Localization patterns and morphology of CD68-positive cells of the monocyte/macrophage lineage at tumor site and the CD68 expression by tumor cells. Immunohistochemical staining of tissue sections that were obtained from patients with serous ovarian cancer. CD68 belongs to the lysosomal/endosomal-associated membrane glycoprotein (LAMP) family and primarily localizes to lysosomes and endosomes with a smaller fraction circulating to the cell surface. Representative images of various sub-populations of CD68-positive leukocytes are shown: (a) elongated well-spread intra-tumoral macrophages, (b) macrophage accumulation at the tumor – stroma border, (c) accumulation of round shaped monocytes in mucous tissue, (d,e) large phagocytes organized into phagocytic islands, (f) accumulation of macrophages in adipose tissue. Expression of CD68 by tumor cells: representative images of ovarian cancer specimens (n = 6) showing (g-i) the absence or (j-l) presence of CD68 expression by tumor cells. Brown color, CD68 staining; blue color, nuclear counterstaining with hematoxylin. Scale bar: 50 μm. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)