Diurnal rhythm of hypophyseal cells in mice. Part III. Pars nervosa.

Karyometric analysis revealed a distinct diurnal rhythmicity of the nuclear volume of pars nervosa pituicytes in mice maintained on a 12 h light:dark schedule. Maximum nuclear volumes of pituicytes in both males and females were observed at 1800 o'clock while the minimum ones at 1200 o'clock. In addition, a distinct rhythm was observed in the amount of lipid vacuoles in the pituicytes of both sexes; they showed two peaks, a larger one at 1800 and a smaller one at 600 o'clock, as well as two minima at 1200 and 2400 o'clock.