La queratotaxia cercariana en la diferenciacion de sexos de schistosoma mansoni

the number and pattern of argentophilic papillae (chaetotaxy) of schistosoma mansoni cercariae, permits the differentiation between the male and the female of this larval stage, through the following criteria: - a greater homogenity in the male cercariae concerning the number of ventral and dorsal papillae on the body and tail (c.v.= 4.1%), than in the female cercariae (c.v.=18.3%) (p<0.001). - the presence in the 80% of the male cercariae of papillae on the inferior-right and left quadrant, respectively, on the ventral surface; while this criterion is only present in the 40% of the female cercariae (p<0.001). a significative statistical difference (p<0.001) between the average number of ventral body papillae in the female cercariae (x =11.9 ± 0.2) and the male cercariae (x = 11.1 ± 0.3). -a significative statistical difference (p<0.05) for the average of the major distance between the papillae ail-aiil for each cercariae in relation to the sex (men = 25.5 μm, women = 27.3 μm).