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Title: The morphogenesis of feather primordia in chicken skin
Author: Davidson, Duncan Ross
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1978
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This thesis examines aspects of two broad problems; first, what governs the time and position at which organs form; second, how do cells build organ primordia? These problems have been investigated in six-day chicken dorsal skin. To facilitate microscopic observation, skin was cultured on transparent collagen. Regarding the first problem, patterns formed by feathers in cultured skin are determined, in part, by interaction between adjacent sites shortly before primordium morphogenesis. Histology of fresh skin confirmed that arrays of dermal cells extend from morphologically distinct sites towards new ones, but cutting skin before morphogenesis did not prevent normal pattern development; thus extension of cell patterns does not define the feather pattern. Fused primordia sometimes formed in culture, suggesting that primordia are not spaced by steric interaction. Thus spacing appears not to depend on dermal morphogenesis. Pre-existing organisation also influences the pattern. Development of cut skin showed that the time of morphogenesis is preset over most of the dorsal skin before any primordia form. The actual pattern differs, at morphogenesis, from a simple packing pattern: this, and other evidence, suggests that pre-existing dermal organisation helps determine primordium position. Regarding the second problem, the development of condensed dermis in primordia was studied. Quantitative analysis showed that proliferation cannot account for the increase in cell numbers in condensations in culture. Histology of fresh skin, and filming, suggested that cells do not migrate into condensations along arrays. Short-range centripetal movement is suggested. Experiments using colcemid showed that neither proliferation nor migration are essential for changes in primordium shape up to the feather-bud stage. Dissection experiments showed that dermal cells adhere more strongly to the basement membrane in primordia than elsewhere. These results suggest that changes in con properties (possibly adhesiveness and contractility) at the primordium site are responsible for condensation morphogenesis and stability. Similarities with other organ primordia are emphasised.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available