The oviduct in cows has different types of cells in its different parts. The number of ciliated and non-ciliated cells changes during the estrous cycle. In the isthmus, fewer changes happen compared to the ampulla. The researchers used immunohistochemistry to study the cell types in the isthmus. They found that isthmus cells express FOXJ1 or PAX8, and the number of dividing cells (Ki67+) changes during the cycle. Some cells in the isthmus have both Ki67 and FOXJ1. These findings show that the isthmus has specific cell types different from the ampulla, which may affect how the oviduct functions.