Ovulation: the female reproductive tract, the ovary, and the ovulatory follicle

Hello, my name is Diane Duffy. I'm a Professor, and the Vice Chair for Research in the Department of Physiological Sciences at Eastern Virginia Medical School in Norfolk, Virginia. My laboratory's research focuses on ovarian function, specifically on ovulation, which is the focus of this presentation. In my lab, we use non-human primates as well as cells and tissues from women, so most of the story I'll present today will be told from the perspective of the human or monkey ovary with some studies from other species to highlight key concepts.

In this presentation, we will cover the female reproductive tract and the ovary, the structural transformations of the ovulatory follicle, and the endocrine and paracrine control of ovulation. Let's get started with a brief tour of the female reproductive tract.

In women, the reproductive tract is located low in the pelvis. The uterus is central, and is composed primarily of the myometrium or uterine muscle, and the endometrium, which is where implantation occurs. The endometrium is the layer that undergoes extensive changes with each reproductive cycle. In fact, endometrial tissue in blood comprise the fluid that's passed each month at menstruation. The cervix is a dense fibrous structure at the distal end of the uterus, which connects to the vagina. The cervical canal permits menstrual fluid to pass through the cervix to the vagina, and also allow a sperm deposited in the vagina to transit to the uterus. Humans have two fallopian tubes, also called oviducts or uterine tubes. These tubes begin at the fundus or top of the uterus, and end at the ovary with a structure called the fimbria. The fimbria is physically attached to the surface of the ovary. The ovarian ligament connects the ovary to the body of the uterus. The blood ligament keeps the ovary, the fallopian tube, and the uterus in close contact. This image, taken during a laparoscopic surgical procedure shows the female reproductive tract. The dark rod is a surgical instrument being used here to elevate the uterus, and improve the view of other reproductive tract structures. At the top of the image is the abdominal body wall, and the white stripe is the bladder. Central in this image is the uterus with the fundus or top of the uterus closest to the camera. At the bottom of the image is bowel surrounded by intra-abdominal fat. You can see the fallopian tubes connecting to the uterine fundus on both sides of the uterus. The fallopian tube ends with an enlarged structure with finger-like projections, and this is the fimbria. Note how each fimbria surrounds, and almost cradles it's ovary, which is white in color. The ovary on the right side of the image gives the best view of the ligaments. The ovarian ligament is a string like structure that stretches from the ovary, and attaches to the uterus. The sheet-like blood ligament stretches from the uterus and behind the ovary to hold the uterus, ovary, and fallopian tubes together in the abdomen. Close proximity between these organs is important for efficient transit of the oocyte, also called an ovum or egg into the fimbria, and then onto the fallopian tube after ovulation.