The paired hepatopancreatic ducts of the Gammarus
pulex arise ventrally near the junction of the stomodaeal
foregut and the endodermal midgut. Each duct divides
into two hepatopancreatic caeca at the level of the
second pereionic segment, and the two pairs of tapered,
blind caeca extend ventrolaterally to the midgut well
into the pleon (Fig. 2) (Schultz, 1974). The monolayer of
glandular, columnar epithelium lining the caeca bears an
apical brush border throughout and rests on an
amorphous basement membrane (Schultz, 1974).
Each caecum consists of three regions which form a
continuum