Pregnancy-associated structural changes of the fallopian tube of rabbits with special reference to interstitial Cajal-like cells

The histological structure of the fallopian tube shows remarkable changes during pregnancy. Interstitial Cajal cell is known to play a key role in pacemaking motility in the gastrointestinal tract and the urinary tract. Its role in the motility of the fallopian tube is not fully explained. To describe the histological changes in the fallopian tube during early and late pregnancy, to shed light on the morphology of interstitial Cajal-like cells [ICLCs], and to localize their regional distribution in the fallopian tube in nonpregnant and pregnant rabbits. Thirty adult female rabbits were divided into three groups: group I [nonpregnant], group II [early pregnancy - day 4], and group III [late pregnancy - day 27]. The ampulla of the fallopian tube was excised and processed for histological, immunohistochemical, transmission, and scanning electron microscopy. In the nonpregnant group, it was found that the lining epithelium of the fallopian tube was composed of both ciliated and secretory cells. The ciliated cells were the major epithelial cell types; CD34-positive ICLCs were found maximally in the superficial zone of lamina propria, followed by musculosa, the deep portion of lamina propria, and least in serosa. The early pregnancy group showed a significant reduction in ciliated cells and an increase in secretory cells. In addition, there was a significant increase in the height of secretory cells and development of secretory organelles. There was a reduction in the number of CD34-positive ICLC in the superficial lamina propria compared with nonpregnant animals. The late pregnancy group showed an insignificant increase in ciliated cells and a decrease in secretory cells compared with group II. In addition, there was a decrease in the height of secretory cells and a reduction in their secretory organelles, but still more than that in group I. The structure of the fallopian tube showed histological changes during pregnancy. These changes represented a functional conditioning to the pregnancy state. ICLCs in the fallopian tube were prone to the same changes in their count and distribution