[Ultrastructural organization of the mammalian pineal body during postnatal ontogenesis].

Ultrastructural organization of the components composing the mammal pineal gland is analyzed on the basis of literature data and personal observations. Variations in the form, size and ultrastructural organization of the cellular elements in the pineal gland--pinealocytes, interstitial and glial cells--are discussed. The problem of dark and light pinealocytes is considered as a part of a general biological problem on the presence of dark and light cells as a reflection of the law on "intermittent activity of functional structures". An attention is paid to the organization of the microcirculatory bed and pericapillary space to the peculiarities of the secretory process in the organ. Dynamic changes in the cytologic organization of pinealocytes and other components of the organ in the postnatal ontogenesis are presented in detales.