How to cells undergo differentiation to form the numerous types of cells in the body?

The stem cells that are initially formed in the body undergo differentiation through various chemical signals that drive them to differentiate into appropriate cell types.

Explanation:

The two haploid gelametic cells fuse to form a diploid cell which is got as a zygote. This zygote is a simple cell that undergoes repeated mitotic divisions to form different cellular organelles.

The cells that are differentiated into a particular type thereby they are differentiate into different organ systems according to the chemical signals that are received by the receptors of the cell.

Cell differentiation is how generic embryonic cells become specialized cells. This occurs through a process called gene expression. Gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a cell functions.