Cytoplasmic protrusions from an EYFP+ MK form proplatelets and intermediate swellings. Three movies of the same z-stack (21 sections, z step of 0.5 μm, pasted together. Pixel density of 512x512, over a total of 90 frames, with a frame rate of 15 s. White numbers in upper right corner are minutes and seconds, scale bar corresponds to 50μm.

Movement of proplatelets, intermediate swellings and MK progeny in the interstitium, close to the MK. Blood stream is counterstained with FITC-dextran (green). Z-stack of 12 sections (z step of 2 μm) at a pixel density of 256x256 over 200 frames, at a frame rate of 7 s. White numbers in upper left corner are minutes and seconds, scale bar corresponds to 50 &mgr;m. Second harmonic signal of the bone is visible in blue.

Elaborate proplatelets extend into the lumen of a BM sinusoid vessel. Scan of 31 sections (z step of 2 μm), at a pixel density of 512x512, averaged over three frames. White numbers in the upper right corner are depth in micrometers, scale bar correspond 50 μm.

Formation of a pseudopodium by a EYFP+ MK (red) into a BM sinusoid. The blood stream is counterstained with FITC-dextran (green), and second harmonic emission signal of the collagen appears in blue. Z-stack of 12 sections (z step of 4 &mgr;m) at a pixel density of 256x256, over 61 frames, with a frame rate of 15 s. White numbers in the upper left corner are minutes and seconds, scale bar corresponds to 50 &mgr;m. Arrowhead shows formation of MK pseudopodium at the sinusoid vessel.

Large EYFP+ fragment, potentially a whole MK (red) is shed into a BM sinusoid. It partially occludes the blood flow upstream. Blood stream is counterstained with FITCdextran (green). Six movies of the same z-stack (11 sections, z step of 4 μm) pasted together. Pixel density of 256x256, over a total of 735 frames, with a frame rate of 15 s. White numbers in upper left corner are hours, minutes and seconds, scale bar corresponds to 50 μm.

Slow shedding of EYFP+ MK fragment (red, arrowhead) into a BM sinusoid. Blood stream is counterstained with FITC-dextran (green). Z-stack of 14 sections (z step of 4 μm) at a pixel density of 256x256, over 161 frames, with a frame rate of 15 s. White numbers in upper left corner are minutes and seconds, scale bar corresponds to 50 &mgr;m. White arrowhead shows proplatelet shed into the circulation.

Rapid shedding of EYFP+ MK fragment (red, arrowhead) in a BM sinusoid by the force of the blood stream. Blood stream is counterstained with FITC-dextran (green). Z-stack of 14 sections (z step of 4 μm) at a pixel density of 256x256, over 161 frames, with a frame rate of 15 s. White numbers in upper left corner are minutes and seconds, scale bar corresponds to 50μm. White arrowhead shows proplatelet shed into the circulation.