Changes in nuclear volume of neurocytes containing lipofuscin pigment in the medulla oblongata of the brain of Rana temporaria l. in the annual cycle.

Sexually mature females and males of Rana temporaria L. having a similar length, were captured directly in their natural habitat in 7 periods of the annual cycle. The volume of the nuclei of the medulla oblongata (MO) cells containing lipofuscin in pigment (LFP) showed significant changes in a year. In both sexes their cell nuclei showed the maximal volume in the phase preceding the mating period (1st decade of March), and relatively high volume in the middle stage of active life on land (2nd decade of July). Directly after the periods of high activity, a considerable decrease in the volume of the nuclei of the examined neurocytes was proved i.e. during the mating period (3rd decade of March) and in the final phase of active life (1st decade of September). Except for the middle stage of active life on land, the changes in the activity of the examinated neurocytes are positively correlated with the changes of the level of intercellular lipofuscins.