مراحل تكوين الجنين Amphioxus embryonic development

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Amphioxus embryonic development: Ovum,fertilization, Morula,Blastula, Gastrula: • The egg of amphioxus is isolecithal and thecleavage is of holoblastic type. About one hour after fertilization, the egg is divided into 2 blastomeres.The plane of this first cleavage is passing through the egg axis from pole to pole.Next, the cleavage is in a vertical plane, but at right angles to the first plane.In the third series of division, the planes of separation are horizontal. By the 16 to 32-cell stage, the cells are crowded together into a compact mass within the zona pellucida. The embryo is now known as morula.Soon the balstomeres arrange themselves in a circular manner forming a blastula around a central space, the blastocoel. This marks the end of the cleavage period. • Amphioxus embryonic development مراحل تكوين الجنين • • مراحل تكوين الجنين Amphioxus embryoni... • Amphioxus embryonic development مراحل تكوين الجنين • • مراحل تكوين الجنين Amphioxus embryoni...

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