Development of polycystic ovaries   An ovary is described as polycystic when it contains 12 or more small cystic areas less than 10 mm in diameter. Each month few follicles start growing but arrest before releasing mature eggs because of abnormal hormonal signalling or high male hormones within the ovaries. Recent research work showed excessive follicular development from the primordial stage as a prime abnormality of polycystic ovaries. Accumulation of such small cysts (underdeveloped follicles) leads to the characteristic polycystic appearance which is more common under the age of 35 years than in older women.  These cystic areas form a wide spectrum of growing follicles and atretic cysts. On one side there are many growing follicles and few atretic cysts. On the other side of the spectrum there are many atretic cysts and few growing follicles. Most cases fall in between these two extremes. This could explain the differences in response shown by patients with polycystic ovaries during induction of ovulation. It is not possible to differentiate between these patterns using ultrasonography. Both or one ovary could be polycystic and the cysts could be arranged under the surface or dispersed all over the ovary.

.