Resident sinusoidal macrophages in the liver of the brown bullhead (Ictalurus nebulosus): An ultrastructural, functional and cytochemical study

Abstract

Ultrastructural, functional, and cytochemical characteristics of resident sinusoidal macrophages (RSM) in brown bullhead (Ictalurus nebulosus) liver were examined. Following perfusion fixation of the hepatic vascular bed, light micrographs revealed RSM that possessed multiple elongate cytoplasmic processes and frequently contained erythrocytes in various stages of degradation. Following brief perfusion fixation, light microscope examination of vibratome sections of bullhead liver reacted for peroxidase revealed intensely positive RSM. By transmission electron microscopy, peroxidase activity was localized to the nuclear envelope and cytoplasmic granules of RSM and in endothelial and perisinusoidal fat-storing cells. In cryostat sections of fresh-frozen liver, glucose-6-phosphate dehydrogenase (G-6-PDH) was uniformly distributed over hepatocytes, whereas intensely positive punctate staining for G-6-PDH was localized over RSM. To test for phagocytosis by RSM, latex beads (0.81 micron) were injected into a tributary of the hepatic portal vein 2 min prior to perfusion fixation. Latex beads appeared either singly or in dense aggregates within RSM. Ultrastructurally, RSM were characterized by an irregularly shaped, eccentrically located nucleus, electron-dense vacuoles, small patches of granular endoplasmic reticulum, a well-developed Golgi apparatus, elongated mitochondria, desmosomes or desmosome-like densities that served as a source of attachment to endothelial cells, and a centriole with radiating microtubules. Invaginations of the plasma membrane (vermiform processes) characteristic of mammalian Kupffer cells were not observed in bullhead RSM. The results indicated a resident cell population of sinusoidal macrophages in the bullhead liver with properties that partially resembled mammalian Kupffer cells. These results are important for the identification of the normal resident cells in the bullhead liver.

Liver of juvenile atlantic salmon, Salmo salar L.: A light, transmission, and scanning electron microscopic study, with special reference to the sinusoid

“…Histological techniques applied in this study failed to demonstrate any Kupffer cells or intraluminal pit cells (Wisse et al, 1976). The "resident sinusoidal macrophages" as demonstrated in brown bullhead catfish (Hampton et al, 1987) and channel catfish (Hinton and Pool, 1976) were not observed in Figs. 13-18.…”

Histological Methods to Determine Blood Flow Distribution with Fluorescent Microspheres

“…The organic solvents used routinely for paraffin embedding are not used for embedding in glycol methacrylate (see also Pierce and Morfitt 1989) or in epoxy resins such as Spurn's (Hampton et al 1987), Ladd Low Viscosity Epon (LeFevre et al 1985), or Epon (Herzog andMiller 1979, Rome et al 1994). Methods used routinely for processing specimens for scanning electron microscopy (fixation, dehydration in ethanol, critical point drying via CO,) also preserve microspheres that can be visualized in the scanning electron microscope (Walker et al 1994).…”

“…The appearances include clear, washed out circles (LeFevre et al 1985), pale circles (Herzog and Miller 1979), deformed circles showing dense cores (acentrically placed) with translucent rims (Hampton et al 1987), circles with pale centers surrounded by electron dense rims (Rome et al 1994), and solid electron dense circles (Villiger et al 1981). Young et al (1980) and Lung (1993) published light microscopic photomicrographs of histological sections showing densely stained microspheres.…”

Histochemistry on vibratome sections of fish tissue: a comparison of fixation and embedding methods

“…This technique is well-suited to prepare tissue sections, typically between 10 and 100 µm thick, that can subsequently be processed by histochemical, immunohistochemical or electron microscopic methods. This approach has been used for studying the brain (Kálmán & Ari 2002, Lieberoth et al 2003, Lecht reck et al 2009, Pilaz & Silver 2014, Reichmann et al 2015, cardiovascular system (Bryson et al 2011, Price et al 2014, liver (Hampton et al 1987, Satoh et al 2005) and retina and lenses (Freel et al 2003, Alvarez-Viejo et al 2004, Enski et al 2013) in fishes and other vertebrates. Whole body transverse sections are commonly used for diagnostic work to understand the full extent of the histological lesions that are caused by fish pathogens (Bruno et al 2013).…”