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Hamburger and Hamilton Stage 21

HH21 (3.5 days).
43-44 somites; extreme tip of tail unsegmented.
Proximo-distal axes of wing and leg directed caudally.
Posterior contours of wing and leg buds meet the baseline at an angle of c.90 degree.
L/W of wing = 2.3-2.7; leg = 2.0-2.5.
The posterior curvature includes lumbo-sacral region.
Maxillary process definitely longer than mandibular, extending approx. to middle of eye.
2nd arch overlaps 3rd ventrally.
4th arch distinct; 4th cleft visible as a slit.
Eye pigmentation: faint.

Ontology

  1. TXT - Text Format
    The ABSTRACT ONTOLOGY (NOT Staged/Timed) with all pathways to child nodes materialised, in Plain Text only, as a Tree Report.

  2. OBO - OBO Format
    The ABSTRACT ONTOLOGY (NOT Staged/Timed) in OBO Flat File Format, version 1.2, available for viewing/editing using OBO-Edit.

References

  1. H. Eyal-Giladi and S. Kochav
    From cleavage to primitive streak formation: A complementary normal table and a new look at the first stages of the development of the chick : I. General morphology
    Developmental Biology, Volume 49, Issue 2, April 1976, Pages 321-337

  2. V. Hamburger and H.L. Hamilton
    A series of normal stages in the development of the chick embryo
    Journal of Morphology, 1951, Volume 88, Pages 49-92 (reprinted in Developmental Dynamics, December 1992, Volume 195, Issue 4, pages 231-72)

  3. R. Bellairs and M. Osmond
    The Atlas of Chick Development
    Academic Press, ISBN 0-12-084790-6, 1998

  4. C.D. Stern and P.W.H. Holland (Ed.s)
    Essential Developmental Biology: A Practical Approach
    Oxford University Press, ISBN 0-19-963423-8, 1993

  5. M.A.J. Selleck and C.D. Stern
    Fate mapping and cell lineage analysis of Hensen's node in the chick embryo
    Development, Volume 112, Pages 615-626, 1991