Morphological changes in the smooth muscle cells of the mouse lower oviduct during pregnancy and post-partum.

The muscle coat of the lower region of the mouse oviduct undergoes morphological changes during pregnancy and post-partum. Ultrastructural examination and morphometrical findings show that, during pregnancy, the smooth muscle cells undergo a significant increase in both the number of mitochondria and caveolae and in the extension of the rough endoplasmic reticulum and Golgi apparatus, suggesting an enhancement of metabolic activities, especially protein synthesis. Within two days after delivery, the number of mitochondria and caveolae is similar to that of non-pregnant mice, whereas the extension of the rough endoplasmic reticulum and Golgi apparatus further increases significantly. The cytological signs of enhanced protein synthesis in the smooth muscle cells of the lower oviduct during pregnancy and, especially, in the post-partum period are probably related to a remodelling of the intercellular connective tissue matrix.