Decidual cell reaction induced by prostaglandin F_2α in the mature oöphorectomized rat

Summary

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 mg of estradiol 17β 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<0.001) in weight was found in cornua that received PGF_2α (144 +- 6.7 mg), PGF_2α with mild local trauma (scratch) (146 +- 28.0 mg), and scratch alone (162 +- 12.7 mg). The majority of cornua treated by scratch alone, or by PGF_2α 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 OCR, the highest rank was found in tissues treated by scratch alone or by PGF_2α with or without scratch. Morphometric evaluation by light microscopy indicated that the extent of decidualization in PGF_2α-treated tissue was comparable to that of scratchtreated tissue. Ultrastructural observation of PGF_2α-treated tissue revealed that decidual cells closely resembled those treated with scratch. However, electron microscopic morphometry revealed that cells that responded to PGF_2α 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 PGF_2α can initiate, in the hormonally prepared mature oöphorectomized rat, a DCR comparable to that induced by local trauma.