediate mesoderm form?
What does the intermediate mesoderm form?
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How is the lateral plate mesoderm divided?
How is the lateral plate mesoderm divided?
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What does the somatic layer of the lateral plate mesoderm form?
What does the somatic layer of the lateral plate mesoderm form?
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What does the splanchnic layer of the lateral plate mesoderm form?
What does the splanchnic layer of the lateral plate mesoderm form?
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What is the notochord and what is its fate?
What is the notochord and what is its fate?
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Heart Looping
Heart Looping
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Primitive Gut Tube
Primitive Gut Tube
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Foregut
Foregut
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Midgut
Midgut
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Hindgut
Hindgut
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Lung Buds
Lung Buds
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Liver Bud
Liver Bud
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Pancreas Bud
Pancreas Bud
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Study Notes
Chick Embryo Development
- Chick embryo development follows a structured timeline
- The provided outlines are for 18-hr, 24-hr, and 33-hr chick embryos
Chicken Egg Anatomy
- The egg white includes albumin layers: inner thin layer, outer thin layer, and a fibrous layer.
- The yolk is surrounded by the vitelline membrane, and the blastoderm is a thin layer of cells located on top of the yolk.
- The shell and the air space are also integral parts of the egg's anatomy.
- Chalazae are fibrous cords that hold the yolk in the center of the egg.
Cleavage in Birds
- Bird cleavage is discoidal meroblastic.
- Cleavage occurs in a blastodisc.
- Cleavage divides the blastoderm into smaller cells, forming a 5-6 layered structure.
Two-Layered Blastoderm
- A two-layered blastoderm is formed through ingression and delamination.
- The subgerminal cavity forms between the blastoderm and the yolk.
- The area pellucida is a translucent central region where the embryo develops.
- The area opaca is the peripheral, opaque area surrounding the area pellucida.
Primitive Streak
- The primitive streak defines the embryo's axis.
- It's a thickening of the epiblast in the posterior region of the embryo.
- The primitive streak is formed by the ingression of endodermal precursors and cell migration from the lateral region.
- It elongates toward the future head region, and its thickest point (Hensen's node) is at the anterior end.
- The primitive groove is a depression within the streak, allowing migrating cells to pass into the blastocoel.
- The primitive streak is analogous to the amphibian blastopore and includes the Hensen's node
Continuously Changing Cell Population
- Cells migrating through Hensen's node to the blastocoel, migrate to the anterior and form structures like foregut.
- Cells passing through the lateral parts of the primitive streak differentiate into endodermal and mesodermal tissues.
- The scatter factor, a 190kDa protein, facilitates EMT (epithelial-mesenchymal transition) during this process
Migration: Endoderm and Mesoderm Formation
- First cells migrating through Hensen's node are the pharyngeal endoderm.
- Cells in the germinal crescent are precursors for germ cells.
- Head mesenchyme and prechordal plate mesoderm do not migrate ventrally.
- The head process in the epiblast forms the anterior midline, including the chordamesoderm.
- Cells migrate inwardly through the lateral portions of the primitive streak to form endodermal and mesodermal tissues.
18-hr Chick Embryo
- The 18-hr chick embryo exhibits features marking the early stages of development.
Embryology of Chicken (18, 20 hours - Whole Mount)
- These stages detail the layout and features of those embryos
- Different structures like the proamnion, area opaca, area pellucida, neural plate, chord, Hensen's node, and primitive streak are identified according to the specifics of the stated hours and are visible in the corresponding labeled images.
24-hr Chick Embryo
- The embryo shows further development
- 4 pairs of somites are present and identifiable
- Area opaca is easily seen and so is the translucent area pellucida
- The primitive streak and neural groove are present along with Hensen's node
33-hr Chick Embryo
- The 33-hr chick embryo shows a more definite layout.
- Structures include forebrain, optic vesicle, midbrain, neural groove, notochord, mesoderm, area opaca, primitive groove, and more.
Fate of the Ectoderm
- The neuroectoderm forms the CNS and PNS
- The brain and spinal cord form from the neural tube
- Peripheral nervous system originates from the neural crest cells
- Sensory ganglia, autonomic ganglia, Schwann's cells, chromaffin cells, facial cartilage, and bone are derived from the neuroectoderm
Fate of the Surface Ectoderm
- Surface ectoderm forms the epidermis.
- Appendages such as hair, nails, and glands arise from the surface ectoderm.
- Mucous membranes lining the oral cavity, nasal cavity, and anus form from surface ectoderm; the lens and tympanic membrane are also derived from this tissue type.
Fate of Placodes
- Specialized areas in ectoderm, form specialized structures like the olfactory epithelium (olfactory placodes), lens of the eye, and inner ear structures, including the cochlea and vestibular system.
- The enamel of teeth, anterior pituitary gland, and the cornea also originate from ectoderm.
Fate of the Otic Placode
- The otic pit becomes well-formed and the invagination is complete by 33 hours
- Induction of the otic placode with thickening leads to formation in the rhombomeres region, and this placode differentiates from surrounding ectoderm.
- The process of invagination of the otic placode from 28-30 hrs leads to a cup-like structure forming the otic pit.
- The deepening and growth of the otic pit (30-33 hrs) with continuous proliferation within the pit and convergence of edges is a crucial part of development.
Fate of the Mesoderm
- Paraxial mesoderm develops into somites which in turn form sclerotome, myotome, and dermatome.
- Intermediate mesoderm forms the kidneys, gonads as well as parts of the genital ducts and adrenal glands (mesonephros).
- Lateral plate mesoderm separates into somatic and splanchnic layers to give rise to skeletal muscles, dermis, bone, lining of body cavities(peritonueum, pleura, pericardium), heart, blood vessels, smooth muscles of internal organs, and mesenteries to support organs.
- Notochord is a transient but crucial structure in signaling, patterning, eventually degenerating in most species but contributing to the intervertebral discs' nucleus pulposus.
Fate of the Heart
- Precardiac mesoderm forms a heart tube which contains endocardium (inner lining) and myocardium (muscle tissue).
- The development of the heart encompasses looping to establish the functional heart chambers
- The looping process that begins at 20 hours positions different heart segments
- This looping begins to develop into distinct chambers, including the atrium and ventricles in about 24-30 hours.
Fate of the Endoderm
- The endoderm forms the primitive gut tube, giving rise to the foregut, midgut and hindgut.
- Foregut forms the pharynx, esophagus, part of the stomach.
- Midgut forms the majority of the small intestine and the cecum.
- Hindgut forms the large intestine, the rectum, and the anus.
- Lung development begins as buds from the foregut, leading to bronchi and lungs. Liver and pancreas develop from the endoderm, with the liver from the ventral wall and the pancreas from the dorsal part.
- The thyroid gland development within the pharynx from endodermal tissue
- The parathyroid glands also arise from the endoderm's tissue located to the pharynx's regions.
- Urogenital system's epithelial lining also forms from endodermal tissue, including the parts of the urethra and bladder
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Description
Test your knowledge about embryonic development in birds with this quiz. Topics include types of cleavage, roles of various structures, and the formation of tissues during development. Perfect for students studying developmental biology or related fields.
