Lectures - heart and circulatory system formation

heart formation is an example of

organogenesis

in chickens, when is the 1st heartbeats found

33-38 hours post fertilization

in chickens when is circulation well established

51-56 hours post fertilization

when does heart formation occur

prior to body folding, starts during primitive streak regression

what mesoderm starts the chain to give rise to precardiac cells

splanchnic mesoderm

what happens to splanchnic mesoderm cells during primitive streak regression in terms of heart formation

splanchnic meso cells migrate ventrally and merge anteriorly to form a left and right primary heart field region (HFR) via det + diff

what happens to HFR cells after its separation from splanchnic meso

HFR cells undergo det + diff and push and shove around anterior embryo to form cardiac crescent

as embryo folding begins, what is interrelated

heart, foregut, coelom, and ventral body wall

what forms at the same time as splanchnic mesoderm migration

foregut

at the same time as foregut formation what happens to cardiac crescent cells

they begin to differentiate into 2 types of cells

what do cardiac crescent cells (precardiogenic cells) det + diff into

myocardial and endocardial precursor cells

what do endocardial precursor cells do

form endocardial tubes like blood vessels starting with aorta and pulmonary artery

as the foregut closes into gut tube, what happens in the heart

myocardial precursors are pulled ventrally and meet at midline

when the myocardial precursors meet at midline, what happens to them

endocardial tubes and myocardial precursors fuse to form simple cardiac tube

does apoptosis occur in heart formation

yes, when the endocardial tubes meet at the midline they undergo apoptosis during cardiac tube formation

what occurs after the simple cardiac tube formation

differentiation into cardiac fibers begins

when looking at a simple cardiac tube, what is posterior that should be anterior

atria

describe the process of heart looping

heart tube grows and bends to squash on itself, R+L atria fold up and septation occurs

once regions are in correct spots, walls begin to form

describe the heart forms of heart looping

straight tube → initial loop → C shaped → S shaped → final heart + chamber formation

summarize the process of heart formation to the creation of myocardial + endocardial precursors

splanchnic meso → HFR cells → cardiac crescent cells (aka precardiogenic cells) → myocardial + endocardial precursors