Previous reports on the ultrastructure of cartilage matrix have described fibers, amorphous ground substance and, in some instances, dense matrix granules. The fibers are presumably collagen, but thc nature of the granules is unknown. The primary purpose of this study has bccn to investigate the ultrastructure of cartilage matrix ih chick cmbryos with particular emphasis on the distribution and composition of these granules. In matrix of the zone of articular cartilage, mature collagen fibers can bc seen but granules are not present. In matrix of all other zones of cartilage, fibers are smaller and granules are present. When the matrix of cpiphyseal cartilage is compared to that of the zone of hypertrophic cells, fibers are similar but the granules in the latter zonc are larger and more numerous. The granules in both zones were digested by hyaluronidase and positive to colloidal iron staining. Chemical analyses of cartilage from these zones indicate the hexosamine and radiosulfate content of the zone of hypertrophic cells to be higher than that of the zone of epiphyscal cartilage. The increased hcxosamine was shown by column chromatography to be principally sulfated mucopolysaccharide, thereby indicating a direct corrclation between size and number of granules and sulfated mucopolysaccharide content in the two zones. Thcsc data and the results of the electron microscopic histochemical studies are consistent with the concept that the granules in cartilage matrix contain acidic mucopolysaccharide.

Anatomic variations of the orifice of the human coronary sinus now have practical significance since the advent of catheterization of the coronary sinus. Six main types of variation of the valve of the coronary sinus of 150 hearts are described. The difficulties encountered in catheterization of the human coronary sinus are probably due to obstruction offered by large membranes, bars and networks, and less frequently due to the presence of a large eustachian ridge. On the basis of this study, catheterization of the human coronary sinus should be possible in a maximum of 75 per cent of the cases.M EASUREMENT of the coronary blood flow and myocardial metabolism-5 has been made possible by the technic of catheterization of the coronary sinus in the intact dog and man. Detailed knowledge of the structure of the right atrium, and particularly of the variations and anomalies of the venous valves of the right atrium of the human heart (eustachian valve or the valve of the inferior vena cava, and the thebesian valve or the valve of the coronary sinus) now has practical significance. The failures reported in a large per cent of the attempts to catheterize the human coronary sinus can be explained on anatomic bases. Since in previous studies8-'0 the anatomic variations of the human coronary sinus were not considered from the viewpoint of their possible influence on catheterization, we believe it desirable to study anew the variations in the orifice of the human coronary sinus in a large series of adult hearts. hearts chosen at random from the large collection of formalin fixed specimens at the Institute of Pathology, Western Reserve University. The hearts had been opened in the customary routine manner, so that the eustachian valve was usually sectioned near the middle by an incision extending between the orifices of the venae cavae. In examining the eustachian valve, special care was taken to reappose the cut edges, and examine its structure from the lateral aspect of the opened right atrium. The thebesian valve and orifice of the coronary sinus were intact in each case. MATERIALS AND METHODSAll descriptions and measurements of the valves were made with the heart held in a position similar to that occupied in the intact body-the superior and inferior venae cavae in an axis parallel to the longitudinal axis of the body, with the longitudinal axis of the heart (base to apex) semihorizontal. Observations made in recent autopsies confirmed the correctness of the above position ( fig. 1). When the free wall of the right ventricle and the anterior lateral aspect of the right atrium are removed from a heart in situ, the following relations are observed: the free margin of the eustachian valve is concave and is directed cephalad, and the attached margins extend roughly from dorsum to ventrum, parallel to the median sagittal plane of the body. The orifice of the coronary sinus is to the left and below the medial extremity of the valve of the inferior vena cava and in the space between the latter and the edge of the right atrioven...

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