Ultrastructure of the ram pinealocytes during breeding season in natural short and in artificial long photoperiods.

The study was performed from 20th September to 20th October on eight Polish Longwool rams, variety Pomorska (Pomeranian), aged 33 months, which were divided into two equal groups. The animals of control group were kept in natural photoperiod. The experimental group was maintained during 30 days in controlled lighting conditions (16L: 8D). On the thirtieth day of the experiment the animals were slaughtered between 1000h and 1200h. The pineal glands were prepared for EM. Point count analysis was employed to estimate the relative volumes of pinealocyte organelles. The increase of relative volumes of mitochondria and lipid droplets in comparison to the control was observed in the experimental group. There were also some qualitative changes in organization of granular endoplasmic reticulum and microtubules.