Neutrophils interact with the MK endoplasmic reticulum as well as the DMS. MKs were allowed to engage in EP for 12 hours followed by processing for EM or laser scanning confocal microscopy. (A) Transmission EM images of EP. The internalized neutrophil is surrounded by a membrane network (arrowheads) that does not resemble the DMS. Scale bars, 2 µm. (B-D) Cells were stained with anti-CD41 APC (white), anti-Ly6G AF594 (red), anti-calnexin or anti-golgin-97 (green), and Hoechst 33342 (blue). Images were obtained using a Zeiss LSM 800 with Airyscan attached to a Zeiss Axio Observer Z1 Inverted Microscope with a Plan-Apochromat 63x objective. Scale bars, 10 µm. (B-C) The perinuclear portion of the MK endoplasmic reticulum (ER) surrounds the internalized neutrophils (*s). The neutrophils are localized between the MK nucleus and ER. Note the inverse distribution of the DMS and ER. (D) Internalized neutrophils (*) did not colocalize with the Golgi apparatus of MKs.