Developmental kinetics of KL cells in murine AF and Am and in human AF. (A) Murine AF and Am were collected from E9.5 up to E19.5 and analyzed by flow cytometry. Mononuclear cells from AF, Am, FL, and EB were stained with Viaprobe (7-AAD) and a combination of antilineage (Lin) markers and anti–c-Kit antibodies. Lin and c-Kit expression is shown for viable (7-AAD⁻) GFP⁺ cells, to exclude any maternal (GFP⁻) contamination. Numbers represent percentages of cells. We used an inverted Leica DM1RB microscope (10× magnification). Pictures of colonies were taken with a Leica DC350F camera and processed with LeicaQFluoro software (Leica Microsystems). (B) The percentage of AFKL cells as a function of the gestation stage is indicated in the left panel. The middle panel shows the total number of mAFKL cells per embryo equivalent (EE). The right panel indicates the percentage of mAmKL cells among total live cells. Means are represented by bars. (C) Human AF was collected from 7 weeks of amenorrhea up to 35 weeks of amenorrhea. 7-AAD⁻ mononuclear cells were stained with a combination of antilineage (Lin) markers and anti–c-Kit antibodies. Isotype controls are shown in the left panel. (D) The percentage of hAFKL cells relative to total live cells is shown as a mean and SD as a function of the gestation stage. The total number of hAFKL cells estimated for each period (mean AF volume multiplied by mean cellularity of the samples) is indicated below the graph.