Cell type specific CD antibodies. The specificity of antibodies directed at luminal secretory (CD26), endothelial (CD31), stromal fibromuscular (CD49a), and basal epithelial (CD104) cells are demonstrated. Brown color indicates positive staining. Each prostatic gland is composed of a one-cell layer thick basal epithelium surmounted by columnar secretory cells enclosing the luminal space. The interglandular stroma contains the fibromuscular cells and various other cell types.