Four cases of adenoacanthoma of the pancreas were collected and the literature reviewed. This uncommon histologic variant appears as aggressive and malignant as the more common adenocarcinomas. Two of these four cases had originally been diagnosed as squamous cell carcinomas and were shown to be adenoacanthoma in type after additional sections were examined microscopically. It is the authors' opinion that any squamous cell carcinoma of the pancreas must be thoroughly examined for adenocarcinomatous elements before it can be classified as being pure squamous in type. Also, because metastases may be predominantly of either squamous or adenomatous type, the presence of squamous carcinoma in a metastatic lesion does not eliminate the possibility of a pancreatic primary nor does the finding of two distinct histologic types of metastases necessarily imply two separate primary malignancies. The terminology and origin of this histologic type of pancreatic tumor are discussed.

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Using mainly rabbits and rats investigations on the endothelial permeability of the aorta, on relation between thrombus formation and endothelial damage, and on tissue culture of the endothelial cells of the rabbit aorta have been carried out. The permeability of endothelial layer of rabbit aorta Increased by cholesterol‐feeding. This seems to be derived from morphological and functional disorder of the endothelial cells. As a hemodynamic effect of blood flow, increased permeability of the endothelium of rat aorta was also found in experimental renal hypertension. Accumulation of blood‐plasma components (edema) was seen in the subendothellal area in cholesterol‐fed rabbit aorta and in hypertensive rat aorta. Long‐standing subendothellal edema is considered to be the cause of fibrous intlmal thickening (Grade I lesion/Nakashlma). Endothelial defect of the aorta due to various damages is related to thrombus formation, and this seems to be accelerated by cholesterol feeding. Morphological differences between normal endothelium and that of atherosclerotic lesion in human and in rabbit aortas can be seen. Tissue culture of the endothelium was performed in vivo and in vitro, and some discussions were made on the characteristics of cultured endothelial cells.