FEMALE REPRODUCTIVE SYSTEM

The female reproductive system consists of:

1) Ovaries

2) The ducts (oviduct, uterus, cervix, vagina)

1. Ovaries

A pair of ovaries present in peritoneal cavity. Ovaries have a group of cells called ovarian folicle that has developing Oocyte.

Function

Oogenesis

The formation of ovam in ovaries is called Oogenesis. The ovaries have specialized diploid germ cells, which undergo mitosis to large number of "Oogonia" which then form "Primary oocyte" that is then enclosed in a group of cells called "Follicle cells" which provide support and nutrition to the developing eggs. The ovam matures within the follicle by starting its meiosis.

The "Primary oocyte" undergoes meiosis 1 to form. "Secondary Oocyte" and a smaller "Polar body". "Meiosis II" continued up to Metaphase II in folicle cells, but is arrested up to the fertilization. In human female one secondary Oocyte is releastd in each menstrual cycle. This release of ovum (secondary oocyte) is called "ovulation". If the secondary oocyte is fertilized by sperm in oviduct, then it starts Meiosis II and form Ovum and another Polar body. The nucleus of ovam and sperm unite to form a diploid

"Zygote" that is carried to uterus for further nourishment.

2)The Ducts

The ducts of female reproductive system includes

i) Oviduct

ii) Uterus

iii) Cervix 

iv) Vagina

i) Oviduct

The ovum is released from ovary into the duct called Oviduct.

Function

Fertilization of ova takes place in first part of the oviduct. Each Oviduct has ciliated cells and non-ciliated cells, and opens into the uterus. The non-ciliated cells produce nutrients and mucus.

Uterus

ii) The zygote is carried into a uterus by ciliated cells and muscular peristalsis, where it attached to the uterus wall forming placenta.

Functions

It's functions is to receive, retain and nourish the fertilized ovum.

iii) Cervix

The uterus opens into a narrow tube called cervix which is normally blocked by plug of mucus.

iv) Vagina

Functions

The copulation occurs in this part. Vagina relaxes during labour so it is also called "birth canal". In female external genitalia is relatively undeveloped and small called "clitoris" that vagina. The urethra opens independently to the exterior near the last end of vagina.

PREGNANCY

Gestation period 

"The period which starts from the implantation up to the birth is called Gestation period or pregnancy".

Gestation in human female is mostly 9 month (280 days). The fertilization occurs in the upper parts of oviduct. The fertilized egg is now called "Zygote". The zygote is then carried toward uterus. On the way toward uterus, the zygote divides by mitosis, due to which the number of cells in embryo increases. When the embryo

reaches to uterus, it attach to the thick walled uterus. "The attachment of embryo to the wall of uterus is called "implantation".

After implantation the embryo form a connection with uterus called placenta. The placenta helps in the exchange of different materials such as nutrients, oxygen, wastes, hormones, etc. The cord like structure that connects the foetus with placenta is called "Umbilical cord ". At the beginning of 3rd month (after eight weeks of pregnancy), most of the organs of the embryo are formed now the embryo is called "Foetus". Heart is first organ to form. The embryo then starts growth that continues up to the birth.

Lactation (or breast feeding)

After birth, the baby is fed by maternal milk. The milk produce initially by the mammary gland contains lymph like fluid called "colostrum" which is rich in antibodies. When the mother stops feeding her baby (mostly up to 2 years) her reproductive cycle begins again, but in some cases the reproductive cycle starts during the breasting feeding.

Female Hormones

In addition to the production of ova, the ovaries also perform as an endocrine gland. When the Follicle cells in ovaries mature, these follicles then secrete different hormones at different instances, these

hormones are:

1) Estrogen

2) Progesterone

1) Estrogen

The ripened (matured) follicles secrete a hormone called "Estrogen".

Functions of Estrogen 

Estrogen is responsible for the primary sex organs and accessory sex organs.

Development of secondary sexual characters such as development of mammary glands, high pitch of voice, hair growth at specific places, broadening of hips, the onset of menstrual cycle etc.

• It helps in release of LH (leutinizing hormone) whose function is to stimulate ovulation.
• It stimulate the thickening of uterine walls by the process of vascularization.
• It helps in conception and maintenance of pregnancy by stimulation of uterine walls to secrete a proteinecious fluid on which the embryo feed at earlier stages.
• It also helps in healing of uterus after menstruation.

If there is under secretion of Estrogen at puberty stage, so the secondary sexual characters will not appear. If the Estrogen is not secreted at adult stage so it will also leads to sterility. After menopause, the secretion of Estrogen stops that leads in the bones become thin and disease called "Osteoporosis', in which bones become weak and thin.

2) Progesterone

Progesterone is secreted by the ruptured follicles called Corpus lutetim.

Functions of progesterone 

1. It inhibits further release of FSH to prevent any more follicle front ripening.
2. Thickness of uterus
3. Suppress ovulation
4. Maintenance of pregnancy in case of fertilization
5. Enlargelnent of mammary gland
6. Prevents uterus from contraction until the onset of labour at birth.