Red pulp of spleen with venous sinusoids (monkey, human)

Stain: A: Silver stain (Movat) (monkey); B: Silver stain (Gomori) (human). (A): The darkly stained fibres are conspicuous in the PALS (1) area arranged in parallel rows. The blood vessels continue in the surrounding splenic sinusoids (4). The wall of the sinusoid is built as a grid, the space is surrounded with argyrophilic fibers (3) spirally wrapped around the space (4) that is lined inside with elongated endothelial cell types. The cross-sectioned reticular fibers are shown as dark dots (2). These fibres consist of collagen type III with microfibrils and enclosed by a glycoprotein coating they surround and reinforce sinusoids. Macrophages cover and embrace the reticular grid, and control the flow in the sinusoids on foreign particles. (B) The Gomori silver stain mainly shows the fine and coarse argyrophilic fibres around and between the sinusoids.