Structure of the glandular layer and koilin membrane in the gizzard of the adult domestic fowl (Gallus gallus domesticus)
Akester, A.R.
Journal of Anatomy 147: 1-25
1986
ISSN/ISBN: 0021-8782 PMID: 3693065 Document Number: 274601
Transmission electron microscopy of the gizzards of 4 mature domestic fowl showed that the membrane lining the gizzard (koilin, a polysaccharide-protein complex) is formed by the secretions of gland, crypt and surface epithelial cells. The glands are straight tubes, about 500 micro m long and 15 micro m in diameter, and produce rodlets of hard koilin (5 micro m in diameter) which are grouped in clusters of 5 or 6 as they pass through the crypts into the koilin membrane; they have no horizontal branches. (Rodlet clusters have previously been called 'rods'.) There is about twice as much surface koilin as rodlet koilin within the membrane. Most of the softer koilin, which fills the space between the rodlet clusters, is produced by the epithelial cells.