Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of .

Autocrine signal, paracrine signal and endocrine signal.

Explanation:

Testosterone is an example of hormone which shows its effect on different locations of the cells.

The autocrine signal can be defined as the siganals which shows its effect on the cell from where it is being produced. This means a cell targets itself.

Then comes the paracrine signals in which signals acts locally on the cells nearby it. The cells close together to the cells producing chemical signals is being affected.

The endocrine signals can be defined as the effect of the hormone on the distant cells. The signals is produced by the cells somewhere else but is carried through the bloodstream to the distant cells.

All of the three effects is being shown by testosterone autocrine, endocrine and paracrine.