Cytological observations on the blood and hemopoietic tissue in the crab, Callinectes sapidus. I. The fine structure of hemocytes from intermolt animals

A fine structural analysis of hemocytes recovered from the pericardial sinus of the blue crab (Callinectes sapidus) demonstrates that hyaline cells, intermediate cells, and granulocytes are present in the hemolymph. A detailed consideration of their shared and differing cytological features suggests that the various blood cells represent different stages of cytogenesis along a common or single path of cellular differentiation. The potential functional complexity of the hemocytes is attested to by the occurrence within their cytoplasm of three and/or possibly four morphologically distinct types of inclusion bodies, and other membrane-bounded compartments (e.g., lysosome-like structures, autophagic vacuoles, peroxisome-like bodies) whose function is unknown. Preliminary examination of the well-developed Golgi organelle in the intermediate cells and granulocytes indicates its probable participation in the elaboration of the inclusion bodies; however, the details of its role in granulogenesis and in the known plurifunctional capacities of these cells remain obscure.

The role of the haemocytes of Clitumnus extradentatus in haemolymph coagulation

Light and electron-microscopic observations of the blood cells (haemocytes) of the stick insect Clitummus extradentatus in vitro showed that two morphologically distinct cell types, the cystocytes and granular cells are involved in haemolymph coagulation. Both these cell types contain a variable number of electron-dense granules which upon release cause progressive coagulation and precipitation of the haemolymph. In the cystocytes this release is extremely rapid (30-60s) while in the granular cells it only occurs after 1-2 min in vitro. The role of these cells in haemostasis is discussed together with the possible significance of the involvement of two cell types in the coagulation process.

Studies on the in vivo cellular reactions of insects: an ultrastructural analysis of nodule formation in Galleria mellonella

Cellular aggregates or nodules which formed in Galleria mellonella larvae in response to injections of killed Bacillus cereus were examined during their first 24 hr of development. The initial aggregation stage was very rapid, occurring within 1 min, and was brought about by the release of an adhesive flocculent material by granular haemocytes in contact with the bacteria. This material, which subsequently became increasingly electron dense owing to melanin deposition, consolidated and by 5 min ramified all the intercellular spaces. The granular cells degenerated, releasing portions of cytoplasm form their peripheries, and eventurally appeared in the matrix as voids containing loosely flocculent material. No bacterial breakdown was seen, however. From 2-4 hr, plasmatocytes began to encapsulate the necrotic mass, and by 24 hr a complete sheath, composed of three discrete regions of cells, was formed. These findings are discussed in relation to the various proposed mechanisms of nodule and capsule formation.

[Ultrastructural aspects of Carcinus maenas L. hemocytes (Crustacea, Decapoda), parasitized by Sacculina carcini Thompson (Crustacea, Cirripeda) : reactive activity, collagen genesis]

The collagen embedding Sacculina roots is synthesized by hemocytes of Carcinus maenas and is described. Hemocytes engaged in the secretion of collagen as a reaction against a parasite constitute a defensive mechanism still largely unknown within Crustacea.

The granular cells of Galleria mellonella during clotting and phagocytic reactions in vitro

Light and electron-microscopic observations of the blood-cells (hemocytes) of the wax-moth Galleria mellonella showed that hemolymph coagulation was initiated by the rapid release of material from the granular cells. During incubation for short terms in vitro these cells showed progressive degranulation as material derived from the granules was discharged into the hemolymph. Attempts to determine the nature of this material by staining with ruthenium red proved mainly unsuccessful. When challenged with bacteria in vitro the granular cells failed to phagocytose these particles and instead the bacteria became embedded in the granular material surrounding these cells. The mode of coagulation reported here is compared with previous reports of the role of invertebrate hemocytes in hemolymph clotting.