The sex hormones of the male follow a much simpler pattern than do those of the female, although the same principle of interaction exists between the pituitary gland and the gonads. The latter organs, the testes , secrete steriods called androgens , which are responsible for the maintenance of male characteristics and behaviour. FSH from the pituitary gland stimulates the growth of the seminiferous tubules that constitute much of the structure of the testes and promotes within them the cell divisions that result in the production of mature sperm . LH from the pituitary gland promotes the development within the testes of endocrine tissue, which is composed of groups of cells (interstitial tissue) between the seminiferous tubules. The interstitial tissue of certain bony fishes, however, is represented by cells, called lobule boundary cells, situated within the tubule tissue.
Alendronate (Fosamax), risedronate (Actonel), zoledronic acid (Reclast), and raloxifene (Evista) have an indication from the Federal Drug Administration (FDA) for the prevention of osteoporosis (such as for those with osteopenia), as well as for the treatment of osteoporosis. For raloxifene (Evista) and risedronate (Actonel), the doses used for osteopenia are the same as those used for osteoporosis. Zoledronic acid (Reclast) is an intravenous medication given yearly for the treatment of osteoporosis but every other year for the prevention of osteoporosis. Alendronate (Fosamax) is given as 10 mg daily or 70 mg weekly for osteoporosis, and the dose is halved for the prevention of osteoporosis (5 mg daily or 35 mg weekly).