Acta Zoologica Cracoviensia, 30() 1987
The principal structure of the avian egg-shell: data of SEM studies
Abstract:
The egg-shell structure of 5 species of Ratitae and 13 species of Neognathae was studied using SEM. The results confirm the value of considering the regularities of egg-shell formation from the point of biomineralization. The growth of crystals in the egg-shells is induced and controlled by the organic matrices, which act as templates. The vertical macro-units of egg-shell growth (cone + column) are of polycrystalline structure and represent the system of hierarchically coordinated blocks of various size levels. Crystallites of all levels possess a “sheath”, composed of organic sheets, which if chemically destroyed, can result in the consecutive decomposition of prisms and wedges into structural elements. The complex arrangement of egg shell growth units is caused by biologically predetermined polysynthetic twinning of submicroscopic plate crystallites. The results confirm Erben´s (1970) data on the distinctions in the structure of Ratitae and Neognathae egg-shells. Some peculiar characteristics in the egg-shells of Passeriformes were found.
