Ovary – Tutorial
Please read Unit 13 – Introduction to Female Reproductive System Tissues prior to completing the activities in this chapter.
Introduction to the Ovaries
The ovaries are a pair of female gonads that serve to produce immature eggs called oocytes by the process of oogenesis which occurs within egg-producing structures known as ovarian follicles. The cells of ovarian follicles that surround developing oocytes also serve to secrete female sex hormones known as estrogens. After an oocyte is ovulated from an ovarian follicle, the remaining follicle becomes an endocrine structure known as the corpus luteum that secretes the hormone progesterone.
The ovaries are oval-shaped organs with a bumpy external surface measuring approximately 2 inches (5 cm) long and 1 inch (2.5cm) wide and suspended by mesenteric ligaments just lateral to each side of the uterus in the lower abdominopelvic cavity. The fimbriae of the oviducts (fallopian tubes) partially wrap around the surface of the ovaries so that an oocyte can be swept into the lumen of the oviduct after it is ovulated.
The ovaries are surrounded by a germinal epithelium which is simply the visceral peritoneum comprised of tall cuboidal (or short columnar) epithelial cells. Just under the germinal epithelium is a layer of dense connective tissue known as the tunica albuginea. Internally, ovarian tissue is divided into a superficial outer cortex where ovarian follicles are located and an inner medulla that is packed with connective tissue, lymphatic vessels, blood vessels, and nerve fibers.
As stated above, immature eggs known as oocytes develop inside ovarian follicles by the process of oogenesis. Each ovarian follicle contains a developing oocyte that is in the process of dividing by meiosis to eventually become an egg with 23 chromosomes after it is ovulated and fertilized by a sperm. Ovarian follicles progress through a series of developmental stages as they progress toward ovulation. The order of these developmental stages from primitive to advanced is as follows: primordial follicle, primary follicle, secondary follicle, and tertiary follicle (Graafian follicle, vesicular follicle). The tutorials that follow will focus primarily on the structure and function of each of these follicular stages.
Tutorial: Use the image slider below to learn more about the structure and characteristics of the ovaries.
Microscopy: Use the image slider below to learn how to use a microscope to study an ovary on a microscope slide.
