The effect of laser irradiation on the frog pineal.

The frog pineal is a functional photoreceptor with probable endocrine capabilities. Continuous wave Laser radiation at 514.5 nanometers for 300 sec at 200 mW, as focused on the pineal of the intact frog Rana esculenta to study the functional role of this structure. The investigation was carried out on 80 male specimens - 40 of which were controls - in light and in dark experimental conditions - during the months of March, July and November. The ratio gonad weight/body weight was used to measure the effect of the Laser. The response was consistently similar from control frogs kept in the dark and from Laser-irradiated frogs kept in the light. The same was observed in the opposite situation. Histological examination showed structural modifications of the gonads and skin of Laser-irradiated frogs. These results suggest a functional correlation between the pineal photoreceptor cells and the pineal secretory cells. We hypothesize that the pineal itself might influence gonadal activity through the secretion of an hormone within the third ventricle. The frog's skin did not change colour during the Laser irradiation, we therefore suppose that the structures responsible for the release of the hormone regulating colour changes are not effected by the Laser beam.