Who or what makes cells for the human body, and how?

New body cells are done naturally by the body via a process known as mitosis. Additionally, scientists can now use stem cells to clone body cells.

Mitosis is the process that makes additional body cells (also known as somatic cells). During mitosis, one parent cell divides into two daughter cells. The number of chromosomes that are characteristic for a species is maintained during mitosis. This is because, prior to the division of the parent cell into two daughter cells, the genetic material of the parent cell is replicated. Mitosis consists of four phases: prophase, metaphase, anaphase, and telophase. Here, the occurrences of the phases of mitosis are briefly described.

Additionally, geneticists can now clone stem cells in order to grow body cells and/or tissues for medical purposes.