[Investigations on the filariidae of the cervidae in Southern Germany. 1. Development of the nodule, finding of the sexes and production of the microfilariae in Onchocerca flexuosa (Wedl, 1856), in the red deer (Cervus elaphus) (author's transl)].

The biology of O. flexuosa was studied during the examination of numerous subcutaneous nodules, which were taken from the hides of red deer of all age-classes. In fawns the development of the nodule is induced by the immature stages, probably by the females. At the same time a hematome is formed. Males of different ages penetrate into the nodule where mature or immature females are present. Later they mate and remain within the nodule until the microfilariae in the uteri of the females develop. Usually 1 or 2, occasionally 4 females are found together. During the development of the embryos in the uteri the initially stretched female winds up. Only a short anterior part remains always straight. It is put out through the wall of the capsule in order to release the microfilariae. The males are often the majority reaching to 13 in one nodule. During the release of the microfilariae the males are found outside the nodule on the surface or near-by in the subcutaneous connective tissue. Both sexes are able to mate a second time. In older deer the males are also able to induce the development of nodules.