The splanchnopleure also envelops it, so that, morphologically speaking, the yolk lies within the mesenteron.
The heart is undoubtedly formed out of the mesoblast of the splanchnopleure only.
Between the two limbs, and closely adjoining the splanchnopleure, is seen the heart (ht).
At the junction of somatopleure and splanchnopleure they are more rounded than elsewhere.
It shews the formation of the heart (ht) as a cavity between the splanchnopleure and the wall of the throat.
splanchnopleure splanch·no·pleure (splāngk'nə-plur')
A layer of embryonic cells formed by association of part of the mesoderm with the endoderm and developing into the wall of the viscera.