Composition and ultrastructure of holocephalan granulocytes

Abstract

Ultrastructural observations on the lymphomyeloid tissue of 4 Rhinochimaera pacifica, 2 Harriotta raleighana, 4 Hydrolagus sp., and 4 Callorhynchus milii were correlated with blood granulocytes under the light microscope. Rhinochimaera only had fine eosinophilic granulocytes (FG) in blood and orbital tissue, but in Harriotta orbital tissue also contained coarse eosinophilic granulocytes similar to the eosinophils of higher vertebrates. Whereas FG of Harriotta contained homogeneous electron-dense granules, those of Rhinochimaera contained whorl, plate-like, and multivesiculate inclusions. Hydrolagus sp. and Callorhynchus also had a third granulocyte type that showed some similarities to the coarse granulocytes. They differed, however, in having granules containing a lucent core, apparently bounded by an ovoid vesicle-like inclusion that may pass from the granule into the cytoplasm. In Hydrolagus these granules also contained tubular structures projecting from, or connecting, granules. Granulocyte interrelationships are discussed.

Chemosensory cells in the oral epithelium of Raja clavata (Chondrichthyes)

“…Others may be macrophages. There is much uncertainty in the identification and nomenclature of selachian leucocytes (Hine & Wain, 1987). It has not been poscjible to match the leucocytes with sparse, small.…”

Observations on eosinophilic granule cells in peritoneal exudates of eels, Anguilla amtmlis

“…The EGC resemble peripheral blood eosinophils in the presence of ACP, ANBE and ASD (Hine et al, 1986a), but the reaction was generally weaker in EGC. Ultrastructurally, the large spherical to ovoid electron-dense granules are similar to those described from lampreys (Rowley & Page, 1985), some elasmobranchs (Mattisson & Fange, 1982;Honma et al, 1984) and other teleosts (Kelknyi & Nemeth, 1969;Lester & Daniels, 1975;Bielek, 1980;Cenini, 1984), and the tubular structures and lucent vesicles resemble structures observed in eosinophils of holocephalans (Hine & Wain, 1988). The dumb-bell shaped vesicular structures occur widely in mammalian eosinophils and have been regarded as specific microgranules (Schaefer et al, 1973) that may be secretory (Zucker-Franklin, 1980) and as vesicles associated with endocytosis (Komiyama & Spicer, 1975).…”

“…Fish are the largest and oldest vertebrate group, they occupy diverse habitats and show considerable variation in peripheral blood leucocyte composition (Hine c't ul., 1987). Granulocytes of the eosinophilic lineage are common in peripheral blood of chondrichthyans such as ghost sharks (Hine & Wain, 1988) and elasmobranchs (Mainwaring & Rowley, 1985) but are more variable in teleosts (Hine ct al.. 1987). The tendency of eosinophils of readily available freshwater teleosts to degranulate (Hine et al, 19866), and their scarcity (Ellis, 1977) or questionable identity (Barber & Mills Westermann, 1978), have led some workers to study eosinophilic cells at extravascular sites such as gut (Ezeasor & Stokoe, 1980;Bergeron & Woodward, 1983), skin (Blackstock & Pickering,!980), in inflammatory lesions (Lester & Daniels, 1976) and in the peritoneal cavity (Bodammer, 1986;Suzuki, 1986).…”