Minoxidil and PGE ₂ have beneficial growth effects in vivo on developing thymuses. (A–D) Timed pregnant mice were obtained from Tbx1^+/neo2 intercrosses and injected with carrier, minoxidil, or PGE₂ at E8, E9, and E10. Fetal thymic lobes were isolated from embryos at E13–13.5 and processed for flow cytometry to determine the percentage of mesenchymal cells (Pdgfra⁺) and TECs (EpCAM⁺). (A) Minoxidil had no statistically significant difference on mesenchymal or TEC cell percentages. (B and C) Flow cytometric analyses were used to compare the mesenchymal (Mes) and TEC subset percentages after PGE₂ treatments. The absolute cell numbers are presented. (D) The percent of ETPs was compared among embryos from all the carrier or drug treatment groups. (E and F) Timed pregnant mice were obtained from Tbx1^+/neo2 intercrosses and injected with carrier, minoxidil, or PGE₂ at E8, E9, and E10. Fetal thymic lobes were isolated from embryos at E17–17.5. Single-cell suspensions were prepared. The percent of DP and SP thymocytes was determined following CD4 and CD8 co-receptor staining, followed by flow analysis to detect co-expression of CD4 and CD8 or unique expression of just CD4 or CD8, representing SP cells. These were presented in the minoxidil (E) and PGE₂ (F) groups. Statistical analyses were done with one-way ANOVA (Brown–Forsythe and Welch tests). P values P < 0.05 are shown. Graphs without P values had no statistically significant differences.