ISSN:
1573-6865
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Following excision of the posterior half of the three-day chick wing bud, the anterior half which normally forms humerus (part), radius and digit 2, forms only a single skeletal element (humerus, of humerus fused with reduced radius). If part of the zone of polarizing activity is included in the remaining anterior part of the wing bud, a normal wing with normal skeleton forms. Excision of the anterior half of the chick wing-bud results in the posterior half forming humerus (part), ulna and digits 3–5. This is confirmed as the normal prospective fate of the posterior half by chimeric quail-chick wing-buds in which Feulgen staining of the nucleolus-associated heterochromatin of quail cells enables their contribution to the resultant skeleton to be identified. Beginning at 18 h alter posterior half amputation, the anterior distal mesenchyme becomes necrotic and the apical e todernal ridge regresses. By contrast, following anterior half amputation, posterior halves develop no more cell death than control wing-buds. Anterior half regression is characterized by cell fragmentation and phagocytosis. First, in both the apical ectodermal ridge and distal mesenchyme cells, acid phosphatase-rich autophagic bodies appear, the cells then becoming autolytic (with diffuse acid phosphatase activity) and fragmenting. Neighbouring cells phagocytose the dead cell fragments, the mesenchyme cells forming large ‘non-professional’ macrophages containing many acid phosphatase-rich vacuoles. These experiments show that for survival and differentiation, the anterior and distal mesenchyme of the wing bud requires a factor from the posterior part, thus suggesting that the zone of polarizing activity controlsantero-posterior differentiation in the normal wing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01002716
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