Decidual cell reaction induced by prostaglandin F2 alpha in the mature oöphorectomized rat.

Sprague-Dawley rats were oöphorectomized and after a 2-3 week recovery period were given daily injections of progesterone (2.0 mg/0.1 ml) for six consecutive days. On the fourth day of progesterone treatment 0.2 microgram of estradiol 17 beta was given in addition and the right uterine cornua were subjected to one of five experimental maneuvers. On the sixth day of progesterone treatment the uterine cornua were weighed and processed for light and electron microscopy. The weights of all left cornua (84.6 +/- 3.7 mg) and the right cornua of PBS-injected (93.3 +/- 11.5 mg) and sham operated uteri (83.6 +/- 19.8 mg) were comparable. A significant increase (p less than 0.001) in weight was found in cornua that received PGF2 alpha (144 +/- 6.7 mg), PGF2 alpha with mild local trauma (scratch) (146 +/- 28.0 mg), and scratch alone (162 +/- 12.7 mg). The majority to cornua treated by scratch alone, or by PGF2 alpha with or without scratch, showed a decidual cell reaction by light microscopy and had a significantly higher mitotic index than those treated with saline, or by sham operation. When specimens were evaluated for the presence of the DCR, the highest rank was found in tissues treated by scratch alone or by PGF2 alpha with or without scratch. Morphometric evaluation by light microscopy indicated that the extent of decidualization in PGF2 alpha-treated tissue was comparable to that of scratch-treated tissue. Ultrastructural observation of PGF2 alpha-treated tissue revealed that decidual cells closely resembled those treated with scratch. However, electron microscopic morphometry revealed that cells that responded to PGF2 alpha had higher volume and surface densities of organelles associated with metabolic activity than did cells responding to scratch alone. These results demonstrate that locally administered PGF2 alpha can initiate, in the hormonally prepared mature oöphorectomized rat, a DCR comparable to that induced by local trauma.