Female gonads are the paired ovaries which produce eggs and female hormones.
Ovaries:
Ovaries are located in the pelvic part of the abdomen, one on each side of the uterus. A cross section of an ovary reveals rounded vesicles called follicles which are actual centres of egg production (oogenesis). Each follicle contains an immature egg called primary oocyte and follicles are always present in several stages of development. After the release of secondary oocyte (an egg) in the process called ovulation, the lining of follicle grows inward forming corpus luteum (yellow body) which serves as temporary endocrine tissue and continues to secrete the female sex hormones estrogen and progesterone.
Uterine tubes:
The paired tubes that receive the secondary oocyte from the ovary and convey it to the uterus are called uterine tubes. Feathery fimbriae fringe the part of the uterine tube that encircles the ovary. Each month as secondary oocyte is released, the motion of the fimbriae sweeps it across a tiny space between the uterine tube and the ovary into the tube.
The peristaltic contractions of the tube and the waving motion of the cilia in the mucous membrane of the tube carry the secondary oocyte along. Fertilization usually occurs in the uppermost third of the uterine tube. Zygote continues its journey toward the uterus where it will implant. The journey takes 4 – 7 days. If fertilization does not occur the secondary oocyte degenerates in the uterine tube.
Uterus:
The uterine tubes terminate in the uterus, a hollow muscular organ in front of rectum and behind urinary bladder. Uterus has three layers of tissues:
(1) The outer layer (perimetrium) extends beyond the uterus to form two broad ligaments that stretch from the uterus to lateral walls of the pelvis.
(2) Middle muscular layer (myometrium) makes up most of the uterine wall.
(3) Endometrium is the specialized mucous membrane that contains an abundance of blood vessels and simple glands. Uterus leads to cervix which leads to the vagina, a muscular tube 8 to 10 cm long. The wall of vagina is composed of smooth muscle elastic tissue.
External genitalia:
They include monspubis, labia majora, labia minora, vestibular glands, clitoris and vaginal opening. As a group of these organs are called the vulva.
Hymen:
In most young women vaginal opening is partially covered by a thin membrane, the hymen, which may be ruptured during normal strenuous activities or may be stretched or broken during sexual activity.
Mammary glands:
They are modified sweat glands that produce and secrete milk. They contain varying amount of adipose tissue. The amount of adipose tissue determines the size of the breasts, but the amount of mammary tissue does not vary widely from one woman to other.
Hormonal control of female reproductive organs:
The cyclical production of hormones controls the development of secondary oocyte in a follicle. Gonadotropin releasing hormone (GnRH) from Hypothalamus acts on the anterior pituitary gland which releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) to bring about the oocyte’s maturation and release from ovary. These hormones regulate
(1) Menstrual cycle which is the cyclic preparation of uterus to receive a fertilized egg, and
(2) The ovarian cycle, during which the oocyte matures and ovulation occurs. This monthly preparation continues upto age of 45 to 55 years of age, the ovaries lose their sensitivity to FSH and LH; they stop making normal amount of progesterone and estrogen. Menstrual cycle takes 28 days to complete one cycle. Hypothalamus releases on a regular cycle GnRH, which stimulates the anterior pituitary to secrete FSH and LH. FSH promotes the development of oocyte in one of the immature ovarian follicles. Follicles produce estrogen causing a build up and fertilization of endometrium and inhibition of FSH production.
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