Time course major events in development and differentiation of the rat male reproductive system. Although efferent ductules were emphysized for ESR1 expression, epididymal epithelium has positive expression in select cell types (see section 3). MT, mesonephric tubules; AR, androgen receptor; ESR, estrogen receptor; WD, Wolffian duct; T, testosterone; E2, estrogen; FSH, Follicle Stimulating Hormone; LH, Luteinizing Hormone; ED, efferent ductules; RT, rete testis. Adapted from Hinton & Avellar (2018).