The Pituitary Gland and Female Reproductive Function
The pituitary gland is a vital organ with many functions. It is a very complicated organ.
We will just touch it's basic functions relating to the regulation of the female reproductive
It is important to understand the principle of negative feedback to be able to understand
the regulatory function
of this gland . The thermostat controlling the geaser that supply hot water to our homes
works on this principle.(negative feedback). Imagine that the thermostat is set to 60 degrees
Celcius. If the tmeperature of the water rises above 60 degrees the power supply is cut
but if the temperature goes below 60 degrees the thermostat reconnects the power.
The pituitary works on the same principle. It produces two hormones that stimulate
the ovaries to produce oestrogen. The two hormones are known as FSH (Folicle Stimulating
Hormone) and LH ( Luteinising Hormone). If the oestrogen levels are low the pituitary gland
produces more FSH and LH . The FSH and LH stimulate the ovary and it producesmore oestrogen.
If the oestrogen levels are high the pituitary gland produces less FSH and LH and hence the
ovary produces less
oestrogen. In a normal healthy female the oestrogen , FSH and LH levels are regulated within
The next diagram illustrates the relationship between the ovaries and pitiutary.
If the oestrogen goes up the FSH and LH go down and vice versa. It is important
to remember that oestrogen is formed in the follicle (see
The Normal Ovary ). FSH is a abbeviation of follicle stimulating hormone and LH of
luteinsing hormone. ( It is necessary for the formation of the yellow body the
CORPUS LUTEUM .
Both FSH and LH are necessary for the normal development of the
follicle and ovulation. It is also important that their levels are regulated by the
negative feedback effect of oestrogen within certain limits.
Following ovulation , the corpus luteum appears . It has a limited live span and LH
plays a posible role in its function. Normal LH levels levels won't be able to expand this
live span beyond ten days.
In the condition known as polycystic ovarian syndrome (PCO)
the LH levels are usually increased.
After the menopause the ovaries ceased to produce oestrogen and the FSH and LH levels become
very high in an effort to stimulate the non responding ovaries(see
The pituitary also produces another important hormone called PROLACTIN. One of prolactin's most
important functions is stimulating the breasts to produce milk. Excessive prolactin production
in non lactating women causes ovarian dysfunction with anovulation ( the ovary stops producing
egg cells) .