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.
1 In women, LH helps regulate the menstrual cycle and egg production (ovulation). 2  The level of LH in a woman's body varies with the phase of the menstrual cycle. 3  It increases rapidly just before ovulation occurs, about midway through the cycle (day 14 of a 28-day cycle).