Granulated decidual cells in the mouse deciduoma: A putative source of decidual prolactin in mice

Decidual cells are endometrial fibroblasts that redifferentiate during preg nancy in several species of mammals. In this work, we describe a subpopulat ion of resident decidual cells in the mouse endometrium that are joined by intercellular junctions and have cytoplasmic granules. Decidualization was induced in pseudopregnant mice on the 4th day of pseudopregnancy by injecti on of 30 mul of arachis oil into the uterine lumen. The uteri were collecte d on day 8 of pseudopregnancy (at 4 p.m., 8 p.m. and 11 p.m.) and on day 9 (at 8 a.m.). The tissues were fixed for light and electron microscopy. Duri ng day 8 of pseudopregnancy, granulated cells were present at the antimesom etrial pole of the endometrium; they were concentrated at the periphery of the antimesometrial decidua and disappeared on day 9 of pseudopregnancy. Th e cytoplasm of the granulated decidual cells had acidophilic granules that stained also with periodic acid-Schiff (PAS). These granules stained with a nti-rat prolactin antibody in both light and electron microscope immunocyto chemical preparations. Vacuoles of various sizes were always present in the granulated cells. A PAS-positive and prolactin-stained material was often deposited at the periphery of the vacuoles. Our results indicate that the g ranulated decidual cells are the source of decidual prolactin which accumul ates in cytoplasmic granules. These granulated cells therefore form a trans ient gland in the mouse antimesometrial endometrium (granulated decidual gl and). Copyright (C) 2001 S. Karger AG,Basel.