Instead, it stated that the decision to get routine screening mammograms before age 50 should be an individual one and take patient context into account, including the patient's values regarding specific benefits and harms..
The seed coat helps protect the embryo from mechanical injury, predators and drying out. Depending on its development, the seed coat is either bitegmic or unitegmic. Bitegmic seeds form a testa from the outer integument and a tegmen from the inner integument while unitegmic seeds have only one integument.
Some seeds have a tough seed coat that does not allow moisture to penetrate for many months, sometimes years. This hinders germination since the seeds have to have warmth and moisture to germinate. For something small, like morninglory seeds, you can rub them between two pieces of sandpaper.