ABSTRACT Neural crest cells appear on top of the neural folds at closure of the neural tube. These cells are capable of migrating and differentiating into multiple tissues. In 1983, Kirby et al., using chimera methodology, reported that cranial neural crest cells participated in aorticopulmonary and truncal septation. Since that time, many experimental studies have been done in this field. In this paper, we report new experimental findings and review four areas of study on neural crest cells, i.e. their general characteristics, participation of neural crest cells in formation of the normal heart, cardiovascular anomalies due to ablation of the neural crest cells, and the relationship between neural crest cells and congenital malformation syndromes, especially the DiGeorge sequence.
SUMMARY Yellow KK mice with non-insulin dependent diabetes were mated at 7 (group A) or 13 (group B) weeks of age. On day 13, 16, or 18 of pregnancy, the plasma glucose concentration in dams was determined, and the embryos/fetuses and placentae were weighed and examined. The rate of early embryonic death was high and invariable on all three days. The rate of late death increased with advancing pregnancy in both groups and the incidence in group B was higher than in group A on each of the three days. On day 13 of pregnancy, maternal plasma glucose concentration in group B was significantly higher than in group A (465 mg/dl vs 230 mg/dl). Embryonic and placental weights in group B were less than those in group A (84 vs 113 mg and 59 vs 68 mg). In group B, there was an inverse correlation between the maternal plasma glucose concentration and the embryonic weight. A similar inverse correlation existed between the maternal plasma glucose concentration and the placental weight. On days 16 and 18 of pregnancy, fetal weights in group B were less than those in group A, but placental weights did not differ significantly be- tween the two groups. From these results, it appears that in the yellow KK mouse fetal growth retardation has already begun in the organogenesis period and is closely related to maternal hyperglycemia.
ABSTRACT Neural tube defects (NTDs) were demonstrated to occur at a high rate (29.4%) in non-obese diabetic (NOD) mouse embryos on day 13 of gestation. Macroscopically, three different forms of NTDs were observed: the combined form of exencephaly and myeloschisis, the pure form of exencephaly, and that of myeloschisis. The neural walls of the open tube were everted bilaterally. It was microscopically demonstrated that NTDs were composed of not only the everted neural walls but also voluminous mesenchymal tissue adjacent to the everted neural walls. The everted neural wall had three-layered structure made up of outer, intermediate, and inner zones. The morpho- logical findings of the intermediate and inner zones were similar to those of mantle and marginal layers in the normally closed neural tube. However, the outer zone, which cor- responded to the ependymal layer in the normal neural tube, had characteristic findings. Namely, the cells were small, round and uniform in shape. Almost no mitotic figures were observed in this zone, and electron microscopic investigation revealed few cytoplasmic organelles. Of 9 NOD mouse embryos with NTDs, 2 exhibited duplicated notochords. In one of these two embryos, an aberrant tuba1 structure was formed of neural tissue. The plausible causes of NTDs in NOD mouse embryos were discussed based on these findings.
ABSTRACT Yellow KK mice have the A? allele and spontaneously develop non-insulin dependent diabetes mellitus (NIDDM). In the present study, female yellow KK mice were mated at 7 or 13 weeks of age (the average blood glucose levels were ca. 260 and 500 mg/dl, respectively), and their fetuses were examined on days 18 or 19 of gestation. The fetuses from 13-wk-old dams were smaller than those from 7-wk-old dams. The average lung weight on day 19 of gestation was slightly greater in the fetuses from 13-wk- old dams than in those from 7-wk-old dams (23.3 vs 21.2 mg). Histologically, alveolar spaces were smaller and alveolar walls were thicker in the fetuses from 13-wk-old dams than in those from 7-wk-old dams. Morphometric analysis revealed that the percentage area of the fetal lung occupied by alveolar spaces was significantly smaller in the former fetuses than in the latter. Day-I5 fetal lungs of KK mice, which do not have the A? allele, were cultured in hyperglycemic media (glucose levels: 400 and 700 mg/dl) for 48 hr. The development of alveoli was inhibited in hyperglycemic media as compared to the development of the lungs grown in the control medium. The inhibitory effect was dependent on the glucose concentration in the media. Thus, it seems that maternal hyperglycemia itself is a major cause of the delayed maturation of the fetal lung in NIDDM mice.
ABSTRACT The teratogenic effects of leupeptin on the rat embryonic heart were exa- mined. Wistar rats were injected with 30 mg/kg of leupeptin, 50 mg/kg of leupeptin, and 2.5 ml/kg of normal saline (control group) on days 9 and 10 of gestation. Term fetal weight was significantly lower in the leupeptin groups than in controls. At leupeptin 30 mg/kg, the resorption rate, incidence of malformation, and incidence of cardiovascular (CV) malformation were 13.2070, 34.8'70, 16.7'70, respectively. At leupeptin 50 mg/kg, the resorption rate, incidence of malformation, and incidence of CV malformation were 19.7%, 81.4070, 36.3'70, respectively. The most common malformations were hydrocephaly, anophthalmia, microphthalmia, VSD, ASD, hydronephrosis, and diaphragmatic hernia. Multiple organ systems were affected. Malformation types were similar to those induced by anti-kidney antiserum (AKS) and trypan blue (TB).
ABSTRACT The adenohypophysis of a newborn with cyclopia was examined by electron microscopy. The hypophysis was normal in size and shape in the present case. Electron microscopy, however, showed degenerating cells in the adenohypophysis. These cells had small number of granules and cytoplasmic organelles, and the concentric membranous structure, but were not considered as necrotic cells. These findings may indicate overproduction of hormones by the damage of the negative feedback system. No remarkable change, however, was observed in the endocrine organs by light microscopy. Thus, the possible disorder of the hormone production might not be severe enough to cause abnormal formation of the endocrine system in the present case.