Pineal gland structure and respiration as affected by age and hypocaloric diet

Development of the Mammalian Pineal Gland

“…By the 90th postnatal day, virtually all nuclei have become creased or folded in this man ner. A tendency for nuclear contours to be come irregular with age has also been ob served within human fetal pineal cells [27], After birth, the cytoplasmic volume of in dividual pineal cells increases dramatically |69], Since the total number of pineal cells re mains constant or may even decrease after this time [8,68], the density of cells within the pineal changes considerably during postnatal life. Between birth and adulthood, pineal cell density decreases by 20% [68] while cell nu cleus density decreases by 70% [31].…”

“…A tendency for nuclear contours to be come irregular with age has also been ob served within human fetal pineal cells [27], After birth, the cytoplasmic volume of in dividual pineal cells increases dramatically |69], Since the total number of pineal cells re mains constant or may even decrease after this time [8,68], the density of cells within the pineal changes considerably during postnatal life. Between birth and adulthood, pineal cell density decreases by 20% [68] while cell nu cleus density decreases by 70% [31]. Postna tal hypertrophy of the cytoplasm results in the decreased intracellular density of the nu cleus, nucleoplasm [8,10] and mitochondria [43], even though the total mass of each of these organelles within the pineal increases after birth.…”

“…This cellular hypertrophy results in a 20% increase in wet pineal weight during the first 12 h following birth while no such weight change occurs in 10-day-old rats [26|. Cellu lar hypertrophy of postmitotic pinealocytes occurs primarily during the 12 weeks after birth [57], during which time dry pineal weight [68], wet pineal weight [ 10,21,31.53]. and pineal volume [31.57] attain adult values in the rat and mouse.…”

“…Cell proliferation has been estimated in the pineal with the arrest of mi tosis by colchicine [59], with the incorpora tion of H3-thymidine into the DNA of divid ing cells [66], and by light microscopy of mi totic chromosomes [17], Each of these tech niques reveals the percentage of pineal cells that arc in mitotic division at various ontoge netic times. Numerous mitotic stages are first seen within pineal 'parenchyma' (endocrine secretory cells) on the 18th day of gestation [17], Parenchymal cell division occurs at the greatest rate within a few days after birth [68] and steadily decreases thereafter [62]. 25-50% of all pineal parenchymal cells have divided for the last time by the 2nd day of life [20] and cell division is about 95% complete by the end of the 2nd postnatal week [68].…”

“…Numerous mitotic stages are first seen within pineal 'parenchyma' (endocrine secretory cells) on the 18th day of gestation [17], Parenchymal cell division occurs at the greatest rate within a few days after birth [68] and steadily decreases thereafter [62]. 25-50% of all pineal parenchymal cells have divided for the last time by the 2nd day of life [20] and cell division is about 95% complete by the end of the 2nd postnatal week [68]. Ne vertheless.…”