University:
Amherst College
Course:
BIOL 220 | Developmental Biologyl
Academic year:

2022
Views:

71

Pages:

12
Author:

Ashly Cantrell

Mesoderm II Heart: Migration of Splanchnic Mesenchyme Endocardium Lateral Mesoderm Fuses and Encircles Endocardium Heart Formation • Amphibians – – – – – forms in pharyngeal region splanchnic mesenchyme migrates aggregates to form central tube: endocardium fusion of lateral mesoderm (in ventral region) encirclement of endocardium (towards dorsal where layer fuses) Heart Formation • Formation of three layers – endocardium – myocardium – pericardium • Myocardium then adheres to endocardium to create the heart separated from pericardium by pericardial cavity (coelom) Heart Formation • So splanchnic mesoderm forms endocardium and myocardium • Somatic mesoderm forms pericardium • In higher vertebrates. two endocardial tubes form on each side and then fuse laterally Fusion of Endocardial Tubes Formation of Chick Heart Heart Formation 2 ventral aortae • Heart tube develops two bifurcations • Then twists and divides into chambers 2 vitelline veins Initial Heart Chambers Blood Vessels • A complicated and plastic system • Forms from – aggregation of mesechymal angioblasts into blood islands • peripheral region makes endothelial lining • central makes blood cells – or aggregation of angioblasts without blood cell formation • Vessels surrounded by basement lamina and smooth muscle Embryonic Blood Formation

Mesoderm II Part 1

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