Identity of the cells recruited to a lesion in the central nervous system of a decapod crustacean

In a previous study, we analyzed and described the features of the degeneration of the protocerebral tract (PCT) of the crustacean Ucides cordatus, after the extirpation of the eyestalk. In that study, among axons with axoplasmic degeneration, cells with granules resembling blood cells (hemocytes) were seen. Therefore, in the present study, we characterized the circulating hemocytes and compared them with the cells recruited to a lesion, which was produced as in the former study. Using histochemistry, immunohistochemistry, and electron microscopy (transmission and scanning), we confirmed that circulating and recruited cells display a similar morphology. Therefore, in the crab, hemocytes were attracted to the lesion site in the acute stage of degeneration, appearing near local glial cells that showed signs of being responsive. Some of the attracted hemocytes displayed a morphology that was considered to be possibly activated blood cells. Also, the cells that migrated to the injured PCT displayed features, such as the presence of hydrolytic enzymes and an ability to phagocytize neural debris, similar to those of vertebrates. In summary, our results indicate that hemocytes were not only phagocytizing neural debris together with glial cells but also that they may be concerned with creating a favorable environment for regenerating events.