Corpuscular components of the coelomic fluid were observed
in Sipunculus nudus using cytochemical and cytoenzymatic methods.
In particular, granulocytes were studied and two different
types, based on morphology, chemical composition, and function
were distinguished. Cell aggregates, identified as stem cells of
type II granulocytes, were also evidenced. Besides, empty vesicles,
vesicle fragments, laminar structures and brown bodies were
observed. Based on the observation of their structure and ultrastructure,
brown bodies were attributed with the function of accumulating
foreign material, as well as aged components typical of
the coelomic fluid
