review of the cellular response to injury in marine shrimp of
the genus Penaeus is presented. Studies on the inflammatory response of
penaeid shrimp have shown six cell forms that respond to injury. These include
three forms of hemocytes, fibrocytes, phagocytic cells of the loose connective
tissue, and fixed phagocytes lining blood sinuses.
The cellular defense mechanism is dependent upon the activity of the hemocytes.
One type of hemocyte apparently engages in encapsulating foreign
material while the other two types phagocytize and eliminate foreign or
necrotic material by migrating to the external surface. Later, additional
phagocytosis is accomplished by "fixed" phagocytes in the loose connective
tissue and by cells that line hemolymph sinuses of the heart, gill, and abdomen.
Collagen-like fibers are typically seen in association with wound healing and
in the process of encapsulation in these animals. The dense network of
collagen-like fibers and fibrocytes develops in close association with earlier
hemocytic encapsulation or deposits. This fibrous tissue is stable, not resorbed,
and remains as a permanent "scar.