THE ULTRASTRUCTURE OF THE SHELL FORMING REGION OF THE OVIDUCT AND THE DEVELOPMENT OF THE SHELL OF GALLUS DOMESTICUS

Abstract

In the hen's oviduct, the granular epithelial cells of the red region and shell gland secrete the protein carbohydrate substance of the mammillae and organic shell matrix, and the glycogen contributes the increased glucose content first noted when the egg is in the red region. The gland cells transport the 15 g of water required for ‘plumping’ the egg, and the calcium for the crystal formation which commences in the mammillae. The mammillae first appear in the red region and remain discrete until the shell matrix is added in the shell gland. The fibres of the external fibre membrane form a lattice within the substance of a mammilla. These are the nucleation sites of calcite crystals. The so called ‘mammillary’ cores are not in the substance of the mammillae but are intimately related to a fibre of the external shell membrane, and the ordered arrangement of their substance is in continuity with the fibre lattice pattern. No developing shell was obtained with an uncalcified organic matrix.