Effect of season on histoarchitecture of pineal gland in buffalo (Bubalus bubalis)

Background: The photoperiod and other seasonal variations are the key factors that affect reproduction and production of the animals. The pineal gland secretes melatonin hormone that affects several physiological functions of the body during different seasons. Aims: The present study was conducted to study the histoarchitectural and micrometrical changes in the pineal gland of buffalo (Bubalus bubalis) during different seasons of the year. Methods: Pineal glands of 30 adult female Jaffarabadi buffaloes were collected from the slaughterhouse during the winter, summer, and rainy seasons. Samples were processed by standard histological procedures and stained with various stains for histological and micrometrical observations. Results: The pinealocytes constituted a major cellular portion of pineal parenchyma. The pinealocyte nuclei were lightly stained and more euchromatic during the winter season whereas darkly stained and slightly heterochromatic during summer. The calcium deposits occupied a larger area of pineal parenchyma during the summer as compared to the winter season. The pinealocyte density, the nuclear diameter of pinealocytes, and the number of argyrophilic nucleolar organizer regions (AgNOR) were highest during the winter season as compared to the summer and rainy seasons. Conclusion: The present study shows the influence of season on the histoarchitecture and histometry of the pineal gland of buffalo and indicated higher pineal activity during the winter season in this species.