| Popis: |
The main source of epicardium in birds is proepicardium, which is situated on the right horn of the sinus venous, dorsally to atrio-ventricular groove. Recently one more source of epicardium was described, it was named pericardial proliferates, that give rise to the epicardium of the distal part of the outflow tract. But, after proepicardium photoablation, compensatory epicardium aroused from the ventral body wall, caudally to the heart. Thereby the goal of our work was to investigate proepicardium-like structures of the pericardial cavity in birds. Beginning from the 13 stage by HH we observed proepicardium-like structures, which in cellular composition were similar to proepicardium. They derived from the lateral plate mesoderm and were situated on the funnel of the anterior intestinal gate, along to one of the vitelline vein. On the 16/17 stage by HH vesicles, containing mesenchimal cells, was budding of from proepicardium-like structures and attached to the heart on the right side of atrio-ventricular groove and ventricular loop. Localization of the proepicardium-like structures in the place, where in mammalian septum transversum (the source of proepicardium in mammalian) forms, and also the possibility of proepicardium-like structures to form vesicles gave us an occasion to suggest, that proepicardium-like structures are homologous of mammalian proepicardium. It could be concluded only after further investigations. |
