Determine the type of formation of the third germ layer:
1) The cells of the mesoderm are formed by a series of successive divisions of two cells (teloblasts), symmetrically located in the cavity of the blastocoel in the region of the lips of the blastopore.
2) The cellular material of the future mesoderm is initially part of the wall of the primary intestine. Later, the mesoderm stands out as an independent anlage, by symmetrical invagination into the blastocoel cavity, followed by lacing.
1) Teloblastic 2) Enterocoelous.
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