title: Seasonal changes in glycogen level and size of pinealocytes of the white-footed mouse, Peromyscus leucopus: a semiquantitative histochemical study.
abstract: Glycogen level in and size of pinealocytes of the feral, white-footed mouse Peromyscus leucopus, were studied by a semiquantitative histochemical method to determine whether seasonal changes exist in them under natural conditions, what temporal pattern they exhibit, and whether 24-hour changes in these parameters exist in different seasons, as shown in the laboratory dd-mice. Marked seasonal changes were seen in both glycogen levels and nuclear densities (ANOVA p less than 0.005). The size of pinealocytes at 09:00 to 10:00 showed one peak (and nadir) seasonal change, with the smallest size in winter (December and February) and a larger size in warmer seasons, with the maximum value in July. Glycogen level in pinealocytes at 09:00 to 10:00 showed bimodal seasonal changes, with lower levels in fall and spring and higher levels in winter and summer. In fall, a circadian trend in glycogen level in pinealocytes was seen, with a higher level at the end of the light period. In winter, the glycogen levels were very high at 09:00, 13:00, 17:00, and 21:00 examined and showed dampening of time-of-day differences. On the other hand, the size of pinealocytes followed a time-of-day change (P less than 0.005), being largest at 13:00 and smallest at 21:00. Thus, marked changes in quantitative structure and chemical activities, suggesting changes in functional activity, in pinealocytes were noted especially in severe, cold winter.
mesh_terms: D000064:Acclimatization; D000818:Animals; D001835:Body Weight; D005260:Female; D006003:Glycogen / Q000378:metabolism*; D008297:Male; D010542:Peromyscus / Q000378:metabolism*; D010870:Pineal Gland / Q000166:cytology / Q000378:metabolism*; D012621:Seasons; D012737:Sex Factors
chemical_list: D006003:Glycogen