Studies of membrane, mammilary cores and cuticle of the hen egg shell

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Abstract
Mammillary cores and outer shell membrane have been studied by comparing the weight and chemical composition of outer membrane with cores still attached and of outer membrane free from cores, from the same shells. Inner membrane and cuticle have also been investigated. The weights of inner and outer membrane are significantly correlated (P < 0.05). Both membranes contain galactosamine, glucosamine, sialic acid, glucose, mannose and fucose but in different proportions. Uronic acid is probably absent. An average of 3.3 mg of organic mammillary core material per shell (52 μg/cm2) was present in the shells investigated, but there was a trend suggesting that eggs laid by more mature hens may contain rather more. Cores are rich in hexo‐samine, sialic acid and hexose, but the probable absence of uronic acid suggests that chondroitin sulphates play no part in shell initiation. There were no major differences in the amino acid spectrum of membrane samples with and without cores. Galactosamine, glucosamine, sialic acid, galactose, glucose, mannose, fucose and an unidentified pentose are present in the cuticle. In some respects these sugars are combined differently from their combination in the adjacent outer levels of the matrix.