Leucocyte diurnal rhythms in normal and pinealectomised juvenile female fowls

Peripheral blood from a group of control and pinealectomised juvenile female fowls was examined to establish which leucocytes manifested a diurnal rhythm and what effect pinealectomy had on these cells. The results showed that significant diurnal rhythms were displayed by the heterophils, lymphocytes and monocytes (P less than 0.001) but not by the eosinophils or basophils. Comparisons made between the control and pinealectomised birds revealed that the heterophil (P less than 0.01) and monocyte (P less than 0.1) counts were higher in the operated birds whereas the lymphocytes were lower (P less than 0.1). The eosinophils and basophils were unaffected. The removal of the pineal gland did not alter the normal diurnal rhythm of the cells.