Varves form only in fresh or brackish water, because the high levels of salt in normal sea water coagulate the clay into coarse grains. Since the saline waters leave coarse particles all year, it is nearly impossible to distinguish the individual layers in salt waters.
An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, liver, heart, muscle tissue, pancreas, and kidneys. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT). Low levels of AST are normally found in the blood. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage.
Your FSH levels during pregnancy will generally be too low to be measured properly. This might look like the levels are very low. A low count of FSH could indicate the following conditions: A condition known as hypopituitarism, where your pituitary gland does not produce the hormones it is supposed to produce. In some cases, it may produce them in very low quantities. Very poor FSH levels can also indicate a condition known as Turner syndrome.