Soluble CD23 binds to CD21 on the surface of IgE synthesizing B cells, IgE synthesis is increased.

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#Id: 1589

#Unit 5. Developmental Biology

Primitive Groove

A depression that forms within the primitive streak that serves as an opening through which migrating cells pass into the deep layers of the embryo.

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#Id: 1590

#Unit 5. Developmental Biology

Primitive groove is homologous to the amphibian blastopore

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#Id: 1591

#Unit 5. Developmental Biology

Hensen’s node (Primitive Knot)

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#Id: 1592

#Unit 5. Developmental Biology

A regional thickening of cells at the anterior end of the primitive streak

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#Id: 1593

#Unit 5. Developmental Biology

Hensen’s node is the functional equivalent of the organizer (dorsal lip of the amphibian blastopore)

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#Id: 1594

#Unit 5. Developmental Biology

Primitive Pit 

A funnel-shaped depression at the center of Hensen’s node through which cells migrate to form the notochord and prechordal plate.