Some Phases of Wound Healing in an Insect (Melanoplus differentialis)

A stuck was made of the inflammatory processes and stages of repair following the production of wounds by incision and excision in the fifth abdominal sternite of both nymphs and adults. The following changes may be observed to take place: A clot is formed in the wound aperture, consisting of agglutinated blood cells. Blood serum filters through this structure and hardens by evaporation of water on contact with air, thus sealing the wound. A brown deposit is formed in the clot and in the surrounding zone of injury. Pycnosis takes place in adjacent tissues. A further agglutination of blood cells follows. The hypodermis cells of the adult enlarge and assume a condition comparable to that found normally in the nymph. These cells begin secretion of materials similar to those found in the endocuticula. The blood cells undergo differentiation and elaborate a type of scar tissue in and about the wound area. The cells of the hypodermis proliferate and migrate in between the body wall and the newly fanned connective tissue, thus restoring continuity between the broken layers of epithelium. New endocuticula is then elaborated by these cells at the point where the body wall has been broken. Mechanical injury to the tissues of the body wall of the grasshopper will activate other tissues for some distance from the wound and cause agglutination of blood cells which differentiate and produce scar tissue. The rate of repair, within certain limits, is greater in large wounds than in small wounds