101 Questions
What is the primary driving force for embryonic development before implantation and development of the placenta?
Diffusion of oxygen and nutrients
When do the first blood and vascular elements appear in mammals?
End of the third week
Where do blood cells and blood vessels start to develop simultaneously?
Yolk sac and allantois
Why does the development of a functional embryonic circulatory system become essential for the embryo to survive?
To carry nutrients to all tissues and organs
What is the structure that initially forms from the dorsal wall of the atrium and progressively decreases in size as it grows downwards?
Septum primum
During prenatal life, what causes blood to flow from the right atrium to the left atrium through the foramen ovale?
Increased pressure in the right atrium
What prevents blood flow in the opposite direction through the foramen ovale?
Septum secundum
Which structure acts as a valve to preclude the flow of blood between both atria after birth?
Septum primum
What completes the proper closure of the interventricular septum?
Membranous part
What is formed when two subendocardial swellings merge to create a spiral septum?
Aorticopulmonary septum
What divides the common canal into the left and right atrioventricular openings?
Septum intermedium
'The valves are attached to the bottom of the ventricular wall by tendinous chords and papillary muscles.' What structures are being referred to in this statement?
Atrioventricular valves
'The endocardial cushions will be transformed into the atrioventricular valves.' What gives rise to these valves?
Endocardial cushions
'A variety of congenital defects may result from improper valve sculpturing.' What causes these defects?
'Endocardial cushions'
What structure divides the bulbus cordis and adjacent truncus arteriosus?
Spiral Septum
What provides temporary communication between right and left atria during prenatal life?
Foramen Ovale
What type of vessels transport blood away from the heart under high pressure?
Arteries
What is the process responsible for expanding and remodeling existing vascular networks?
Angiogenesis
Which type of vessel has valves to prevent backflow?
Veins
What is the first functional organ in vertebrate embryos?
Heart
What are the distinct layers of arteries?
Intima, media, adventitia
What type of vessel facilitates exchange of substances between the blood and extracellular fluid?
Capillaries
What do arteries and veins have based on their roles in transporting blood under varying pressure conditions?
Distinct wall structures and functions
What is the process of formation of endothelial tubes that eventually become the heart?
Cardiogenesis
What is composed of the cardiac endocardium, myocardium, and epicardium?
The heart
What are the first blood vessels formed through?
Vasculogenesis and angiogenesis
What type of vessels transport blood towards the heart under low pressure?
Veins
What are thin-walled vessels that transport blood towards the heart under low pressure?
Pulmonary veins
During embryonic development, what is the first visible sign of right-left asymmetry?
Cardiac looping
What is the function of the bulbus cordis in the primitive heart tube?
It is destined to become the right ventricle
What is the significance of upstream signalling pathways in embryonic heart development?
They impose asymmetry onto a bilaterally symmetric body plan
What does situs inversus refer to?
A mirror image of a normal body and organ locations
Which part of the tubular heart becomes the left ventricle?
Primitive ventricle
What is the main function of the primitive atrium in the tubular heart?
Receives blood and pumps it to the ventricle
In which order do the expanded portions of the cardiac tube develop from caudo-cranial direction?
Sinus venosus, Atrium, Ventricle, Bulbus cordis, Truncus arteriosus
What is the purpose of developing septa in the primary atrium, ventricle and bulbus cordis?
Creation of right and left atria and ventricles
What major structural changes occur to allow terrestrial animals to transition from prenatal circulation to postnatal circulation?
Complete separation of pulmonary and systematic circulations
Where does the first extra-embryonic haematopoietic period take place?
In the yolk sac during the first third of embryonic development
What is the process of de novo formation of blood vessels from endothelial progenitor cells called?
Vasculogenesis
During which period does haematopoiesis move to the liver and spleen?
Hepatolienal period
What are the earliest blood cells produced during haematopoiesis?
Primitive erythrocytes
Where does haematopoietic activity occur in the postnatal period?
Spleen and bone marrow
What role does angiogenesis play in blood vessel formation?
Growth of new blood vessels from pre-existing vessels
Where do pluripotent stem cells colonise during the hepatolienal period?
Liver
What is the primary site for haematopoietic activity in the last third of pregnancy?
Bone marrow
Where do blood vessels form through either vasculogenesis or angiogenesis?
Yolk sac and allantois
What is the primary function of the bulbus cordis in the primitive heart tube?
To pump blood to the lungs
During prenatal life, what causes blood to flow from the right atrium to the left atrium through the foramen ovale?
Higher pressure in the right atrium
What completes the proper closure of the interventricular septum?
Growth of the endocardial cushions
What are the distinct layers of arteries?
Endothelium, subendothelial layer, media, and adventitia
Which structure marks the beginning of heart development as a C-shaped loop?
Bulbus cordis
What is the primary driving force for embryonic development before implantation and development of the placenta?
Nutrient uptake
During which period does haematopoiesis move to the liver and spleen?
Hepatolienal period
What does situs inversus refer to?
Reversal of the normal positions of thoracic and abdominal organs
What role does angiogenesis play in blood vessel formation?
Formation of new blood vessels from endothelial progenitor cells
Where do blood cells and blood vessels start to develop simultaneously?
Extra-embryonic mesoderm
What is the first functional organ in vertebrate embryos?
Heart
What provides temporary communication between right and left atria during prenatal life?
Foramen ovale
When do the first blood and vascular elements appear in mammals?
During embryonic development
What type of vessels transport blood away from the heart under high pressure?
Arteries
What is the purpose of developing septa in the primary atrium, ventricle, and bulbus cordis?
To prevent mixing of oxygenated and deoxygenated blood
What is formed when two subendocardial swellings merge to create a spiral septum?
Interventricular septum
Where does the first extra-embryonic haematopoietic period take place?
In the yolk sac during the first third of embryonic development
What are the earliest blood cells produced during haematopoiesis?
Primitive erythrocytes
Where does haematopoietic activity occur in the postnatal period?
Bone marrow and lymph nodes
What is the process of de novo formation of blood vessels from endothelial progenitor cells called?
Vasculogenesis
What is the primary site for haematopoietic activity in the last third of pregnancy?
Bone marrow
What type of vessels transport blood towards the heart under low pressure?
Veins
What is the purpose of developing septa in the primary atrium, ventricle, and bulbus cordis?
To prevent mixing of oxygenated and deoxygenated blood
What are thin-walled vessels that transport blood towards the heart under low pressure?
Veins
What role does angiogenesis play in blood vessel formation?
Forms new blood vessels from pre-existing vessels
Where do pluripotent stem cells colonise during the hepatolienal period?
Liver
What is formed when two subendocardial swellings merge to create a spiral septum?
Interventricular septum
What type of vessels transport blood away from the heart under high pressure?
Arteries
What is the process responsible for expanding and remodeling existing vascular networks?
Angiogenesis
What are thin-walled vessels that transport blood towards the heart under low pressure?
Veins
What is the first functional organ in vertebrate embryos?
Heart
What are the distinct layers found in arteries?
Tunica intima, tunica media, tunica externa
What are the single-layer vessels that facilitate exchange of substances between the blood and extracellular fluid?
Capillaries
What is the correct term for the de novo formation of blood vessels from endothelial progenitor cells?
Angiogenesis
What structure forms when endothelial tubes join together to create a single, pumping organ?
Heart
What are the vessels defined by their direction of blood flow and specific anatomical and functional features?
Arteries
What is the term used for the formation of the first blood vessels through a process called vasculogenesis and angiogenesis?
Vasculogenesis
What do arteries have to prevent backflow of blood?
Nothing, they rely on gravity
What is the term used for the process of forming new blood vessels from pre-existing ones?
Angiogenesis
During prenatal life, what causes blood to flow from the right atrium to the left atrium through the foramen ovale?
Pressure difference between the right and left atria
What is the main function of the primitive atrium in the tubular heart?
Temporary communication between right and left atria
What prevents blood flow in the opposite direction through the foramen ovale?
Septum primum
What are thin-walled vessels that transport blood towards the heart under low pressure?
Veins
What is composed of the cardiac endocardium, myocardium, and epicardium?
Heart wall
What is formed when two subendocardial swellings merge to create a spiral septum?
Spiral septum (aorticopulmonary septum)
What type of vessels transport blood away from the heart under high pressure?
Arteries
'The endocardial cushions will be transformed into the atrioventricular valves.' What gives rise to these valves?
'Atrioventricular canal'
'The valves are attached to the bottom of the ventricular wall by tendinous chords and papillary muscles.' What structures are being referred to in this statement?
'Atrioventricular valves'
What completes the proper closure of the interventricular septum?
Membranous part of interventricular septum
Where do blood cells and blood vessels start to develop simultaneously?
Bulbus cordis and truncus arteriosus
What type of vessels transport blood away from the heart under high pressure?
Arteries
What is the primary cause of Ectopia Cordis?
Abnormal positioning of the heart due to interference in the normal descent
What may result from a patent foramen ovale?
Cyanosis and polycythaemia
What is the consequence of atrial septal defects in postnatal circulation?
Serious disturbances in the postnatal circulation
What is the result of a failure in the closure of the foramen ovale?
Disturbances in postnatal circulation
Study Notes
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Angiogenesis is a process responsible for expanding and remodeling existing vascular networks, important for growth, development, and tissue repair.
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First blood vessels, called capillaries, are formed through a process called vasculogenesis and angiogenesis.
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Arteries are thick-walled vessels that transport blood away from the heart under high pressure, with three distinct layers: intima, media, and adventitia.
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Capillaries are single-layer vessels that facilitate exchange of substances between the blood and extracellular fluid.
-
Veins are thin-walled vessels that transport blood towards the heart under low pressure, and have valves to prevent backflow.
-
Arteries and veins are defined by their direction of blood flow and resulting specific anatomical and functional features.
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The heart is the first functional organ in vertebrate embryos and beats spontaneously by certain developmental stages.
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Heart development begins with the formation of endothelial tubes, which eventually become the heart, and are joined together to form a single, pumping organ.
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The heart is composed of the cardiac endocardium, myocardium, and epicardium, each with distinct functions.
-
Arteries and veins have distinct wall structures and functions based on their roles in transporting blood under varying pressure conditions.
-
Haematopoiesis is the process of blood cell formation from pluripotent stem cells.
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First extra-embryonic haematopoietic period, the mesoblastic period, takes place in the yolk sac during the first third of embryonic development.
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Blood islands in the yolk sac walls form from haemangioblasts, which are multipotent precursor cells that can differentiate into both blood cells and blood vessels.
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Hematopoietic stem cells (HSCs) form in the centre of the blood islands, and the first blood cells produced are primitive red blood cells (primitive erythrocytes).
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During the middle third of pregnancy, haematopoiesis moves to the liver and spleen, forming nucleus-free erythrocytes and the first leukocytes and thrombocytes.
-
The final haematopoietic period occurs in the last third of pregnancy, with haematopoietic activity located in the bone marrow, lymph nodes, thymus, and spleen.
-
In the postnatal period, bone marrow produces all red blood cells and 60–70% of white cells, while lymphatic tissues produce lymphocytes, and reticuloendothelial tissues produce monocytes.
-
Pluripotent stem cells colonise the liver during the hepatolienal period.
-
The earliest stage of hematopoiesis takes place in the blood islands of the yolk sac, and blood vessels form through either vasculogenesis or angiogenesis.
-
Vasculogenesis is the de novo formation of blood vessels from endothelial progenitor cells, and it plays a role in the formation of the first blood vessels in the yolk sac and allantois.
-
Angiogenesis is the growth of new blood vessels from pre-existing vessels, and it is a lifelong process.
-
The vascularisation of the foetal membranes is a result of local formation of new capillaries in the yolk sac and allantois, rather than protrusion of embryonic vessels into the placenta.
-
Haematopoiesis is the process of blood cell formation from pluripotent stem cells.
-
First extra-embryonic haematopoietic period, the mesoblastic period, takes place in the yolk sac during the first third of embryonic development.
-
Blood islands in the yolk sac walls form from haemangioblasts, which are multipotent precursor cells that can differentiate into both blood cells and blood vessels.
-
Hematopoietic stem cells (HSCs) form in the centre of the blood islands, and the first blood cells produced are primitive red blood cells (primitive erythrocytes).
-
During the middle third of pregnancy, haematopoiesis moves to the liver and spleen, forming nucleus-free erythrocytes and the first leukocytes and thrombocytes.
-
The final haematopoietic period occurs in the last third of pregnancy, with haematopoietic activity located in the bone marrow, lymph nodes, thymus, and spleen.
-
In the postnatal period, bone marrow produces all red blood cells and 60–70% of white cells, while lymphatic tissues produce lymphocytes, and reticuloendothelial tissues produce monocytes.
-
Pluripotent stem cells colonise the liver during the hepatolienal period.
-
The earliest stage of hematopoiesis takes place in the blood islands of the yolk sac, and blood vessels form through either vasculogenesis or angiogenesis.
-
Vasculogenesis is the de novo formation of blood vessels from endothelial progenitor cells, and it plays a role in the formation of the first blood vessels in the yolk sac and allantois.
-
Angiogenesis is the growth of new blood vessels from pre-existing vessels, and it is a lifelong process.
-
The vascularisation of the foetal membranes is a result of local formation of new capillaries in the yolk sac and allantois, rather than protrusion of embryonic vessels into the placenta.
-
Atrium partition: Septum primum, a membranous tissue, grows from the ceiling of the atrium, dividing it into left and right halves.
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A strong muscular septum secundum grows immediately to the right of septum primum, gradually overlapping the foramen secundum during fetal development.
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An incomplete partition of the atrium by the septum secundum forms the foramen ovale, allowing temporary communication between the right and left atria during prenatal life.
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The remaining portion of the septum primum acts as the valve of the foramen ovale, preventing blood flow from the left atrium into the right atrium after birth.
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The two septa fuse to form the final inter-atrial septum, but a remnant of the foramen ovale remains as an indentation in the wall of the right atrium, the fossa ovalis.
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Ventricle partition: The primordial interventricular septum is a muscular ridge that forms early in development, dividing the ventricle into left and right halves.
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A temporary interventricular foramen exists between the free edge of the interventricular septum and the endocardial cushions, which is closed by the membranous part of the interventricular septum.
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The endocardial cushions grow and fuse in the midline to form the septum intermedium, dividing the primary atrioventricular channel into the left and right atrioventricular openings.
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The left and right atrioventricular valves are formed from mesenchyme of the endocardial cushions, with the left valve having two flaps (bicuspid or mitral valves) and the right valve having three flaps (tricuspid valves).
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The partitioning of the atrium and ventricle also affects the atrioventricular canal, with endocardial cushions fusing to form the septum intermedium and divide the common canal into the left and right atrioventricular openings.
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The bulbus cordis and truncus arteriosus are the origins of the left and right halves of the ventricle, respectively, and are gradually separated by an interventricular septum.
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The bulbar ridges, subendocardial swellings along the lumen of the bulbus cordis, grow inwardly and merge to form the spiral septum (aorticopulmonary septum), dividing the bulbus cordis and truncus arteriosus into the aortic trunk and pulmonary trunk.
Test your knowledge about angiogenesis, the process responsible for remodelling and expanding vascular networks, and its role in growth, development, wound healing, and cancer progression.
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