Zebrafish thrombocyte electron micrographs.  (a) Zebrafish thrombocyte. Open canalicular like system is shown by arrowhead; N: nucleus; (b) An activated thrombocyte. Thrombocyte in an aggregation reaction; activated thrombocyte is shown by a thick arrow, thrombocyte in the aggregate shows filopodia shown by a thin arrow; E: erythrocyte [12].

Young and mature thrombocytes forming independent clusters in an aggregation reaction. Top to bottom, the panels show four different thrombocyte clusters. (a) bright field image; (b) DiI−labeled thrombocytes and mepacrine-labeled thrombocytes as green or orange; (c) DiI-labeled thrombocytes [23].

Schematic representation of sequential steps in growing arterial thrombus. Panels (a) through (e) show the sequence of events in thrombus growth. Arrowhead shows the site of laser injury in (a), (b) shows initiation of thrombus with the formation of microparticle (MP) clusters (MPC) followed by young thrombocyte (Y) clusters (YC) shown in (c) and then followed by a mixture of mature thrombocyte (M) clusters (MC) and YC as shown in (d) and (e) EC indicates endothelial cell; SE, subendothelial matrix; (e) erythrocytes; L, leukocytes. Arrows show the direction of blood flow.

Schematic representation of thrombocyte development in zebrafish larva. DA, dorsal aorta; AV, axial vein; AGM, area corresponding to mammalian aorta- gonad- mesonephros; CHT, caudal hematopoietic tissue; K, kidney; Y, yolk; YE, yolk extension; filled small circles and ovals represent GFP^Low and GFP^High thrombocytes, respectively. The yellow and blue lines with arrows correspond to the routes of immigration of the thrombocytes. Thymus is not shown. Black circle and outline show the eye and the zebrafish body, respectively.