Development of the heart
1. Processes of embryonic heart development:
- The vascular system appears in the middle of the third week.
- Progenitor heart cells lie in the epiblast, they migrate through the streak and into the
visceral layer of lateral plate mesoderm where some form a horseshoe-shaped
cluster of cells called the primary heart field (PHF)
- These cells form portions of the atria and the entire left ventricle. The right ventricle
and outflow tract (conus cordis and truncus arteriosus) are derived from the
secondary heart field (SHF).
-Initially, the cardiogenic area is anterior to the oropharyngeal membrane, with closure of
the neural tube and formation of the brain vesicles, the central nervous system grows
cranially so rapidly that it extends over the central cardiogenic region.
-Induction of the cardiogenic region is initiated by anterior endoderm underlying progenitor
heart cells and causes the cells to become myoblasts and vessels. BMPs secreted by this
endoderm in combination with inhibition of WNT expression induces expression ofNKX2.5,
the master gene for heart development.
-By the 22nd day of development, lateral body wall folds bring the two sides of the
horseshoe toward the midline where they fuse (except for their caudal [atrial] ends) to form
a single, slightly bent heart tube consisting of an inner endocardial tube and a surrounding
myocardial mantle.
1. Processes of embryonic heart development:
- The vascular system appears in the middle of the third week.
- Progenitor heart cells lie in the epiblast, they migrate through the streak and into the
visceral layer of lateral plate mesoderm where some form a horseshoe-shaped
cluster of cells called the primary heart field (PHF)
- These cells form portions of the atria and the entire left ventricle. The right ventricle
and outflow tract (conus cordis and truncus arteriosus) are derived from the
secondary heart field (SHF).
-Initially, the cardiogenic area is anterior to the oropharyngeal membrane, with closure of
the neural tube and formation of the brain vesicles, the central nervous system grows
cranially so rapidly that it extends over the central cardiogenic region.
-Induction of the cardiogenic region is initiated by anterior endoderm underlying progenitor
heart cells and causes the cells to become myoblasts and vessels. BMPs secreted by this
endoderm in combination with inhibition of WNT expression induces expression ofNKX2.5,
the master gene for heart development.
-By the 22nd day of development, lateral body wall folds bring the two sides of the
horseshoe toward the midline where they fuse (except for their caudal [atrial] ends) to form
a single, slightly bent heart tube consisting of an inner endocardial tube and a surrounding
myocardial mantle.
