Perinatal changes in size of pancreatic acini in the rat with special reference to effects of fetal decapitation and fetal or neonatal oral administration of water or milk

Abstract

Normally, the size of pancreatic acini is remarkably decreased after birth in the rat.Administration of water or milk on day 21 of gestation resulted in decreased acinar size a day later in intact fetuses and in fetuses decapitated immediately after administration of water or milk. The same treatments of premature newborn rats obtained by Caesarean section on day 22 of gestation induced similar effects a day later. On the other hand, in starved Caesarean newborn rats, there were no histologic changes in acini. In spontaneous newborn rats which were allowed to suckle maternal milk and then starved for one day, there was an increase in acinar size as compared with that of 2-day-old normal rats.These results suggest that the fetal pancreatic acini at least near term (on day 21 of gestation) can respond to some signals conveyed from digestive tracts which have responded to exogenous stimuli, that the brain during fetal days does not play any role in digestive tract-pancreatic acini interrelations in secretion of zymogen granules and that the neonatal decrease in acinar size is caused by the intake of maternal milk.

Light- and Electron-Microscopic Studies on the Gastric Parietal Cells in Perinatal Rats

“…These pups were divided into two groups. Those of the one group were orally given approximately 0.2-0.3 ml cow's milk soon after cesarean delivery by the method reported from our laboratory (12), and those of the other group were not nursed. All pups were kept at 37 °C and autopsied 6 h later.…”

“…In the fifth series, fetuses on day 21 of gestation were orally given in utero approximately 0.2-0.3 ml cow's milk by the method reported from our labora tory (12). Autopsy was made 1 day later (on day 22 of gestation).…”

Morphometrical changes in the apical surface of the colonic absorptive cells in perinatal rats with special reference to the effect of fetal oral administration of milk in utero

“…Fetuses on days 20,21 and 22 of gestation and neonates on days 1, 2 and 3 of neonatal life were obtained. On day 20 of gestation, some of the fetuses were orally given O' 3 mg of powdered milk dissolved in 0-1 ml of distilled water, in utero, according to the method described by Morikawa et al (1974). Pregnant rats were kept at a room temperature of 23-25°C and were exposed to artificial fluorescent light for 14 h per day.…”

Perinatal Development of Brunner’s Glands in the Rat: Morphometrical Study

“…In fetal rats, gastric parietal cells se crete acid at least 1 or 2 days before birth [8,9], In perinatal rats, in addition, the number of parietal cells markedly increases from late fetal to early neonatal days, although the de gree of increase in these cells is accelerated to reach nearly that on neonatal days when some food material, such as milk, is introduced into the fetal stomach 2 days before birth (day 21 of gestation) and killed at the end of gestation (day 22 of gestation) [10]. Incidentally, the population of colonic goblet cells increases from fetal day 20 to neonatal day 2 with a striking increase between fetal day 22 and neonatal day 1 [11], The size of pancreatic acini also remarkably decreases after birth [12]. These findings suggest that the digestive tract will show noticeable changes in mor phology and physiology following birth.…”