Vitamin A (retinol and retinyl ester) distribution and content in tissues of a lamprey (Lampetra japonica) were analyzed by morphological methods, namely, gold chloride staining, fluorescence microscopy to detect specific vitamin A autofluorescence, and electron microscopy, as well as high-performance liquid chromatography (HPLC). Hepatic stellate cells showed an abundance of vitamin A stored in lipid droplets in their cytoplasm. Similar cells storing vitamin A were present in the intestine, kidney, gill, and heart in both female and male lampreys. Morphological data obtained by gold chloride staining method, fluorescence microscopy, transmission electron microscopy, and HPLC quantification of retinol were consistent. The highest level of total retinol measured by HPLC was found in the intestine. The second and third highest concentrations of vitamin A were found in the liver and the kidney, respectively. These vitamin A-storing cells were not epithelial cells, but mesoderm-derived cells. We propose as a hypothesis that these cells belong to the stellate cell system (family) that stores vitamin A and regulates homeostasis of the vitamin in the whole body in the lamprey. Fibroblastic cells in the skin and somatic muscle stored little vitamin A. These results indicate that there is difference in the vitamin A-storing capacity between the splanchnic and intermediate mesoderm-derived cells (stellate cells) and somatic and dorsal mesoderm-derived cells (fibroblasts) in the lamprey. Stellate cells derived from the splanchnic and intermediate mesoderm have high capacity and fibroblasts derived from the somatic and dorsal mesoderm have low capacity for the storage of vitamin A in the lamprey.
Copyright 2004 Wiley-Liss, Inc.