Here are some quick tips on how to distinguish classic crystal from plain glass. 1  Hold up a glass to the light. 2  If the glass acts as a prism and you see a rainbow you are holding crystal. 3  If not, it is just plain glass. 4  When struck, crystal produces a musical ring. 5  Glass does not.
Hormonal control of menstrual cycle. The ovarian hormones circulate in the blood and are excreted in modified forms in the urine. Estimation of the urinary output by chemical methods gives an indication of the blood levels and of the total production of these substances.
The ovaries produce estrogen and progesterone in women. Both play an important role in the menstrual cycle: estrogen stops FSH production and stimulates LH release by the pituitary gland. Progesterone maintains the uterusâ lining. Men also produce estrogen, though at lower levels, and this is done through changing testosterone into estrogen with an enzyme.