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Stage 7 embryos are in the presomite period with a well-defined embryonic disc. They have an estimated postfertilization age of approximately 18 to 21 days and a greatest length of 0.6 mm. The embryonic disc is symmetrical and slightly convex in the plane of its longitudinal axis. The gastrulation (primitive) node and notochordal process can be identified.


Section 36

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Section 44-2-2

Section 44-2-2

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