A Study on Morphological and Immunohistochemical Changes of the Myometrium in the Pregnant and Postpartum Rat

Han, Hyuck Dong; Yang, Young Cheoul; Bae, Ki Won

Abstract

This experiment was performed to investigate morphological and immunohistochemical changes of the connective tissue, the nerve and the smooth muscle cell in the pregnant and postpartum rat myometrium. The materials were the non-pregnant control, the 2-, the 4-, the 10-day gestation and the 1-, the 2-, the 6-day birth of rat myometrium. The light microscopic findings were examed after van Gieson and malachite green stainings. The reaction of nitric oxide synthase activity, apoptosis, type IV collagen, and estrogen receptor were examined immunochemically. The results were as follows: A. Light microscopic findings: 1. In the van Gieson staining for collagen fibers and smooth muscles, it showed the increase of pinky collagen fibers and yellow smooth muscle cells from the 2-day gestation. At the 1-day birth, the yellow hypertrophic smooth muscle cells were in the form of the papilla. The collagen fibers of the 2-day birth were more abundant than that of the 1-day birth. 2. In the malachite green staining for nerve fibers, it showed the blue spots. The size of spots of the 4-day gestation enlarged and at the 10-day gestation the number of fine spots was increased. At the 1-day birth, it showed the decreased number and increased size of spots. B. Immunohistochemical findings : 1. The NOS activity showed the increased positive reaction at the 2-day gestation. At the 10-day gestation, the outer zone of myometrium showed prominent positive. At the 1-day birth, the endothelium of the vessels were weakly positive. 2. The apoptotic reaction was localized at the connective tissue cells between the outer and inner zones of myometrium. The positive reaction cells were a few at the 1-day birth, several at the 2-day birth, and many at the 6-day birth. 3. The type IV collagen reaction appeared at the perivascualr area and the comnnective tissues of the inner zone. The positive reaction showed weak at the control, moderate at the 2-day gestation, and strong at the 4-day gestation. At the 1- and 2-day birth, the connective tissue of inner zone was moderately positive. 4. The estrogen receptor reaction cells appeared at the papillary outer zone of the 10-day gestation. The reaction cells were several at the 1-day birth and a few at the 2-day birth. C. Electron microscopic findings : 1. At the 10-day gestation, one group of smooth muscle cells had well-developed sarcoplasmic reticulum and the other group with abundant mitochondria appeared. At the 2-day birth, one group smooth muscle cells had degenerating processes and the other group with the serrated processes showed. At the 6-day birth, smooth muscle cells were degenerated. 2. Mitochondria were abundant in the smooth muscle cell with many processes of the 10-day gestation. The onset of mitochondrial degeneration began at the 2-day birth. The mean section of mitochondria was increased by the 2-day birth and markedly decreased at the 6-day birth. 3. At the 1-day and 2-day birth, the electron-dense region of cell membrane was increased and submembranous caveolae were decreased. The mean section of caveolae was the mostly decreased at the 10-day gestation, nearly restored at the 1-day birth and enlarged at the 6-day birth.