ULTRASTRUCTURE OF THE PERITONEAL-EXUDATE CELLS OF SEAWATER TELEOSTS, SEABREAM (SPARUS-AURATA) AND SEA BASS (DICENTRARCHUS-LABRAX)

The peritoneal exudates of seabream and sea bass consist of granulocyt es, lymphocytes and macrophages. These cells show conspicuous ultrastr uctural differences from the same cell-types of blood and head-kidney, which have not been reported previously. Peritoneal exudate granulocy tes differ from their corresponding circulating or head-kidney forms i n the following way: (a) they are larger in size, and (b) their abunda nt cytoplasmic granules have some new ultrastructural features, and a new granule population might also be present. Likewise, lymphocytes al so show a noticeable difference; they contain a sparse population of s mall dense cytoplasmic granules. Monocytes, macrophages, and transitio nal forms between these two cell-types, are also found. The percentage of peritoneal exudate cell-types is different in seabream and sea bas s. Macrophages in sea bass represent the most abundant peritoneal exud ate cell-type. However, seabream shows lower percentages of macrophage s than granulocytes.