ovary

Ovaries

Ovaries in the female called female gonads.

Paired oval bodies, pinkish grey 8n colour.

Size and Shape

Each ovary; 2.5-3.5cm long

2cm wide

1cm thick

Location

Ovaries are on the right and left sides of the uterus.

Located on shallow ovarian fossa on lateral wall of pelvic.

Each ovary is attached to the back side of each broad ligament by mesentery called mesovarium (fold of peritoneum) and to uterus by ovarian ligaments (thick border of mesovarium) and to lateral pelvic wall by suspensory ligament of the ovary (infundibulopelvic ligament; thin fold of peritoneum). 

Mesovarium contains veins, arteries, lymphatics and nerves to and from hilum (opening) of the overy.

Structure of Ovaries

1. Germinal epithelium

Layer of simple epithelium. It covers the surface of overy.

2. Tunica albuginea

Whitish capsule of dense, irregular connective tissue located immediately deep to germinal epithelium.

3. Stroma

Mass of connective tissue deep to tunica albuginea.

Composed of two parts;

a. Cortex

Cortex is outer part of overy, contains ovarian follicles at various stages of development and corpus luteum. Each follicle contains one oocyte.

b. Medulla 

Medulla is inner, loose vascular layer of ovary contains blood vessels, nerves and lymphatics vessels.

Ovarian Follicles

Round epithelial vesicles are follicles.

Ovarian follicles stage of development throughout cortex.

A follicle is a small sac of fluid in the ovaries that contains a developing egg. 

Women begin with about 300,000 to 400,000 eggs till puberty.

At puberty age to reproductive age (13-46 years of age) 400 to 500 eggs (primordial follicle) present and remaining follicle degenerate.

Total of 400-500 oocytes are ovulated in reproductive life.

Gametes

Referrs sex cells, Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes are haploid cells.

Oocytes

Immature egg cell or ovum.

Oogenesis

Process of formation of female gametes. Haploid cells.

Ovum

Egg cell.

Ovulation

Process in which a mature egg is released from the ovary. 

Zygote

Fertilized egg cell; union of female gamete (egg, or ovum) with a male gamete (sperm).

Gonads; the primary reproductive organs, are the testes in the male and the ovaries in the female. 

Follicle 

A small, fluid-filled sac in the ovary that contains one immature egg.

Primordial follicles

Primordial follicle has small oocyte surrounded by follicular cells (granulosa cells).

Primary follicle (preantral)

Primary follicle has a larger oocyte than the primordial follicle and is surrounded by granulosa cells. Zona pellucida is present in the primary follicles.

Secondary follicles (antral)

Primary follicle has matured into a secondary follicle. 

Graaphian (mature) follicles; vesicular follicle 

Mature ovarian follicle is known as the graafian follicle. It contains secondary oocyte.

Vesicular follicles almost ready to release secondary oocyte (called ovum) in process called ovulation.

Graafian follicle ruptures to release the secondary oocyte, in a process known as ovulation.

Corpus luteum

Corpus luteum contains residue of mature follicles after ovulation.

Corpus albicans

Corpus luteum degenerates into a fibrous scar tissue called corpus albicans.

Spermatogenesis

Process of sperm cell development. Haploid cells.

Gametogenesis

Spermatogenesis and oogenesis are term as gametogenesis.

Ovarian Hormones

1. Estrogen

Ovarian Follicle secreting oestrogen.

2. Progesterone

Corpus luteum secreting mainly progesterone.

3. Inhibin

4. Relaxin 

1. Estrogen

Estrogen is secreted by cells in wall of ovarian follicles (growing grafian follicle).

Function of Estrogen

1. Promote development of female reproductive tract. 

2. Development and maintenance of secondary sex characteristics; breast.

3. Secreted by ovaries prior to ovulation.

4. Calcium hemostasis.

5. Build uterine lining

6. Estrogens are produced primarily in the ovaries, corpus luteum, and placenta by during pregnancy.

2. Progesterone

Progesterone is produced by corpus luteum.

1. Prepare the uterus for pregnancy. 

2. Secreted by ovaries after ovulation.

3. Thickening of functional layer of of endometrium (uterine line).

4. Prepare the endometrium for implantation of fertilized ovum and mammary glands for milk secretion.

5. High level of progesterone inhibit GnRH (gonadotropin releasing hormone); LH, FSH hormone.

3. Inhibin

Inhibin is secreted by corpus luteum of overy.

Inhibin decreases secretion of FSH, and LH.

4. Relaxin

Produced by corpus luteum and also produced by placenta,chorion, decidua during last trimester of pregnancy.

This hormone loosens and relaxes muscles, joints and ligaments during pregnancy to help body stretch.

Function of Ovaries

1. Production of gametes (ova, egg).

2. Process which results in production of an ovum is called oogenesis.

3. Release of ovum is called ovulation.

4. Secretion of female hormones; estrogen and progesterone are secreted by cells of ovarian tissues. Help in regulating reproductive function in female and development of secondary sex characteristics and regulate ovarian cycle, menstrual cycle (uterine cycle) and pregnancy.