Effect of pregnancy on endometriotic lesion histology.

Mice with surgical induced endometriosis were mated and sacrificed at day 18 of pregnancy. Micrographs show representative histological sections of endometriotic lesions from non pregnant (A-C) and pregnant mice (D-I). Asterisks show necrotic zones and black arrows infiltrated zones, both characterized by the presence of inflammatory cells. White arrows indicate a decidualized stroma, characterized by the presence of large polygonal cells with a pale pink cytoplasm and a large round or oval nucleus. Arrowheads show endometrial involution, recognized by the presence of a flattened-glandular-epithelium or the lack of one. The white boxes are shown at a higher magnification to the right. (A, D, G: 40X; B, E, H: 100X; C, F, I: 400X). Scale bar indicates 100 μm.