Fibroblasts are the principal cells of connective tissue. Distributed widely throughout the body, connective tissue exhibits a relatively few number of cells and a relatively large amount of intercellular substance. The cells of the tissue consist of macrophages, adipose cells, mast cells, lymphocytes, monocytes, eosinophils, and plasma cells, in addition to fibroblasts. The matrix secreted by the cells is comprised of the amorphous, hydrated material known as ground substance and fibers. Among the chief functions of connective tissue are imparting structural support and assisting in the protection of the body, as well as providing a site for fat storage.

In the digital image above, a Swiss mouse embryo fibroblast cell is presented that was resident in a culture labeled with the fluorophore Texas Red-X conjugated to wheat germ agglutinin, a fluorescent lectin that selectively binds to sialic acid residues. Wheat germ agglutinin conjugates are often used as probes for the Golgi network in mammalian cultures. The cells were also stained with Alexa Fluor 488 conjugated to phalloidin and DAPI, which target F-actin and DNA, respectively. Images were recorded in grayscale with a QImaging Retiga Fast-EXi camera system coupled to an Olympus BX-51 microscope equipped with bandpass emission fluorescence filter optical blocks provided by Omega Optical. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.