Galactogen is synthesized by secretory cells in the albumen gland of adult female snails and later transferred to the egg. This process is under neurohormonal control, notably by the brain galactogenin. The biochemical pathways for glycogen and galactogen synthesis are closely related. Both use glucose as a common precursor and its conversion to activated galactose is catalyzed by UDP-glucose 4-epimerase and galactose-1-P uridyl-transferase. This enables glucose to be the common precursor for both glycogenesis and galactogenesis.  In fact, both polysaccharides are found in the same secretory cells of the albumen gland and are subject to independent seasonal variations. Glycogen accumulates in autumn as a general energy storage for hibernation, whereas galactogen is synthesized during spring in preparation of egg-laying. It is commonly accepted that galactogen production is restricted to embryo nutrition and therefore is mainly transferred to eggs.
Little is known about the galactogen-synthesizing enzymes. A D-galactosyltransferase was described in the albumen gland of Helix pomatia. This enzyme catalyzes the transfer of D-galactose to a (1→6) linkage and is dependent upon the presence of acceptor galactogen. Similarly, a β-(1→3)-galactosyltransferase activity has been detected in albumen gland extracts from Limnaea stagnalis.
In embryos and fasting newly hatched snails, galactogen is most likely an important donor (via galactose) of metabolic intermediates. In feeding snails, the primary diet is glucose-containing starch and cellulose. These polymers are digested and contribute glucose to the pathways of intermediary metabolism. Galactogen consumption begins at the gastrula stage and continues throughout development. Up to 46-78 % of egg galactogen disappears during embryo development. The remainder is used up within the first days after hatching.
Only snail embryos and hatchlings are able to degrade galactogen, whereas other animals and even adult snails do not. β-galactosidase may be important in the release of galactose from galactogen; however, most of the catabolic pathway of this polysaccharide is still unknown.