title: Morphology of the distal tip of the upper mandible of the ostrich (Struthio camelus) embryo during hatching.
abstract: 1. The morphology of the distal part of the upper mandible in ostrich embryos was investigated using scanning electron microscopy just prior to and during hatching. 2. Although a keel-like structure on the tip of the upper mandible superficially resembles an egg tooth it appears to play no role during hatching. 3. The distal tip of the upper mandible is covered by an amorphous layer, the right side of which disappears during the hatching process. This layer acts to protect the beak during the rubbing process which creates a hole in the inner shell membrane during hatching.
authors.affiliation: Department of Anatomy and Developmental Biology, St George's Hospital Medical School, London, England.
authors.forename: M K
authors.initials: MK
authors.lastname: Richardson
authors.forename: D C
authors.initials: DC
authors.lastname: Deeming
authors.forename: C
authors.initials: C
authors.lastname: Cope
mesh_terms: D000818:Animals; D004528:Egg Shell; D008334:Mandible / Q000196:embryology* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D020310:Struthioniformes / Q000196:embryology*