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

¹ Department of Anatomy, University of Glasgow, Glasgow G12 8QQ and the Agricultural Research Council's Poultry Research Centre, King's Buildings, West Mains Road, Edinburgh EH9 3JS

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.

Note:

We wish to thank Mr R. N. Foxton of the Poultry Research Centre, Edinburgh, for contributing the quantitative data on glycogen content of the ‘red region’ of the oviduct, and the mineral analysis.

We are grateful to Miss Margaret Hughes of the photographic unit and Mr Peter Smellie of the electron microscopy unit, Anatomy Department, Glasgow University, for their technical assistance.