Ki-67 is a protein expressed in the nucleus of several species during cell-division, being absent during the GO resting phase of the cellular cycle. During attempts to disclose mitosis in the so-called "amebocyte-producing organ" in Biomphalaria glabrata
infected with Schistosoma mansoni
, the parasite multiplying forms appeared strongly marked for Ki-67, while the snail tissues were completely negative. These data are worth registering to complement general data on Ki-67, and to help future studies on the relationship of the parasite and of its intermediate host.