Between the two limbs, and closely adjoining the splanchnopleure, is seen the heart. |
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. |
The yolk sac forms as the splanchnopleure surrounds the yolk. |
At the junction of somatopleure and splanchnopleure they are more rounded than elsewhere. |
The splanchnopleure and somatopleure are each composed of different structures. |