Immunogold labelling reveals intense distribution of hyaluronate in the regenerating fin blastema of the goldfish

Abstract

AbstractImmunogold labelling reveals intense distribution of hyaluronate in the regenerating fin blastema of the goldfish (Acta Zoologica, Stockolm). Caudal fin regeneration in goldfish has been analysed at 3–16 days after tail amputation by light and electron microscopy immunocytochemistry. Hyaluronate is detected using a biotinilated hyaluronate binding protein and anti‐biotin antibodies coupled to gold and silver intensification. Hyaluronate appears among migrating keratinocytes of the wound epidermis and mesenchymal cells of the blastema at 3–6 days post‐amputation. Immunofluorescence for 5BrdU indicates that most proliferation of the wound epidermis and blastema occurs among mesenchymal and bone cells of the amputated lepidotrichia. Few keratinocytes proliferate indicating they mainly derive by migration from the stump borders. Among blastema and epithelial cells, numerous apparently pycnotic cells are present at 3–6 days of regeneration, most identified as immune cells. Silver intensification clearly shows that blastema cells are surrounded by hyaluronate suggesting that this glycosaminoglycan limits the contact between immune and blastema cells, perhaps avoiding an immune reaction that would damage survival of the blastema. Hyaluronate labelling decreases between connective and bone cells in proximal regions at 14–16 days post‐amputation and is low to absent in normal stump tissues. The study suggests that a high level of hyaluronate located among cells is essential for the formation of a regenerating blastema in fish and in other vertebrates.