At puberty, the<unk>  begins to secrete increasing levels of hormones. Secondary sex characteristics begin to develop in response to the hormones. The<unk>  changes structure and function beginning at puberty. Since the<unk> es are able to regulate hormones, they also play an important role in pregnancy and fertility. When egg cells (oocytes) are released from the Fallopian tube, a variety of feedback mechanisms stimulate the endocrine system which cause hormone levels to change. These feedback mechanisms are controlled by the hypothalamus and pituitary gland. Messages from the hypothalamus are sent to the pituitary gland. In turn, the pituitary gland releases hormones to the<unk> es. From this signaling, the<unk> es release their own hormones. Gamete production The process of<unk> ulation and gamete production, oogenesis, in a human<unk> . The<unk> es are the site of production and periodical release of egg cells, the female gametes. In the<unk> es, the developing egg cells (or oocytes) mature in the fluid-filled follicles. Typically, only one oocyte develops at a time, but others can also mature simultaneously. Follicles are composed of different types and number of cells according to the stage of their maturation, and their size is indicative of the stage of oocyte development. When the oocyte finishes its maturation in the<unk> , a surge of luteinizing hormone secreted by the pituitary gland stimulates the release of the oocyte through the rupture of the follicle, a process called<unk> ulation. The follicle remains functional and reorganizes into a corpus luteum, which secretes progesterone in order to prepare the uterus for an eventual implantation of the embryo. Hormone secretion At maturity,<unk> es secrete estrogen, androgen, inhibin, and progestogen. In women before menopause, 50% of testosterone is produced by the<unk> es and released directly into the blood stream. The other 50% of testosterone in the blood stream is made from conversion of the adrenal pre-androgens ( DHEA and androstenedione) to testosterone in other parts of the body. Estrogen is responsible for the appearance of secondary sex characteristics for females at puberty and for the maturation and maintenance of the reproductive organs in their mature functional state. Progesterone prepares the uterus for pregnancy, and the mammary glands for lactation. Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium.<unk> an aging As women age, they experience a decline in reproductive performance leading to menopause. This decline is tied to a decline in the number of<unk> an follicles. Although about 1 million oocytes are present at birth in the human<unk> , only about 500 (about 0.05%) of these<unk> ulate, and the rest are wasted. The decline in<unk> an reserve appears to occur at a constantly increasing rate with age, and leads to nearly complete exhaustion of the reserve by about age 52. As<unk> an reserve and fertility decline with age, there is also a parallel increase in pregnancy failure and meiotic errors resulting in chromosomally abnormal conceptions. The<unk> an reserve and fertility perform optimally around 20–30 years of age. Around 45 years of age, the menstrual cycle begins to change and the follicle pool decreases significantly. The events that lead to<unk> an aging remain unclear. The variability of aging could include environmental factors, lifestyle habits or genetic factors. Women with an inherited mutation in the DNA repair gene BRCA1 undergo menopause prematurely, suggesting that naturally occurring DNA damages in oocytes are repaired less efficiently in these women, and this inefficiency leads to early reproductive failure. The BRCA1 protein plays a key role in a type of DNA repair termed homologous recombinational repair that is the only known cellular process that can accurately repair DNA double-strand breaks. Titus et al. showed that DNA double-strand breaks accumulate with age in humans and mice in primordial follicles. Primordial follicles contain oocytes that are at an intermediate (prophase I) stage of meiosis. Meiosis is the general process in eukaryotic organisms by which germ cells are formed, and it is likely an adaptation for removing DNA damages, especially double-strand breaks, from germ line DNA (see Meiosis and Origin and function of meiosis). Homologous recombinational repair is especially promoted during meiosis. Titus et al. also found that expression of 4 key genes necessary for homologous recombinational repair of DNA double-strand breaks (BRCA1, MRE11, RAD51 and ATM) decline with age in the oocytes of humans and mice. They hypothesized that DNA double-strand break repair is vital for the maintenance of oocyte reserve and that a decline in efficiency of repair with age plays a key role in<unk> an aging. A study identified 290 genetic determinants of<unk> an ageing, also found that DNA damage response processes are implicated and suggests that possible effects of extending fertility in women would improve bone health, reduce risk of type 2 diabetes and increase the risk of hormone-sensitive cancers. A variety of testing methods can be used in order to determine fertility based on maternal age. Many of these tests measure levels of hormones FSH, and GnrH. Methods such as measuring AMH (anti-mullerian) hormone levels, and AFC (antral follicule count) can predict<unk> an aging. AMH levels serve as an indicator of<unk> an aging since the quality of<unk> an follicles can be determined.
Ovary
Callus
Pelvis
Breast
Lutetium 
Serous gland
Adrenal gland
Testicle