ST3Gal-IV promotes development of early thymic progenitors but is dispensable for the CLP and LSK populations. Flow cytometric analysis of MBMC mice generated as described in Figure 1. (A) Contour plots from bone marrow samples show the frequency of WT donor cells (CD45.1⁺CD45.2⁺), ST3Gal-IV–deficient (KO) donor cells (CD45.1⁻CD45.2⁺), and WT recipient cells (CD45.1⁺CD45.2⁻) from CLP (Lin⁻CD127⁺c-Kit⁺Sca-1⁺) and LSK (Lin⁻CD127⁻c-Kit⁺Sca-1⁺) populations of 1 representative mouse. (B) Contour plots show the frequency of WT donor cells (CD45.1⁺CD45.2⁺), ST3Gal-IV–deficient (KO) donor cells (CD45.1⁻CD45.2⁺), and WT recipient cells (CD45.1⁺CD45.2⁻) from the ETP population (Lin⁻CD25⁻CD44⁺c-Kit⁺) in the thymus of 1 representative mouse. Bar graphs in panels A and B show the mean ± SEM frequency of WT (blue) and ST3Gal-IV–deficient (red) cells among total donor cells from 2 independent experiments with 14 total mice per group. ***P < .001 by 2-tailed Student t test. n.s., not significant.