1 Each muscle fibre ( muscle cell ) is covered by a plasma membrane sheath which is called the sarcolemma. 2  Tunnel-like extensions from the sarcolemma pass through the muscle fibre from one side of it to the other in transverse sections through the diameter of the fibre.keletal muscles consist of 100,000s of muscle cells (also known as muscle fibers) that perform the functions of the specific muscle of which they are a part.
Another leafy vegetable high in beta carotene in the form of vitamin A, kale has 478 milligrams of the nutrient and 20 calories per half cup serving. Kale recipes to try: â¢ Kale Chips. â¢ Roast Cod with Bacon, Potatoes, and Kale. â¢ Kale Salad with Glazed Onions and Cheddar.
Green leaf lettuce contains vitamin A in the form of three carotenoids: beta-carotene, lutein and zeaxanthin.Beta-carotene is converted into the type of vitamin A thatâs needed for normal vision and to support the immune system.reen leaf lettuce contains vitamin A in the form of three carotenoids: beta-carotene, lutein and zeaxanthin.