Question

ovulation occurs when the oocyte is released into the peritoneal cavity .How does it usually enter the uterine tube?(identify the main organs and briefly explain their function)

Answer 1

The ovaries are not linked to the uterine/fallopian tube directly. However, fertilization of ovum/egg occurs in uterine tube. Hence, the egg has to be picked up by the uterine tube upon ovulation. The ovaries are attached to uterus via the utero ovarian ligament. Ovaries are however not linked to uterine tube. Instead they are linked to sidewall of pelvic cavity by the infundibulopelvic ligament. This ligament also is associated with ovarian blood vessels. There are two fallopian tubes in each women linked to the sides of the uterus. Any fallopian tube can pick up the ovum from either ovary present.

The uterine tube is made up of three parts- Infundibulum, Isthmus and Ampulla. Uterine tube has three layers-a smooth muscle layer, a mucosal layer and a serosal layer. The tubes have a central lumen as well. In the mucosa, there are epithelial cells, lamina propria and the basement membrane. Epithelial cells are ciliated, intercalated cells and Peg cells.

Fimbriae are small fingerlike projection present at the proximal end of infundibulum. It is the fimbriae that pick up the ovum that is released from the dominant follicle of ovaries after ovulation. However, there is no direct contact of the fimbriae with the ovaries. Fimbriae are closest to the ovary. When the follicle releases the ovum, it is surrounded by the zona pellucida and granulosa cells. The ovum is released in the peritoneal cavity at the surface of the ovary. Prior to ovulation, the epithelial cells in the fimbriae will exhibit cilia on their surface. The smooth muscle activity in the uterine tube also increases. When ovulation occurs, the fimbriae of the uterine tube will move towards the ovary. They will initiate rhythmic movements over the surface of the ovary. These movements of the fimbriae cause generation of currents in the peritoneal fluid. These rhythmic currents along with the ciliary movement generated, will then capture the ovum complex that is released in pelvic cavity and move it into the uterine tube.

Ampulla is the next region where fertilization occurs if sperm is present. Isthmus is the reservoir for sperm till it can fertilize the ovum when it enters the fallopian/uterine tube. Ovum moves through the fallopian tube via ciliary movement across the tube