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 progesterone and estrogen from the ovarian cycle also control the menstrual cycle: 1  If implantation doesnât occur and the levels of estrogen and progesterone fall, the endometrium sloughs off, and menstrual bleeding begins. 2  As the levels of estrogen begin to rise, the endometrium thickens.