Eizo Aikawa

Developmental spectrum of cardiac outflow tract anomalies encompassing transposition of the great arteries and dextroposition of the aorta: Pathogenic effect of extrinsic retinoic acid in the mouse embryo

We previously reported that retinoic acid shows a dose‐dependent differential induction of various cardiac outflow anomalies: transposition of the great arteries is induced mainly by a high dose (70 mg/kg) and dextroposition of the aorta by a low dose (40–60 mg/kg; Yasui et al., 1995). We subsequently delineated the aberrant outflow tract septation process leading to the transposition (Yasui et al., 1997). The aim of the present study was to illustrate a spectrum of developmental abnormalities by examining mouse embryos treated with a low dose of retinoic acid and comparing them with embryos administered a high dose. We employed in situ observation on live embryos to discern the blood flow streams and scanning electron microscopy to clarify the internal structure. The embryos treated with a low dose of retinoic acid showed several basic phenotypes common to the high dose retinoic acid group, although variable and relatively mild, such as hypoplasia and dysplasia in the proximal outflow cushions, decreased counter‐clockwise rotation in the distal outflow tract, and deviation of the edges of the developing outflow septum. In typical cases, the right‐sided edge of the developing outflow septum shifted ventrally by various degrees, allowing for the right ventricle‐to‐aorta pathway, whereas the left‐sided edge preserved the continuity with the interventricular septum, as in the normal embryo. These findings indicate that morphogenesis of dextroposition of the aorta and transposition of the great arteries are not only distinct but also show some basic pathways in common. Anat Rec 254:253–260, 1999.

Radioautographic study on the obliteration of the ductus arteriosus botalli

Durch autoradiographische Untersuchungen wurde gezeigt, daß die Obliteration des Ductus arteriosus Botalli, welche während einer kritischen Zeit abläuft, nicht nur durch die Wandzellen des Ductus sondern auch Elemente des strömenden Blutes getragen wird. Während der Phase der Proliferation besteht eine besondere Störanfälligkeit der Zellen, insbesondere gegenüber Sauerstoffmangel. Es scheint, daß die Suszeptibilität genisch verankert ist. From the findings obtained from the radioautographic study on the obliteration of the ductus arteriosus, the authors confirmed that the obliteration was not caused only by the proliferation of the cells in the intimal layer of the ductus, but rather by the migration of the cells into the lumen. When the embryos reached the final stage of fetal life, their ductus arteriosus possessed a specific property to obliterate after the blood flow ceased. Some discussions are devoted to the etiology of the patent ductus arteriosus.

Fluctuation of fluorescent material in the rat's and human leucocytes under various situation

When modified FALCK-HILLARP technic was applied to blood smears of rat and human specimens, the fluorescence was detected not only in platelets, but in leucocytes. In rat leucocytes and platelets, the bimodal daily rhythm of fluorescent material is observed under physiological condition. The rhythm is modified considerably if animals are exposed to the continuous lighting. The intensity and number of the fluorescent cells in the human smears increased markedly in patients suffering from schizophrenia compared with controls. The content of fluorescent material in leucocytes assumes to be closely related with an activity of the living states.

In vitro characterization of Mato's FGP cells isolated from rat cerebrum

Matos FGP cells surrounding cerebral arterioles play a significant role in the maintenance of a homeostatic microenvironment in the brain. In this study, the perivascular cells were isolated from rat cerebral microvessels and cultured in vitro to characterize their phenotype. Autofluorescence of the intracellular granules in cultured cells and the uptake of HRP and DiI-Ac-LDL by these cells were observed. The cells reacted positively to an anti-scavenger receptor A antibody. Positive immunoreactions of cultured cells to ED1 and ED2 antibodies were observed, whereas they were weak or negative to ED3 and OX42 antibodies. Acid phosphatase activity was detected in the granules of cultured cells. In conclusion, the cells cultivated under the present conditions revealed very similar characteristics to Matos FGP cells in situ and therefore are useful for studies on FGP cells.

Studies on the obliteration of the ductus arteriosus in rat embryos

SummaryWistar rat embryos weighing over 3 g obtained by Caesarean section can adapt to extrauterine life. The ductus arteriosus of such embryos is obliterated within 2 hours after the first breath. However, the d.a. of embryos weighing 3 to 4 g does not obliterate continuously but distends again after about 40 to 60 minutes.The finding is in accordance with the inconstancy of the blood circulation through the vessels in the critical period stated by Doerr. The “inconstancy” of the closing process is characteristic in the ductus arteriosus of premature embryos. Further, it is shown in this study that the degeneration of intimal cells, disruption of elastic lamellae and protrusion of the intimal tissue are essential for the complete obliteration of the ductus arteriosus. In addition, the tonus of the outer circular muscle layers is increased. The degenerative changes in the vascular wall are observed at first in the subendothelial cells, and these cells seem to play a principal role in the modification of the architecture of the d.a. The transformation of smooth-muscle cells and the change of cytoplasmic organelles were characteristic depending on the period after the first breath.The other factors concerning the obliteration of the d.a. are discussed.