Unusually complex basement membranes in the midgut of two decapod crustaceans, the stone crab (Menippe mercenaria) and the lobster (Homarus americanus)

Ultrastructural studies of the stone crab (Menippe mercenaria) and the lobster (Homarus americanus) demonstrate that the basement membrane of the midgut (intestine) is unusually complex. In both species, the basement membrane is three‐layered and has processes that form extensive networks protruding into the connective tissue. The possible functional significance of this complex structure is discussed.