Histological examination of xenotransplanted human endometrial tissues.

<p>(<b>A</b>) Human endometrial tissues before transplantation. Endometrial tissues showed simple columnar epithelium and dense stroma, which characterized a typical human early proliferative phase endometrium. (<b>B</b>) Control group without hormone treatment. The tissue fragments were small in size and increased in lumen diameter. (<b>C</b>) 14d group (E₂ provided alone). Glandular epithelium was in high columnar form with a significant pseudostratification of the nuclei. (<b>D</b>) 21d group (E₂ provided for 21 days of which P₄ provided for last 7 days). Glandular epithelial cells were changed into low columnar. Subnuclear vacuolation was clearly visible in the glandular epithelial cells with nuclei close to the basilar membrane, whereas stromal cell density was decreased. (<b>E</b>) 28d group (E₂ provided for 28 days of which P₄ provided for last 14 days). The cell-cavity surface with irregular margins contained a large number of small secretion bubbles. Interstitial edema was observed, stromal cells were enlarged, and the nuclei clearly showed a typical decidual-like stromal change. (<b>F</b>) 31d group (hormones were provided for 28 days and then no hormone support for the remaining 3 days). A large number of leukocytes were infiltrated, and the endometrial tissue structure was disintegrated with erythrocyte leakage. Original magnification: 400× (H&E).