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Regulation of avian eggshell porosity
Author(s) -
Tullett S. G.
Publication year - 1975
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1975.tb02237.x
Subject(s) - eggshell , coturnix coturnix , quail , biology , porosity , calcite , shell (structure) , anatomy , mineralogy , materials science , ecology , paleontology , chemistry , composite material
Pores and mammillae per unit area of the eggshells of 34 avian species were counted. The number of pores/cm 2 varied from about 45 for the King penguin ( Aptenodytes patagonia ) to 306 for the Japanese quail ( Coturnix coturnix ). Throughout this range there was a positive linear correlation ( r =0.92) between the number of pores and the number of mammillae per unit area of shell. Scanning electron micrographs of the inner surface of eggshells scoured with NaOH suggested that the above relationship may result from the packing of the calcite columns, which is controlled by the density of the mammillary seeding sites laid down upon the outer shell membrane. Thus it is inferred that the distribution in the uterus of the cells which secrete the sites on which calcification is initiated determine ultimately the porosity of the eggshell. Such a concept implies that evolutionary pressures operate primarily upon these cells rather than on crystallisation, a process over which a bird may have no control.