biology

Ovary

Ovary is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Ovary rather than just read about it. In short: The ovary (from Latin ōvārium 'egg') in the human female reproductive system is a gland that produces female sex hormones, and also controls the development and release of the egg cell (the female gamete). The ovarian follicles also produce and secrete inhibin to suppress the action of follicle stimulating hormone released by the anterior pituitary.

Key takeaways

Ovary belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ovary to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ovary from memory before moving on to harder problems.

Reference excerpt

The ovary (from Latin ōvārium 'egg') in the human female reproductive system is a gland that produces female sex hormones, and also controls the development and release of the egg cell (the female gamete). The ovarian follicles also produce and secrete inhibin to suppress the action of follicle stimulating hormone released by the anterior pituitary. The paired ovaries are located one on either side of the uterus, and connect with the uterus through the fallopian tubes. They are held in place by the ovarian ligament, and the suspensory ligament of the ovary. The ovary progresses through many stages beginning in the prenatal period through menopause.

Structure Each ovary measures around 3 cm in length by 1.5 cm wide and is 1 cm thick, and sits in a depression in the lateral wall of the pelvic cavity. This depression is called the ovarian fossa and measures around 4 cm x 3 cm x 2 cm. The fossa is bounded above by the external iliac artery and vein, in front by the obliterated umbilical artery, and behind by the ureter. Each ovary is surrounded by a capsule, and has an outer cortex and an inner medulla. The capsule is of dense connective tissue and is known as the tunica albuginea. Usually, ovulation occurs in one of the two ovaries, releasing an egg each menstrual cycle. The side of the ovary closest to the fallopian tube is connected to it by suspensory ligament, and the other side points downwards attached to the uterus via the ovarian ligament. Other structures and tissues of the ovaries include the hilum.

Ligaments The ovaries lie within the peritoneal cavity, on either side of the uterus, to which they are attached via a fibrous cord called the ovarian ligament. The ovaries are uncovered in the peritoneal cavity but are tethered to the body wall via the suspensory ligament of the ovary, which is a posterior extension of the broad ligament of the uterus. The part of the broad ligament of the uterus that covers the ovary is known as the mesovarium. The ovarian pedicle is made up of the fallopian tube, mesovarium, ovarian ligament, and ovarian blood vessels.

Microanatomy The surface of the ovaries is covered with ovarian surface epithelium, also called germinal epithelium, a membrane consisting of a lining of simple cuboidal-to-columnar shaped mesothelium.

The outer layer is the ovarian cortex, consisting of ovarian follicles and stroma in between them. Included in the follicles are the cumulus oophorus, membrana granulosa (and the granulosa cells inside it), corona radiata, zona pellucida, and primary oocyte. Theca of follicle, antrum and follicular fluid are also contained in the follicle. Also in the cortex is the corpus luteum, derived from the follicles. The innermost layer is the ovarian medulla. It can be hard to distinguish between the cortex and medulla, but follicles are usually not found in the medulla. Follicular cells are flat epithelial cells that originate from the surface epithelium covering the ovary. They are surrounded by granulosa cells that have changed from flat to cuboidal and proliferated to produce a stratified epithelium. The ovary also contains blood vessels and lymphatics.

Function At puberty, the ovary begins to secrete increasing levels of hormones. Secondary sex characteristics begin to develop in response to the hormones. The ovary changes structure and function beginning at puberty. Since the ovaries can regulate hormones, they also play an important role in pregnancy and fertility. When egg cells (oocytes) are released from the fallopian tube, a variety of feedback mechanisms stimulate the endocrine system, which causes hormone levels to change. These feedback mechanisms are controlled by the hypothalamus and pituitary glands. Messages or signals from the hypothalamus are sent to the pituitary gland. In turn, the pituitary gland releases hormones to the ovaries. From this signaling, the ovaries release their own hormones.

Gamete production

The ovaries are the site of production and periodical release of egg cells, the female gametes. In the ovaries, the developing egg cells (or oocytes) mature in the fluid-filled follicles. Typically, only one oocyte develops at a time, but others can also mature simultaneously. Follicles are composed of different types and numbers of cells according to the stage of their maturation, and their size is indicative of the stage of oocyte development. When an oocyte completes its maturation in the ovary, a surge of luteinizing hormone is secreted by the pituitary gland, which stimulates the release of the oocyte through the rupture of the follicle, a process called ovulation. The follicle remains functional and reorganizes into a corpus luteum, which secretes progesterone to prepare the uterus for an eventual implantation of the embryo.

Hormone secretion At maturity, ovaries secrete estrogen, androgen, inhibin, and progestogen. In women before menopause, 50% of testosterone is produced by the ovaries and released directly into the blood stream. The other 50% of testosterone in the bloodstream is made from the conversion of the adrenal pre-androgens (DHEA and androstenedione) to testosterone in other parts of the body. Estrogen is responsible for the appearance of secondary sex characteristics for females at puberty and for the maturation and maintenance of the reproductive organs in their mature functional state. Progesterone prepares the uterus for pregnancy and the mammary glands for lactation. Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Ovary

Start with the simplest possible case. Write down what Ovary claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Ovary before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Ovary ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Ovary

In research: Ovary appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Ovary in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Ovary is common in secondary-school and first-year university syllabi. It links to neighbouring topics Endocrine system, Gynaecology, Human female reproductive system, so understanding it makes those chapters shorter.
In everyday life: Look for Ovary outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Ovary in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ovary means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Ovary out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ovary in simple terms?

Why does Ovary matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Ovary?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Ovary.