In order to clarify the mechanism of osmoregulation of the larval red seabream
Pagrus major (Temminck et Schlegel), chloride cells of the larvae were observed from immediately after hatching to 15 days using the silver staining technique.Numerous silver-stained cells, round or elliptical in shape and 7.5-14.9 μ in diameter, were noticed as black small bodies on the whole integument of larvae.The cross section indicated that these cells were found within the epithelium.The central part of silver-stained cells was more blackly stained, where a lip or rent-like structure was found as an orifice.The network binding the silver-stained cells was also observed on the body surface.
The fluctuation of the number of silver-stained cells with different developmental stages was summarized as follows: The cells were already found on the all body surface in larvae im-mediately after hatching.Silver-stained cells increased in number up to 5 days, then decreased after about 8 days, and disappeared around 15 days after hatching.
Silver-stained cells are likely to be chloride cells, according to previous findings.If this assumption is true, seabream larvae are provided with chloride cells in the epithelium of the skin to regulate osmotic pressure.
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