Hyperplasia is the increased number if cells resulting in an increase in the volume of the organ or tissues. It can only occur in cells capable of mitotic division, when the stress is increased. It may occur with hypertrophy (increase in size of cells) resulting increase in organ size.

Type of hyperplasia

It is of two types

Physiological Hyperplasia

It is also of two types

1.  Hormonal Physiological Hyperplasia

2.  Compensatory Physiological Hyperplasia

Hormonal Physiological hyperplasia:

For example

1: Glandular proliferation in females

2: Increase level of ovarian steroids causes hyperplasia in pregnancy

Compensatory Physiological hyperplasia:

Hyperplasia occurs when a portion of tissue is removed or diseased. e.g.

1: Hyperplasia in remaining kidney when other kidney is removed or destroyed as it increase work demand of remaining kidney.

2: When the lever is partially dissected mitotic activity in remaining cells begin an early or 12 hours later, so the string liver to its normal weight. 

Pathological Hyperplasia

It occurs due to excessive stimulation or growth factor stimulation of target cells e.g. 

 Adenomatus Hyperplasia of Endometrium:

 It occurs due to the excessive estrogen stimulation after a normal menstrual period, where the proliferation of uterine epithelial layer occurs that is normally tightly regulated by stimulation through pituitary hormone and ovine estrogen and progesterone is distributed. Endometrial hyperplasia is a common cause of the abdominal bleeding.

In chronic irritation of skin, stimulation of growth factor is evolved in hyperplasia that is

associated with viral infection e.g. viruses causes skin warts and mucosal lesions composed of

masses of hyperplasic epithelium. The growth factor may be produced by the viruses or the

infested cells.

Wound healing:

Hyperplasia is also an important response if tissues cells in wound healing, proliferation,

fibroblast and blood vessels aid in repair.