Events associated with premolt reformation of the cuticularized ductule in the underdeveloped (immature) branchial rosette glands, which are common in the gills of small (14-18 mmn, total length) grass shrimp, are described and contrasted with the events of ductule reformation in the fully developed (mature) rosette glands most common in larger shrimp. Cytoplasmic processes comparable to those in mature glands, but relatively few in number and originating only from the secretory cells, are seen together with ciliary processes in some immature glands. The relative abundance of cytoplasmic processes in the mature glands, coupled with the observation that transitory ciliary processes occur in immature glands but not in mature glands, suggests that during glandular maturation transitory ciliary processes are replaced by transitory cytoplasmic processes.