It is generally agreed that complete mixing of the indicator is one of the most important factors of the indicator dilution method, however, no clear definition of the mixing state has been established. We established a formula for the mixing rate of the indicator by the indicator dilution method, using the concept of entropy in the information theory, and compared the mixing rate of indocyanine green in one mixing chamber (left ventricle) with that in the two mixing chamber system (including the aortic system). The mixing rate of the indicator (M) is shown as M(%)=100 H/Hcm -100 (lk Σn i=1 Ci log Ci +log k) (l & k: correction factors in each dye dilution curve, C: mean concentration of the indicator in the region). Left heart and aortic catheterizations by retrograde femoral and carotid artery approach were performed in five anesthetized dogs. Simultaneous dye dilution curves were recorded at the aortic root and at the bifurcation of the abdominal aorta, following the injection of indocyanine green (2.5 mg/lml of indocyamine green for each injection) by impulse into the left ventricle at the endsystole, triggered on the R wave of ECG, using the automatic injector devised by the authors. Twenty-five pairs of dye dilution curves were obtained by simultaneous recording in the aortic root and the abdominal aorta under several hemodynamic conditions, and the cardiac output, mean circulation time and the mixing rate of the indicator were determined. The mixing rate of the indicator obtained in the aortic root (mean±SE: M=78.7 ± 3.43%) was observed to be significantly greater (P<0.01) than in the abdominal aorta (mean ±SE: M=70.0±3.51%). Taking the mixing rate of the indicator into consideration, the cardiac output determination by the indicator dilution method is more sensitive to the changing hemodynamic conditions when determined in the aortic root than in the abdominal aorta.

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In the early embryos of the ascidian (Halocynthia roretzi), regional cytoplasmic differences arise just after fertilization. We successively studied the characteristic features of the cytoplasm of those regions in the embryonic cells during the entire ontogenic process from the unfertilized egg to the tadpole larva. The embryos and larvae were fixed in a mixture of osmium and glutaraldehyde, and the distribution of the organelles in the entire cytoplasm was observed with light and electron microscopy. According to the analysis of the distribution density of the organelles which occupied a given area of the cytoplasm on the section, we introduced the “organelle region” in the cytoplasm and further calculated the approximate area ratios of the “organelle regions” in the cytoplasm of each cell lineage. As a result, it was demonstrated that the characteristic distribution mode was already present in the cytoplasm of the cell lineages of the 8-cell-stage embryos. The features of the cytoplasm in each embryonic cell lineage, moreover, reflected those of the corresponding larval tissue. Our results not only demonstrate that the structural tissue specificity is expressed at an extremely early stage during the ascidian embryogenesis but also suggest that the corresponding functional differentiation among the cell lineages occurs early.

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We observed the ultrastructual features of the cytoplasm in the cell lineages of the cleavage-arrested embryos of the ascidian, Halocynthia roretzi, and compared them with those of the cytoplasm in the corresponding cell lineages of the normal embryos or in the corresponding tissues of the normal larva, in order to examine the presence or the degree of the cellular differentiation without the cleavage. The cleavage of the embryos was arrested by the cytochalasin B at the 16-cell stage and the embryos were cultured in sea water containing cytochalasin B until the developmental time equivalent to the hatching of the control larva. As a result, the cytoplasmic components in the cleavage-arrested 16-cell embryos resembled those observed in the corresponding tissues of the normal larvae, especially in the b5.3 and b5.4 blastomers (epidermal lineage cells) and in the B5.1 blastomeres (which give rise to the endodermal, mesenchymal and muscle cells) but they were less uniforml y organized and their polarity or orientation was very random and irregular, compared with those in the normal larvae. These results demonstrated that the morphological differentiation similar to the larval tissue differentiation could proceed even in the cleavage-arrested embryos to a certain extent.

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Two rare cases of autopsy and surgery presenting extrahepatic biliary obstruction due to intrabile-duct growth of hepatocellular carcinoma were reported. Clinically obstructive jaundice was predominant in comparison with the other symptoms in both cases. In one autopsy case, hepatocellular carcinoma developed in the right lobe of the cirrhotic liver (posthepatitic). It involved the secondary branch of the right hepatic duct and grew into the common hepatic duct. In the other case of surgical operation, hepatocellular carcinoma, which developed in the posterior portion of the right lobe of the cirrhotic liver (posthepatitic), destroyed the posterior wall of the bifurcation of the bilateral hepatic duct and obstructed the common hepatic duct due to the intraductal cancer growth. From the site of the bile duct invasion or permeation by the tumor, two cases were classified into the peripheral (the former case) and proximal (the latter case) types, respectively. Furthermore, as far as obstructive jaundice is clinically concerned, the possibility should be kept in mind that hepatocellular carcinoma may proliferate into the large bile ducts, apart from that of cholangiocarcinoma or cholelithiasis.

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