The oviduct is divided into two distinct
histological and morphological sections. The isthmus has a more
muscular wall, is less winding and a smaller diameter than the ampulla.
The ampulla is very tortuous and lined with finger-like projections
called fimbria as it opens into the funnel shaped infundibulum at
the ovarian end of the oviduct. The junction between the ampulla
and isthmus is the site of fertilization. Ciliated epithelial cells,
found throughout the oviduct, are important in the movement of eggs
and sperm in the oviduct. Muscle contractions are also involved in
the movement of eggs and sperm. During estrus, the infundibulum
is in apposition to the ovulation fossa. The fimbria on the infundibulum
then pick up and direct the egg into the oviduct.