Yasunobu Eguchi

Histological Changes in the Placenta Induced by Maternal Alcohol Consumption in the Rat

To investigate the placental enlargement which accompanies maternal alcohol consumption during pregnancy, Sprague-Dawley rats were given 20% ethanol for 4 weeks prior to mating and 30% ethanol throughout gestation. Pair-fed controls received an isocaloric amount of corn starch and chow, with water ad libitum, and ad libitum controls received rat chow and water. On days 17, 18, 19 and 20 of gestation, placentas were removed for histological observation. On days 18-20, the placentas of alcohol-fed rats weighted significantly more than did those of controls, although there was no difference in weight on day 17. Giant cells in the basal zone were significantly increased in number and size in alcohol-fed rats compared to controls. Trophoblastic cells in the basal zone were significantly larger in the alcohol group than in the control groups except on day 17. The maternal blood channels in the labyrinth were wider and more filled with blood corpuscles in the alcohol group than in either control group. It is concluded that the increased weight of the placenta may be largely due to stagnated maternal blood cells in the labyrinthine blood channels and also to the increased number and size of giant cells and the enlarged trophoblastic cells in the basal zone.

Onset of the Constrictive Effect of Indomethacin on the Ductus arteriosus in Fetal Rats

The time of onset of the constrictive effect of indomethacin on the ductus arteriosus (DA) in fetal rats was assessed by measurement of the caliber of the DA after maternal treatment with indomethacin on days 19-21 of gestation. The day following overnight mating was regarded as day 0 of gestation. Observation was performed by direct exposure of the DA by hand shaving of intact frozen fetuses. On days 20 and 21, the DA was significantly constricted 3 h after maternal treatment with 1 mg/kg of indomethacin. When the DA was examined at 19 1/2 and 19 2/3 days of gestation (3 h after indomethacin exposure), it was significantly constricted at 19 2/3 days but not at 19 1/2 days. Higher doses of indomethacin (10 and 100 mg/kg) induced a significant constriction of the DA at day 19 1/2, but not at the beginning of the same day (1.00 a.m.). These results suggest that the onset of the susceptibility of the DA to the constrictive effect of indomethacin occurs in the first half of day 19 of gestation.

Studies on the Development of the Fetal and Neonatal Bovine Stomach

37 Holstein fetuses and 5 newborn holstein calves were used in a study of the development and neonatal anatomy of the bovine stomach. Care was taken to prevent alterations in pulmonary volume and modification of topographic relationships between stomach compartments. Polymerized synthetic polyester resin was used to form anatomic casts of stomach compartments. This technique provided the basis for a description of relative sizes and relationships of stomach compartments and the nature of the mucosal surfaces.

The sensitivity of the fetal rat adrenal gland to adrenocorticotropic hormone in vivo and in vitro.

Rat fetuses were treated with 1 IU ACTH on day 16 or 17 of gestation and autopsied on the next day. Other fetuses of the same litter were treated with saline alone. The adrenal glands of ACTH-treated fetuses were significantly heavier than those of saline-treated fetuses and of intact controls in every experimental period. These changes in the weight of fetal adrenal glands reflect histologically on changes in the size of adrenocortical cells which were enlarged in response to injected ACTH. Adrenal glands from rat fetuses of different ages were explanted to organ cultures for 2 days, in medium with or without ACTH added. The 13-day adrenal glands were not able to respond to ACTH, but the response appeared abruptly in the 14-day adrenal glands, judging from the increased cell size in histological sections. The overall results suggest that the fetal adrenal gland begins to respond to ACTH from day 14 of gestation.

Immunocytochemical changes in the fetal pancreatic islet following fetal administration of streptozotocin in the rat.

Streptozotocin (STZ) is selectively toxic to the B cells in the pancreatic islets. It is well known that in the adult rat, STZ causes the death of B cells, and it eventually induces diabetes mellitus. The present study was conducted to detect what morphological changes could be induced in the fetal B cells following a direct injection of STZ into the fetus in utero during late pregnancy in the rat.

Effect of Acute Maternal Alcohol Consumption on the Fetal Ductus arteriosus in the Rat

This study was conducted to determine whether acute alcohol consumption in near-term pregnant rats results in constriction of the fetal ductus arteriosus (DA). Twenty milliliters per kilogram of 30% (v/v) alcohol was administered via a stomach tube 0.5, 2, 4, 6 and 12 h prior to cesarean section and fetal sacrifice, at 1.00 p.m. on the 20th gestational day (day 20.5), in experimental groups A1-A5, respectively. Controls were given water alone. The calibers of the DA and pulmonary artery (PA) were measured using the whole-body freezing method with direct exposure of the DA and PA by shaving the frozen chests of the fetuses. The DA was significantly constricted 30 min after alcohol treatment. The constriction was also observed in groups A2-A4, but not in group A5. The PA was also less markedly but significantly constricted 30 min after alcohol administration, but groups A2-A5 showed normal PA caliber. It is concluded that alcohol has a constrictive effect on the DA when administered close to the end of gestation in the rat.

Maternal adrenocortical hormones maintain the early development of pancreatic B cells in the fetal rat

To investigate the effect of maternal adrenocortical hormones on the development of fetal pancreatic islet cells, pregnant rats were adrenalectomised on d 6 of gestation. On d 12–16 the growth patterns of fetal insulin‐producing B cells, glucagon‐producing A cells, and somatostatin‐producing D cells were observed histometrically. Maternal adrenalectomy resulted in growth retardation of fetal B cells on d 12–15. Maternal corticosterone therapy prevented this retardation. Maternal adrenalectomy, however, did not affect the developmental patterns of A and D cells. By Western blotting and immunohistochemistry, glucocorticoid receptors were demonstrated to be present in the islet cells from d 12 to d 15. These results suggest that maternal adrenocortical hormones, glucocorticoids in particular, maintain the early development of fetal pancreatic B cells through their specific intracellular glucocorticoid receptor.

Effect of follicle-stimulating hormone on sertoli cell division in cultures of fetal rat testes.

The present study was performed to determine when follicle-stimulating hormone (FSH) begins to promote Sertoli cell division in fetal rats, and to determine whether the effect of FSH is mediated by cAMP-dependent protein kinase (PKA). When testes from 15- to 17-day fetuses were cultured with or without FSH for 48 h, FSH did not promote Sertoli cell division in 15-day testes, but did in 16- and 17-day testes. Anti-rat FSH was injected into 16-day fetuses in utero. Twenty-four hours later, the testes of the injected fetuses and those of their intact littermates were cultured with or without FSH for 48 h. Without FSH, the Sertoli cell division index was significantly lower in anti-FSH-treated fetuses than in intact fetuses. With FSH, however, the index increased. When PKA inhibitor was added to cultures of 16-day testes with FSH, the promotion of Sertoli cell division by FSH was inhibited. We conclude that between 16 and 17 days of gestation, fetal pituitary FSH stimulates the division of Sertoli cells by activating the PKA activity.

Developmental Changes in Fetal Adrenal Hypertrophy following Maternal Bilateral and Fetal Unilateral Adrenalectomy at Different Stages of Gestation in the Rat

Maternal adrenalectomy on days 14 and 15 of gestation did not alter the fetal adrenal weight 2 days later. The same operation on day 16 caused a significant increase in the adrenal weight with a hypertrophy of the cortical cells. Nevertheless, the operation on days 17 and 18 induced no change in the fetal adrenals. Subsequently on days 19 and 20, the operation resulted in a significant hypertrophy of the fetal adrenals. Fetal unilateral adrenalectomy on day 18 caused, 2 days later, significant hypertrophy of the contralateral adrenal, in contrast with no significant change after maternal adrenalectomy. This is perhaps due to the difference in the amount of fetal plasma corticoids, as evidenced by the previous reports of high concentrations of fetal plasma corticosterone on days 19 and 20. The overall results suggest that the fetal pituitary-adrenal feedback mechanism begins to appear between days 16 and 18 of gestation.

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

Perinatal changes of the gastric parietal cells were studied under normal and various experimental conditions. Histologic examination revealed that the parietal cells appeared markedly increased in number from late fetal to early neonatal days. When premature newborn rats were delivered by cesarean section and were nursed by foster mothers for 1 or 2 days, the degree of increase of these cells reached nearly that in the normal neonates. On the other hand, in fetuses retained in utero 1 day beyond the normal gestation, these cells appeared not increased in number. When these postmature fetuses were delivered, the parietal cells turned to increase in number in a degree similar to that in the normal neonates. Milk given to the premature newborn rats caused 6 h later a marked increase in the number of the parietal cells. Milk given to fetuses in utero also caused an increase of these cells. The results suggest that the development of the parietal cells in perinatal rats is accelerated by the intake of milk and that the fetal parietal cells are ready to respond to milk given at least 1 day before birth.