1.1 Normal appendix wall. Mucosa (white arrow) : glandular covering epithelium (arrowheads) and crypts ( angular arrows ). Submucosa (red arrow) : connective and lymphoid tissue , the latter forming follicles ( curved arrows). Muscular layer (green arrow) . Subserosa (yellow arrow). In haematoxylin – eosin stain, haematoxylin is basophilic and stains cell nuclei whereas eosin is acidophilic and stains cell cytoplasm. Mature small lymphocytes have very little cytoplasm and thus are basophilic – purple; on the contrary, muscle cells (green arrow) have abundant cytoplasm so as to contract and thus are acidophilic – pink.
1.2 Acute ulcerative inflammation. Replacement of appendix mucosa by inflammatory granulation tissue with neovascularization ( red arrows ) . Remnants of superficial covering glandular-cylindrical epithelium (white arrows).
1.3 Inflammatory granulation tissue. Purulent inflammatory exhudate (white arrow) , newly formed thin walled blood vessels (red arrows) , basophilia of inflammatory cells.
1.4 Subserosal inflammatory exhudates. Mature adipose tissue (white arrows) in subserosa of the appendix. Inflammatory cells aggregates (purple arrows) . Danger of inflammation invasion of adjacent peritoneal cavity (acute peritonitis).
1.5 Predominance of neutrophils (purple arrows) in the inflammatory exhudate (acute inflammation of bacterial pathogenesis). Entrance in venules (arrowheads) of the subserosa. Danger of haematogenous spread through the portal circulation to the liver and microabsceses formation.