The main goal of this work is to bring together Fuzzy Logic techniques and Biomedical images analysis, linking this two fields through an image segmentation problem approached by a Fuzzy c-Means algorithm. This work has two main cores. The first one is a formal structural analysis of some Fuzzy Logic concepts within the theory of Indistinguishabilitty Operators. The main actors of this part will be indistinguishability operators, sets of extensional fuzzy subsets, upper approximation operators and lower approximation operators. All these concepts will be explained in depth further in this work. The second core is a practical application of the Fuzzy c-Means algorithm to segmentate biomedical images of mammographies and bone marrow microscopical captures.