Normal LN development in Clec1b^fl/flPF4-Cre newborns. (A) Macroscopic observation of newborns Clec1b^fl/flPF4-Cre and Clec1b^fl/fl littermates revealed the presence of inguinal and mesenteric LNs in Clec1b^fl/flPF4-Cre newborns. Fraction of number of newborn mice with detectable LN/number of mice sacrificed. (B) Flow cytometric analysis of mesenteric LN single-cell suspensions from Clec1b^fl/flPF4-Cre and Clec1b^fl/fl newborn littermates stained with CD45, CD4, ICAM-1, and VCAM-1. Percentage of CD45⁺ hematopoietic cells is shown in the histogram; percentages of CD45⁺CD4⁺ LTi cells (second column) and of ICAM-1^highVAM-1^high LTo cells in the CD45⁻ stromal fraction (third column) are shown in the dot plots. (C) Immunofluorescence staining of sections from newborn mesenteric LNs showing the CD31⁺ blood endothelial vasculature in red and the Lyve-1⁺ LECs in green forming the subcapsular sinus (first column) and the Gp38⁺ stromal cell compartment in red and CD4⁺ cells in blue (second column) in Clec1b^fl/fl (upper row) and Clec1b^fl/flPF4-Cre littermates (lower row).