Increased localization of eMks within aneurysm-like sprouts and PNVP of Pdpn^−/− and Clec-2^−/− lower diencephalon. (A) Confocal images of aneurysmlike sprouts with eMks (asterisks) and platelets. CD41 marks eMks and platelets. (B) Confocal images and representative quantified number of eMks and platelets (Plts) in the diencephalon. Yellow boxes indicate the lower diencephalon. CD41 marks eMks and platelets. (C) Micrograph of eMks (asterisks) double labeled with CD41 and nuclear enhanced green fluorescent protein (EGFP) within diencephalon of ntdTomato-R26;Pf4Cre embryonic brain. The tdTomato labeling of other nuclei is pseudocolored blue. (D) Flow cytometric data of E11.5 peripheral blood (PB) stained with anti-CD41 to gate eMks and with Hoechst 33342 for nuclear ploidy. Results represent 6 experiments. (E) Results of flow cytometric analysis of platelets from WT midgestation blood vs adult mouse blood. Receptor levels are represented as relative fluorescence. Data represent the mean ± standard error of the mean; n, number of replicate animals. (F) Confocal image of an eMk with proplatelet formations (arrows) within lower diencephalon vasculature. (G) Diagram showing temporal representation of primitive and definitive hematopoietic waves during embryonic development. Origin of progenitor cells (blue arrows) and location of hematopoiesis (green arrows) are indicated. AGM, aorta-gonad-mesonephros. (H) Graph represents the ratio of eMks to platelets within embryonic PB. Scale bars, 20 μm (A-C); 100 μm (B); and 10 μm (F). **P < .01.