File:Streeter1957 stage 21 plate01.jpg

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Plate 1. Photographs of three embryos belonging to horizon xxi

The superficial head plexus is plainly visible in embryos of this age group, and has spread to a level more than half the distance between the eye-ear plane and the vertex of the head. The fingers are longer and show an early stage in the development of touch pads. The hands are flexed at the wrists and are approaching each other over the heart region. The lower extremeties curve towards the median plane, and toes of the two feet make contact in some specimens. x3.

Figs. 54-56. No. 4090.

Figs. 57-59. No. 8553.

Figs. 60-62. No. 7392.

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Links: 1 Graph Embryos 11-23 | 4 Eye and optic nerve 19-23 | Plate 1 - Cornea | Plate 2 - Hypophysis


Streeter GL. Developmental Horizons In Human Embryos Description Or Age Groups XIX, XX, XXI, XXII, And XXIII, Being The Fifth Issue Of A Survey Of The Carnegie Collection. (1957) Carnegie Instn. Wash. Publ. 611, Contrib. Embryol., 36: 167-196.

Cite this page: Hill, M.A. (2024, April 13) Embryology Streeter1957 stage 21 plate01.jpg. Retrieved from

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