Ultrastructure of the Resin Ducts of Mangifera indica L. (Anacardiaceae). 3. Secretion of the Protein-polysaccharide Mucilage in the Fruit

Abstract

Mango fruit ducts secrete a protein-carbohydrate mucilage in addition to lipophilic material. This mucilage is secreted in special duct regions. Loops of ER elements seem to delimit cytoplasmic portions rich in ribosomes forming pseudo-vacuoles which eventually become bound by a single membrane of ER origin. It is suggested that the protein is produced and accumulates in the pseudo-vacuoles which become storage bodies. Carbohydrates are added to the content of these bodies by Golgi vesicles. The cytoplasm becomes osmiophilic and contracts before disintegration, and the mucilage passes into the space between plasmalemma and cell wall. After the cell breaks down the mucilage is released into the duct cavity.