Using a customer supplied envelope, an individual can mail a Priority Mail Express letter envelope weighing one ounce up to sixteen ounces for $31.20 plus the extra fee of $12.50 to add Sunday/Holiday Delivery.
muscle cell-an elongated contractile cell that forms the muscles of the body. muscle fiber, muscle fibre. fibre, fiber-any of several elongated, threadlike cells (especially a muscle fiber or a nerve fiber).
Human muscles contain hundreds of thousands of muscle cells and each muscle cell performs a function specific to the type of muscle of which it is a part. Individual muscle cells, or muscle fibers, are composed of myofibrils-cylindrical structures which contain both thick and thin filaments.