What is the structure of the ovaries

what is the structure of the ovaries

The ovaries are paired, oval organs attached to the posterior surface of the broad ligament of the uterus by the mesovarium (a fold of peritoneum, continuous with the outer surface of the ovaries). Neurovascular structures enter the hilum of the ovary via the /5(84). Jan 21,  · Ovary The ovary is a ductless reproductive gland in which the female reproductive cells are produced. Females have a pair of ovaries, held by .

The primary female reproductive organs, or gonads, are the two ovaries. Each ovary is a solid, ovoid structure about the size and shape of an almond, about 3. The ovaries are located in shallow depressions, called ovarian fossaeone on each side of the uterusin the lateral walls of the pelvic cavity. They are held loosely in place by peritoneal ligaments.

The ovaries are covered on the outside by what is the structure of the ovaries layer of simple cuboidal epithelium called germinal ovarian epithelium. This is actually the visceral peritoneum that envelops the ovaries. Underneath this layer is a dense connective tissue capsulethe tunica albuginea. The substance of the ovaries is distinctly divided into an outer cortex and an inner medulla.

The cortex appears more what is a manic state of mind and granular due to the presence of numerous ovarian follicles in various stages of development. Each of the follicles contains an oocytea female germ cell.

The medulla is a loose connective tissue with abundant blood vessels, lymphatic vessels, and nerve fibers. Female sex cells, or gametes, develop in the ovaries by a form of meiosis called oogenesis. The sequence of events in oogenesis is similar to the sequence in spermatogenesisbut the timing and final result are different.

Early how to get rid of old dark scars on legs fetal development, primitive germ cells in the ovaries differentiate into oogonia. These divide rapidly to form thousands of cells, still called oogonia, which have a full complement of 46 23 pairs chromosomes. Oogonia then enter a growth phase, enlarge, and become primary oocytes. The diploid 46 what is the edt now primary oocytes replicate their DNA and begin the first meiotic division, but the process stops in prophase and the cells remain in this suspended state until puberty.

Many of the primary oocytes degenerate before birth, but even with this decline, the two ovaries together contain approximatelyoocytes at birth. This is the lifetime supply, and no more will develop.

This is quite different than the male in which spermatogonia and primary spermatocytes continue to be produced throughout the reproductive lifetime. By puberty the number of primary oocytes has further declined to aboutBeginning at pubertyunder the influence of follicle-stimulating hormoneseveral primary oocytes start to grow again each month.

One of the primary oocytes seems to outgrow the others and how to build a kitchen counter resumes meiosis I. The other cells degenerate. The large cell undergoes an unequal division so that nearly all the cytoplasmorganelles, and half the chromosomes go to one cell, which becomes a secondary oocyte.

The remaining half of the chromosomes go to a smaller cell called the first polar body. What is the structure of the ovaries secondary oocyte begins the second meiotic division, but the process stops in metaphase. At this point ovulation occurs. If fertilization occurs, meiosis II continues.

Again this is an unequal division with all of the cytoplasm going to the ovum, which has 23 single-stranded chromosome. The smaller cell from this division is a second polar body. What is the structure of the ovaries first polar body also usually divides in meiosis I to produce two even smaller polar bodies. If fertilization does not occur, the second meiotic division is never completed and the secondary oocyte degenerates. Here again there are obvious differences between the male and female.

In spermatogenesis, four functional sperm develop from each primary spermatocyte. In oogenesis, only one functional fertilizable cell develops from a primary oocyte. The other three cells are polar bodies and they degenerate. An ovarian follicle consists of a developing oocyte surrounded by one or more layers of cells called follicular cells. At the same time that the oocyte is progressing through meiosis, corresponding changes are taking place in the follicular cells.

Primordial follicles, which consist of a primary oocyte surrounded by a how to act older than you are layer of flattened cells, develop in the fetus and are the stage that is present in the ovaries at birth and throughout childhood. Beginning at puberty, follicle-stimulating hormone stimulates changes what does c3 mean on a bearing the primordial follicles.

The follicular cells become cuboidal, the primary oocyte enlarges, and it is now a primary follicle. The follicles continue to grow under the influence of follicle-stimulating hormone, and the follicular cells proliferate to form several layers of granulose cells around the primary oocyte. Most of these primary follicles degenerate along with the primary oocytes within them, but usually one continues to develop each month.

The granulosa cells start secreting estrogen and a cavity, or antrumforms within the follicle. When the antrum starts to develop, the follicle becomes a secondary follicle. The granulose cells also secrete a glycoprotein substance that forms a clear membranethe zona pellucida, around the oocyte. After about 10 days of growth the follicle is a mature vesicular graafian follicle, which forms a "blister" on the surface of the ovary and contains a secondary oocyte ready for ovulation.

Ovulation, prompted by luteinizing hormone from the anterior pituitary, occurs when the mature follicle at the surface of the ovary ruptures and releases the secondary oocyte into what is the structure of the ovaries peritoneal cavity. The ovulated secondary oocyte, ready for fertilization is still surrounded by the zona pellucida and a few layers of cells called the corona radiata. If it is not fertilized, the secondary oocyte degenerates in a couple of days.

If a sperm passes through the corona radiata and zona pellucida and enters the cytoplasm of the secondary oocyte, the second meiotic division resumes to form a polar body and a mature ovum. After ovulation and in response to luteinizing hormone, the portion of the follicle that remains in the ovary enlarges and is transformed into a corpus luteum.

The corpus luteum is a glandular structure that secretes progesterone and some estrogen. Its fate depends on whether fertilization occurs. If fertilization does not take place, the corpus luteum remains functional for about 10 days; then it begins to degenerate into a corpus albicans, which is primarily scar tissueand its hormone output ceases.

If fertilization occurs, the corpus luteum persists and continues its hormone functions until the placenta develops sufficiently to secrete the necessary hormones. Again, the corpus luteum ultimately degenerates into corpus albicans, but it remains functional for a longer period of time.

Blood supply and innervation

Mar 03,  · Ovaries have three layers. The outer layer consists of cuboidal epithelium, a type of tissue that lines most organs of the body. Under that is the tunica albuginea, a layer of connective tissue made of collagen. The innermost layer is the cortex and contains the ovarian follicles. Ovarian structure The female gonads, or primary sex organs, corresponding to the testes in a male, are the two ovaries. Each is suspended by a mesentery, or fold of membrane, from the back layer of the broad ligament of the uterus.

The ovary is the gonadal organ primary sexual organ in females. There are two ovaries located within the pelvic cavity, on either side of the uterus. Picture 1: Location of the ovaries in relation to other organs of the female reproductive system.

The ovaries are almond-shaped structures located on either side of the uterus, and closely related to several anatomical structures in the pelvic region. Each ovary has average dimensions of 3 cm length , 2 cm breadth , and 1 cm thickness ; hence being smaller than its male analogue — the testis. The ovaries lie almost vertically in the upright position, and have their upper poles tilted slightly laterally facing the fimbriae at the end of the uterine tubes fallopian tubes.

The lower pole is directed towards the wall of the uterus, and is attached to the uterine wall by the ovarian ligament. The anterior border of the ovary is attached to a double fold of peritoneum extending from the posterior leaf of the broad ligament. This peritoneal extension is called the mesovarium. The rest of the ovarian surface is devoid of peritoneal attachment or lining. The lateral surface of the ovary is attached to the suspensory ligament of the ovary which extends from the wall of the pelvic cavity and carries the blood vessels, lymphatics, and nerves supplying the ovary.

Each ovary is said to be located in close relation laterally to the ovarian fossa which is a small oval depression in the pelvic wall — marked anteriorly by the external iliac artery, posteriorly by the internal iliac artery and the ureter , and containing the obturator nerve within it.

The ovary is covered by a thick fibrous capsule called tunica albuginea , the outer surface of which is lined by a single layer of cuboidal epithelium which has a misleading name — the germinal epithelium. Inner to the tunica albuginea, the ovarian tissue is divided into two regions; a centrally located medulla and a peripheral cortex.

The medulla contains blood vessels, lymphatics and nerves of the ovary. The cortex is made up of ground substance that accommodates a huge number of primordial follicles and the various developing stages of these follicles; primary follicles, secondary follicles, and tertiary Graafian follicles. The cortex also contains the remnant tissues following ovulation cyclic release of ova from the ovaries to the abdominal cavity ; the corpus luteum and corpus albicans.

Ovaries receive their blood supply via ovarian arteries which arise from the abdominal aorta slightly below the level of renal articles L2 vertebral level. These arteries pass inferolaterally beneath the peritoneum of the posterior abdominal wall, on the psoas major muscle, and cross the pelvic brim and bend medially to traverse through the suspensory ligament and reach the ovary.

They also give off a tubular branch to supply the lateral end of the uterine tubes. The venules of the ovary join together in the medulla and move through the mesovarium and suspensory ligament as a pampiniform plexus which joins to form a pair of veins on either side, and then form a single ovarian vein on either side.

The right ovarian vein drains directly to the inferior vena cava, and the left ovarian vein to the left renal vein. Lymphatic vessels follow the venous drainage and drain to the para-aortic nodes situated alongside the aorta close to L2 vertebral level. Nerve supply is derived from the T10 spinal segment, via the autonomic nerves of aortic and inferior hypogastric plexuses.

The ovaries develop from a condensed region in the embryonic gonadal ridge just medial to the mesonephros, in a manner similar to the testes. Primordial germ cells from the embryonic yolk sac move towards the gonadal region and join the developing gonads. Initially the ovaries are located in the posterior abdominal wall, and they later descend together with their blood and nervous supply.

This descent is guided by a condensed mesenchymal tissue named gubernaculum. The ovaries do not descend as far below as the gubernaculum, and are instead arrested inside the pelvis , by the sides of the uterus. The gubernaculum extends further below forming its remnant structures — the round ligament of the uterus and the ovarian ligament — and attaches itself to the labia majora part of female external genitalia.

The mesonephric ducts and tubules usually disappear in females, but their remnants may be found in between the layers of the broad ligament. The ovary is the primary reproductive organ gonad in females, and has two main functions which are i Maturation and release of female gametes ova in a periodic manner, and ii Secretion of female sex hormones mainly estrogen and progesterone.

The ovaries contain about one million primordial follicles primary oocytes surrounded by epithelium by the time of birth.

Most of these follicles degenerate and only about 40, remain at the time of puberty. Small groups of these follicles begin to mature in a cyclic manner under the influence of FSH Follicular Stimulating Hormone following puberty.

Only one follicle undergoes complete maturation in a given cycle, and the others gradually degenerate. The primordial follicle progressively develops into a primary follicle, a secondary antral follicle, and a tertiary Graafian follicle. During this development, fluid accumulation and granulosa cell formation occurs around the oocyte. The mature Graafian follicle contains the primary oocyte which divides by meiosis to form the secondary oocyte which is released to the abdominal cavity during ovulation that occurs during the 14th day of the menstrual cycle.

The Graafian follicle ruptures, and the released oocyte is held by the fimbriae finger-like projections at the end of the uterine tubes. The oocyte is then transported towards the body of the uterus, along the uterine tube, intended for fertilization with a male gamete sperm. The remnant tissue following the rupture of the Graafian follicle organizes into a yellow colored mass named corpus luteum.

The corpus luteum either persists if fertilization and implantation occurs i. Estrogen is the primary female sexual hormone, and is synthesized and released mainly by the granulosa cells of developing follicles within the ovaries.

Estrogen has the effect of developing female secondary sexual characteristics after puberty, and causes further development and maturation of female reproductive organs such as the vagina, uterus, and breasts. Progesterone is secreted mainly by the corpus luteum within the ovaries.

This hormone is mainly responsible for preparing the uterus for pregnancy. It also causes development and maturation of female reproductive organs. Ovarian cysts are fluid filled cystic spaces found within or on the ovary, usually due to accumulation of fluid around developing follicles. Functional ovarian cysts occur as part of the normal development of follicles, and are usually harmless and regress spontaneously.

Pathological ovarian cysts may occur due to an underlying abnormality in the ovary, with most of the cases being benign non cancerous. Ovarian cysts may cause abdominal or pelvic symptoms only when they are very large or become ruptured; in other instances they are asymptomatic and found incidentally during ultrasound scanning. Ovarian cancer is one of the most common gynecological cancers.

It usually occurs in older women above 50 years who have attained menopause. The exact cause is unknown, but the risk of ovarian cancer increases with age, positive family history, being overweight, and presence of other conditions such as endometriosis presence of parts of uterine inner tissues outside the uterus.

It may present with abdominal or pelvic symptoms due to irritation or compression of structures surrounding the ovary. Go search. Ovary The ovary is the gonadal organ primary sexual organ in females. Picture 1: Location of the ovaries in relation to other organs of the female reproductive system Structure of the Ovary Contents Structure of the Ovary Development of the Ovary Function Clinical significance.

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