RESUMEN
After i.v. injection of 833 x 10(3) microfilariae (mf) per animal (150 g) into naive recipient cotton rats, at autopsy 15 min thereafter 30.4% of them could be recovered as a total: 19.1% were proved in the peripheral circulating blood (PCB) completely intact. 6.5% were recovered by perfusion of the lungs, of which 3/5 were associated with adherent macrophages and neutrophils or partly disintegrated. By perfusion of the liver only 3.8% were obtained, in spite of the four times greater volume of blood, of which 2/3 had adherent cells or were partly disintegrated. 0.7% and 0.3% were recovered from kidneys and spleen, respectively. In patent animals with adult worms the permanently delivered mf were distributed as follows: 41.6% were proved in the PCB; by perfusion 19.1% were obtained from the lungs and 32.9% from the liver; the rest of 6.4% were found in kidneys and spleen. In the capillary systems of lungs as well as the liver the proportion of normal mf (1/3), with adherent cells (1/3), partly disintegrated ones (1/5) and fragments (1/20) were quite similar. In long term mf injection experiments using the same dosage the autopsy was done 30 min and 1, 2, 3 and 28 days p. inj. of mf into naive animals. 30 min p.inj. 56% of the mf injected could be recovered as a total: 28.6% were obtained from the PCB, 16.0% from the lungs and 7.1% from the liver as normal mf (no perfusion), the rest of 4.1% from heart muscle, kidneys and spleen.(ABSTRACT TRUNCATED AT 250 WORDS)