PMID: 16612976Apr 15, 2006Paper

Fine structure of juvenile feathers of the zebrafinch in relation to the evolution and diversification of pennaceous feathers

Journal of Submicroscopic Cytology and Pathology
Lorenzo Alibardi

Abstract

The present ultrastructural study describes the formation of feather ramification in developing juvenile feathers of the zebrafinch, a small passeraceous bird. The study stresses the importance of the detailed knowledge on the cell structure of barb ridges for the understanding of feather development and evolution. Feather formation depends on the morphogenesis of long barb ridges, in which cells are displaced into lateral barbule plates and a medial barb cells region. These cells merge into long chains and form a syncitium organized in a ramified structure that preserves the original cell disposition within the barb ridge. Barb vane ridge cells surround barb and barbule cells. Barbules separate after the degeneration of barb vane ridge cells. In barbule cells the formation of hooklets resembles the process of formation of climbing setae of digital pads of some lizards. The cytoplasm of barb vane ridge cells is localized among tile-like overlapped barbule cells that form barbule chains, and maintains a serrated outline. When barb vane ridge cells degenerate among keratinized barbules, keratinized hooklets remain. Hooklets allow the ordered grasping of barbules to form a close and planar vane of feathers. The rachis of juvenile ...Continue Reading

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