A type II keratin is expressed in glial cells of the goldfish visual pathway

Keratin 8 and 18 expression in mesenchymal progenitor cells of regenerating limbs is associated with cell proliferation and differentiation

“…This apparent expression of K8 and K18 in mesenchymal cells is puzzling because cytokeratins, obligatory heteropolymers encoded by two large multigene families, are usually considered markers of epithelial differentiation and are normally expressed in glandular epithelia. In lower vertebrates, keratin immunoreactivity has also been reported in some nonepithelial tissues that grow throughout life and have significant regenerative ability, such as optic nerve and fins in fish (Giordano et al, 1989;Ferretti et al, in preparation), and in regeneration blastemas of different organs in amphibians (Ferretti et al, 1989;Ferretti and Ghosh, 1997). Furthermore, K8 and K18 are present in the oocyte and are among the first genes to be activated during embryogenesis when the cells are still pluripotent and no differentiation is apparent.…”

Homeobox genes are expressed in the retina and brain of adult goldfish.

“…These developmental and regenerative properties are not observed in the adult visual pathways of higher vertebrates. Thus, the goldfish visual pathway has emerged as an important model system to study molecular events associated with axonal growth and neurogenesis (9)(10)(11)(12).…”

Fibroblasts at the transection site of the injured goldfish optic nerve and their potential role during retinal axonal regeneration

“…Consistent with previous findings on crushed optic nerves (Levine, 1991), astrocytes remain absent from the lesion site in our preparations for roughly 10 days, whereas they represent normal and persisting components of the proximal and distal nerve stumps (Maggs and Scholes, 1986). Fish astrocytes can be identified by antibodies against specific forms of cytokeratins (Giordano et al, 1989(Giordano et al, , 1990Levine, 1991) and vimentin (Maggs and Scholes, 1986), and by anti-GFAP, particularly after lesioning the optic nerve (Stafford et al, 1990;Levine, 1991). At the ultrastructural level, astrocytes are recognized in particular by their content of intermediate filaments and their striking desmosomes (Maggs and Scholes, 1990;Strobel and Stuermer, 1994).…”

“…Ib), which often appeared brighter on what may represent the basal lamina than in the interfas cicular spaces proper. Anti-cytokeratin antibodies (Markl and Franke, 1988;Giordano et al , 1989Giordano et al , , 1990) and anti vimentin (Maggs and Scholes, 1986), both markers for astrocytes in normal fish optic nerves, delineated the fascicle borders and the astrocytic partitions (Maggs and Scholes, 1990) therein ( When the interfascicular area and outer nerve sheath were examined electron microscopically, one of the most conspicuous elements present were fibroblasts. In the interfascicular spaces, long fibroblast processes and bundles of collagen fibrils ran parallel to the glia limitans covering the fascicles (Fig.…”