Spindles in cells arise in the pre-mitosis or meiosis phase. Animal and lower plant cells emit star rays from the centrosome, and higher plants emit spindle filaments from the poles of the cell. These proteins act as "threads or wires" of the component, extending from the poles to the center of the cell, resembling a spindle and known as spindles. However, many young people have never seen a spindle, and it is not easy to associate a spindle shape.
What exactly does a spindle look like? We have to start with the spinning thread. Silkworms spit out silk when cocooning, and cotton fruits spit out flocculent silk when ripe. Wool and hemp can also be artificially stripped to obtain a large number of natural spinning raw materials. If you use these fibers to cover people directly, they will fall apart in a short time. Spinning thread is simply the process of rubbing fine fibers together to strengthen toughness. People first twist the elongated fibers into a small "guide" thin line by hand, and then bind the thin line to the bone rod or wooden stick groove as a rotating tool, and continuously rotate the rod in the same direction to make the natural fibers wind into thin lines. Smart people also add a large mass wheel to the middle or bottom of the stick. In this way, after the finger turns the spindle, the number of spindle rotations can be increased by relying on the inertia of the rotor. This is why some spindles have a large disc. Later, people used the large wheels of hand or foot brakes to drive the small discs on the spindle to rotate with the help of "belts", and this labor-saving textile tool was the spinning wheel.
With the accumulation of thin lines, the whole of the "thick and thin in the middle" line is gradually formed, resembling an olive, which is the spindle shape. So don't understand the "spindle shape" in terms of the spindle stick in the photo, the spindle stick with a disc, or even the outline of the spinning wheel. In nature, birds flying in the sky and fish swimming in the water are similar to spindles, which can greatly reduce their resistance when they move.