The Uterine Tubes

About the time of ovulation, the infundibulum, closest to the ovary, moves to cover the site of rupture of the mature (Graafian) follicle.  

The ovum moves down the infundibulum of the uterine tube toward the ampulla, assisted by peristaltic contractions of the smooth muscle in the wall of the tube as well as fluid moved by ciliated epithelial cells in the mucosa of the tube.  The ampulla is usually the site of fertilization.  

After fertilization, the embryo moves down through the isthmus which connects the uterine tube with the uterine horns or uterus.  The thick muscular wall of the isthmus of the uterine tube helps propel the embryo into the uterus where it can be nourished during further development.

1. tunica mucosa
2. tunica submucosa
3. tunica muscularis
4. tunica serosa.

The thickness and specific characteristics of these tunics varies with the region of the uterine tube. 
As always, structure reflects function.    all images below should be clicked to view micrographs

The tunica mucosa of the ampulla provides the proper environment for fertilization.

As a result, in the isthmus the tunica mucosa is reduced in thickness and the tunica muscularis is much thicker

The lamina epithelialis of the tunica mucosa of the uterine tubes is an intermittently ciliated columnar epithelium that contains two types of cells:  a ciliated cell and a non-ciliated, secretory cell.  In the cow and sow the lamina epithelialis may be pseudostratified intermittently ciliated columnar.  The secretory product of the non-ciliated, secretory cells is moved toward the uterine horns by the movement of the cilia on the ciliated cells.  This secretion probably also protects and nourishes the ovum.  

1. Note the extensive folding of the tunica mucosa which serves to increase the surface area providing large numbers of epithelial cells.
2. Higher magnification view of shaded area showing the extensive sheet of epithelial cells.
3. Higher magnification of shaded area showing a surface view of the intermittently ciliated columnar epithelium of the uterine tube.  Note the numerous ciliated cells that provide the movement of the male and female gametes to the site of fertilization.  Note the numerous non-ciliated secretory cells that provide nourishment to the ovum and zygote.  The size of non-ciliated secretory cells is under the control of progesterone.  With higher levels of progesterone, the non-ciliated cells become taller and have a greater secretory rate.

Click here to see SEM images of a uterine tube from a sow. 

1. Note the highly folded tunica mucosa and the relatively thin tunica muscularis (double arrows).  
2. Enlarged view of the shaded area in "A".  Note the appearance of the lamina epithelialis and the thin lamina propria.  
3. Enlarged view of shaded area in "B" showing the cells of the lamina epithelialis in longitudinal section.  Note that the epithelium consists of both ciliated and non-ciliated cells. 

Cyclic Changes in the Epithelium : Under the influence of estrogen, the ciliated epithelial cells increase in height and in the number of cilia.  Under the influence of progesterone, these cells decrease in height and in the number of cilia.   These cells are at their tallest with the most numerous cilia at the time of ovulation.  Their main function is to assist in the movement of the ovum toward the site of fertilization and the embryo toward the uterus.  This action is secondary to the peristaltic movement of the isthmus region.

Clinical:  The uterine tubes are the site of tubal ectopic pregnancies.  They can also be the site of bacterial infection which can lead to Pelvic Inflammatory Disease, a major cause of infertility in women.