Data for measure atherosclerotic plaque in mice treated with homocysteina. This dataset contains data for measuring atherosclerotic plaque in mice treated with homocysteine. The dataset includes one GraphPad file with the statistical analysis, and one file titled Variables to explain the information of the other csv files. Additionally, there are two folders corresponding to two separate experiments (TANDA 8 and TANDA 9). Each folder contains csv files (ORO_Staining_Tanda 8 or 9) documenting the measurements of plaque size and lipid content in the aortic roots of female mice treated with homocysteine (1.8g/L DL-Hcy, H4628, Sigma-Aldrich) or regular water. Inside, individual folders numbered by sample contain .tif images of the aortic roots for each mouse. The images include 4–5 slides (captured at the beginning, middle, and end of the aortic root to ensure accurate plaque quantification) with three sections each (6μm thick, labeled A, B, or C). Additionally, there is a folder containing the RoiSet_ORO files for each plaque. Also, it includes a README file. This dataset allows for the comparison of plaque size and lipid content between female mice treated with homocysteine and control mice (given regular water). Methodological information: 8 weeks female ApoE KO mice (on a C57BL/6J background were obtained from the Jackson Laboratory (Bar Harbor, Maine, USA). To induce moderate HHcy, 8-week-old ApoE-/- mice on a standard chow diet were treated with 1.8 g/L DL-Hcy. At 20 weeks old, and the entire aortas, hearts, and livers, were taken for further analysis. Murine hearts were perfused with phosphate-buffered saline (PBS), extracted from mice, fixed in 4% paraformaldehyde (PFA) for 4 hours at 4ºC, washed with PBS for 1 hour, and incubated overnight in 30% sucrose. Subsequently, the tissues were embedded in OCT and immediately frozen. Murine hearts were cut transversely in 6 μm serial sections starting in the ascending aorta of the aortic root up to the aortic sinus with a cryostat Leica CM1950 (Leica Biosystems, Wetzlar, Germany), and were collected in a series over 20 slides with 3 sections per slide. To ensure consistency between animals, sections were assessed from the first appearance of the aortic cusps, and subsequent slides were assigned to a staining method across all animals. To quantify the aortic lesion size, sections were stained with Oil Red O (Sigma-Aldrich, Saint Louis, Missouri, USA). In each mouse, aortic lesion size was obtained by delineating boundary lines around the plaques and averaging the area in at least five sections from the same animal. Oil Red O staining was also used for neutral lipid content assessment.