Consider the following hormones and their role in the workings of the endocrine system: Where the hormone is produced. Hormone(s) secreted. Hormone function. Adrenal glands. Aldosterone. Regulates salt, water balance, and blood pressure.
Sometimes there are tissue-specific mutations that control formation of certain tissues and/or organs. For instance, if mutation affects skin then the skin would be wrinkly/ugly but organism would still develop.
A multicellular organism grows because cell division increases the number of cells in it. As the organism develops and its cells divide, many of the cells become specialized, and most of them continue to divide. Even when growth and development appear to stop, cell division is still occurring.