Primitive pit

Primitive pit
Surface view of embryo of Hylobates concolor. The amnion has been opened to expose the embryonic disk. (Primitive pit not labeled, but region is visible.)
*Anatomical terminology* [edit on Wikidata]

The primitive pit is a depression in the center of the primitive knot, connecting to the notochord. It consists of part of the primitive streak.

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

Human embryogenesis in the first three weeks

Week 1

Week 2
(Bilaminar)

Germ layers	Archenteron/Primitive streak Primitive pit Primitive knot/Blastopore Primitive groove Gastrula Gastrulation Regional specification Embryonic disc

Ectoderm	Surface ectoderm Neuroectoderm Somatopleuric mesenchyme Neurulation Neural crest

Endoderm	Splanchnopleuric mesenchyme

Mesoderm	Axial mesoderm Paraxial Somite Somitomere Intermediate Lateral plate Intraembryonic coelom Splanchnopleuric mesenchyme Somatopleuric mesenchyme

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