Question

what is a polycystic ovary?and wat changes do they cause in the reproductive system of the females?

Answer 1

PCOS - is a condition associated with subfertility, acne, hirsutism and obesity. it is defined by2/3 of the following (if i remember correctly, but that is the general idea): a characteristic poly cystic ultrasonogram, high levels of androgens and lack of (or low occurences) of ovulation.
as for the symptoms of acne and hirsutism - taking the pill - prescribed by an OBGYN for that purpose helps a lot. as for subfertility - there are ways to aid pregnancies. all in all it is fairly common - 5-10% of women.

Answer 2

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001408/

Answer 3

http://en.wikipedia.org/wiki/Polycystic_ovary_syndrome

Answer 4

Polycystic Ovarian Syndrome is the most common cause of infertility in women. It's primarily characterized by a dysfunction of the ovaries and excessive production of androgens.

As for your second question, PCOS affects the female reproductive system in a few ways. Two-thirds of patients with PCOS will have anovulatory symptoms such as not getting your menstrual period more than 4 times a year. Or dystfunctional uterine bleeding - bleeding lasting more than 7 days or bleeding that occurs of intervals less than 21 days. These conditions provide an environment where it is harder to conceive = infertility. Also, chronic anovulation increases your risk for endometrial cancer.