The dissolution of microfilariae of Onchocerca volvulus in the human eye and its effect on the tissues

Abstract

1. 1) Structural alterations in the parasite body of four types, in sections of the human eye stained with haematoxylin and eosin, and phloxine tartrazine, are described. It is believed they represent four stages in the dissolution of the mf. body. 2. 2) The local reaction of the tissues in relation to each of the four stages is reported. 3. 3) The living parasite appears to induce no tissue reaction. After its death, however, eosinophil leucocytes, lymphocytes, plasma cells and fibroblasts appear in the vicinity of the disintegrating body, roughly in that order and relative proportion; new capillaries grow towards the focus. When dissolution is complete the proportionate representation of these cells is reversed. (At no stage in the process are polyblasts or giant cells seen). 4. 4) It seems probable that, after the visible processes of dissolution are complete, ultra-microscopic toxins in solution are left to diffuse slowly into and affect neighbouring tissues and structures. This can be recognized by a diffuse basophil staining of the tissues in which the characteristic inflammatory cells lie.