Histology and prostate specific antigen (PSA) staining of 200-day human prostate xenografts exposed to varying initial (corn-oil or estradiol) and later-life (control placebo capsules or estrogen pellets and testosterone capsules) exposures.

<p>(<b>A</b>) Control human prostate xenografts (control/control) contained phenotypically normal prostatic ducts surrounded by mature stromal cells, (<b>E</b>) with proper PSA staining in the luminal cells of ducts. (<b>B</b>) Human prostate xenografts given an initial treatment of estrogen, with no subsequent treatment (estrogen/control) demonstrated a mature phenotype containing both nicely developed glands and a normal cellular stroma, (<b>F</b>) with normal PSA staining similar to C/C-treated xenografts. (<b>C</b>) In comparison, xenografts given only a secondary treatment of estrogen and testosterone (control/estrogen), appeared to have areas of immature or undeveloped tissue (<b>G</b>) with a greater amount of PSA staining in the lumen compared to C/C-xenografts. (<b>D</b>) An initial and secondary exposure to estrogen (estrogen/estrogen) exhibited an extensive amount of glandular hyperplasia (*), (<b>H</b>) as well as a significant amount of PSA staining. Figure headings represent treatment conditions as initial/secondary exposure. (<b>A-H</b>) Gestational age of human fetal prostate before implantation is 20 weeks. (Hematoxylin and Eosin staining and counter-stain; scale bar = 50 μm).