Embryo folding video
Shortly after the formation of the intraembryonic mesoderm, the embryo folds laterally and anteroposteriorly in order to reduce the size of the gut formed from the yolk sac. And also to place the intraembryonic mesoderm ventrally.
Embryo folding. The flat trilaminar embryonic disc progressively increases in size and undergoes folding to be transformed into cylindrical structure. Embryo folding takes place in two planes- longitudinal folding and transverse folding. These foldings take place in a vertical direct during longitudinal fold and the head fold and the tail fold are formed. As the head fold forms part of yolk sac is incorporated into the embryo from the primitive foregut. This primitive foregut is formed separated from the stomatodaeum by the oropharyngeal membrane, the cardiogenic area together with the primitive heart tubes and the septum transversum. They come to lie ventral to the primitive foregut with the septum transversum lying caudal to the primitive heart. The septum transversum takes part in the formation of the diaphragm. As the tail fold forms part of the secondary yolk sac is incorporated into the embryo as the primitive hind gut. This primitive hind gut is separated from the cloaca by the cloacal membrane. During transverse folding part of secondary yolk sac is also incorporated into the embryo as the primitive hind gut. This primitive hind gut is separated from the cloaca by the cloacal membrane during transverse folding. Part of the secondary yolk sac is also incorporated into the embryo as the primitive midgut. And as this midgut forms it becomes attached to the dorsal aspect of the embryo by the dorsal mesentery. As a result a result of transverse and longitudinal folding the embryo becomes attached ventrally with the main part of the secondary yolk sac. The yolk sac and the connecting stalk-all are formed and they lie close and ventral. Together they take part in the formation of the umbilical cord.
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Creator: Oluwole Ogunranti