Reversibility of T-induced estrous cycle changes after T cessation. (A) Mice were subcutaneously implanted with a placebo (control) or T enanthate pellet at week 0, which was then removed after 6 weeks. Longitudinal weekly T levels were measured before pellet implantation (week 0), during T therapy (weeks 1–6) and following pellet removal (weeks 7–9) (mean ± SD, error bars shorter than symbol not shown, arrow points to subcutaneously implanted pellet). (B) All mice treated with T pellets at week 0 stopped cycling and demonstrated persistent diestrus until pellet removal at week 6, at which point estrous cyclicity resumed. (C) Two representative mice implanted with T pellets showed persistent diestrus during T therapy and prompt resumption of cyclicity following pellet removal, while two representative control mice continued cycling throughout the study (E = estrus, M = metestrus, D = diestrus, P = proestrus). Green shaded rectangle highlights 6 weeks of T therapy and purple shaded rectangle highlights 3 weeks following T cessation.