This kind of analysis is performed on a scanning electron microscope. A beam of electrons is focussed on a section of the cell. Ions within the cell release X-rays which are characteristic of the particular ion. The movement of water is regulated by moving ions within principal cells of the recta. This is also a factor that has been isolated from corpora cardiaca of locusts.
Physiological models are useful tools.
Nonetheless, we want to underscore the point that these are models. Models are continuously changed to accommodate new information. Let us revisit our general model of DH and ADH actions. As mentioned just above, another anti-diuretic factor has been isolated from the corpora cardiaca, in this case during work on the house cricket. This factor acts on Malpighian tubules and causes a reduction in fluid secretion.