Most tissues of the body grow by increasing their cell number, but this growth is highly regulated to maintain a balance between different tissues. In adults most cell division is involved in tissue renewal rather than growth, many types of cells undergoing continuous replacement.
Internal monitors called checkpoints track each step of the cell cycle. In the cell cycle, there are three main checkpoints; one at the end of G1, a second at the transition of G2/M, and a third during the metaphase. Positive molecules of the regulator allow the cell cycle to proceed to the next level.
Mitosis, although continuous process, is conventionally divided into five stages: prophase, prophase, metaphase, anaphase and telophase.
Explanation: The space in the center of the eyeball is filled with a clear jelly-like material called the vitreous humor. This material allows light to pass through to the retina. It also helps the eye keep its round shape.
