Figure 1.

Environmental conditions can influence decent generations by distinct modes. The first column represents the exposure of an adult rodent to a stressful or aversive environment not only affecting the neural system of the exposed generation but also the germ cell through direct exposure. The germ cells give rise to the F1 generation representing an intergenerational transmission. The germ cells of the F1 generation are not exposed to the stressor and generate the subsequent F2 generation that represents a transgenerational transmission, which is not exposed to the stressor by means of a direct exposure or exposure of the germ cells. The second column represents the in utero exposure of a developing F1 generation to an environmental factor. This generation and the F2 generation, by means of the developing germ cells, are directly exposed, thus, representing an intergenerational transmission. The F3 generation represents the first generation that was not exposed to the stressor representing a transgenerational transmission. The third column represents the exposure of a F1 generation during postnatal development. Similar to the second example, this F1 as well as the F2 generation is directly exposed and therefore represent intergenerational transmission, with the following F3 generation representing a transgenerational transmission.