How do Cells form different types of tissues?

easy, stem cells.
Differentiation is the process by which a cell changes to become specialized for it's chosen 'job' e.g. white blood cells are used to fight infections but cannot carry oxygen like red blood cells.
Basically stem cells, found in aborted fetuses and embryos as well as in bone marrow, are cells which are undifferentiated - meaning they can develop into different types of cells depending on what 'instructions' they are given.
They can form different types of cells during stem cell research where stem cells are extracted from say, embryos and grown. To get one specific type of cell, scientists attempt to control the differentiation of the stem cells by growing them in different environments. So far it's still in the experimental stages - lots more research is needed.

The initial cells are called stem cells which multiply and form different types of cells and tissues and eventually the specific organism. This process is carried out by the genetic code embedded in the chromosome of the cells of which acts as a set of rules and regulations which the stem cells follow.

actually after cleavage, the blastomeres formed get arranged into inner cell mass and trophoblast layer. then the inner cell mass, according to their cytoplasmic content divide into ectoderm,mesoderm and endoderm. and then these form different tissues.....hope this will help u..

Thx all!