What are sex hormones ?

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There are five important hormones whose blood concentrations vary with the menstrual cycle:  estrogen,  progesterone, luteinizing hormone (LH), follicular-stimulating hormone (FSH) and testosterone.   Estrogen is a steroid secreted primarily by the ovaries.  Its main role is to favor development of the female reproductive system and secondary sexual characteristics.  However, it also helps regulate electrolytes (charged ions) in the body liquids, and contributes to protein synthesis.  Men also synthesize (develop) estrogen,  though in lesser concentrations than women.  About half of the man’s estrogen secretion comes from the adrenal gland,  and the other half from the testes,  while an additional part of the total estrogen is derived from testosterone.   Progesterone is also a steroid secreted by the ovaries.  Its main function is to prepare the endometrium (a layer of the uterus) for implantation of the fertilized ovum.   It also favors secretion of milk.  Luteinizing hormone is secreted by an important endocrine gland located at the base of the brain called the hypophysis (also known as the pituitary gland). It liberates an ovum from the ovary thus making it eligible for fertilization and regulates production of ovarian hormones.  Follicular-stimulating hormone is also secreted by the hypophysis.  It contributes to early development of the ova,  and regulates production of ovarian hormones.  Testosterone is a male steroid hormone which is also secreted by the female body (50% by the adrenal cortex and 50% by the gonads). In men it is mostly secreted by the testes and its blood concentration is about twenty times higher than in women. Its function includes control of the development of the male sexual organs and secondary sexual characteristics,  and it favors protein synthesis.   Most of these hormones are believed to influence non-reproductive behavior and even cognition in particular.   For example, studies of the drop in estrogen associated with menopause have shown significant cognitive effects.  A drop in estrogen produces a male-typical cognitive profile.  Interestingly,  luteinizing hormone and even LH-releasing hormone (a precursor of LH)  seem to have similar cognitive effects as estrogen.  One group of investigators injected LH-releasing hormone and LH intravenously to normal men,  and observed a significant increase in verbal abilities and a drop in mental rotation spatial performance.   Several studies have found that testosterone levels in men correlate positively with (may be partly responsible for)  visuospatial abilities.