The postnatal development of myocardial cells in the bilateral atria and ventricles of rats at days 1, 10, 20, 30 and 60 was studied by means of an ultrastructural quantitative method. No clear differences between the right and left myocardium were found throughout the developmental period or in the adult stage. The myocardial cells increased in thickness more rapidly up to day 20 than during the subsequent period. Myofibrils occupied about 50–60% of the cytoplasm of almost all kinds of cardiac muscle cells except those of the newborn atrium. The fraction of mitochondria increased after day 10, whereas that of glycogen conversely decreased. Although the presence of specific granules characterized the atrial myocardial cells even in newborns (day 1), no differences in other cellular components or fiber thickness between the atrium and the ventricle were seen at this stage. The distinction between atrial and ventricular muscle cells, in terms of fiber thickness, mitochondrial and glycogen content, began to appear at day 10 and became increasingly prominent with age until virtually all muscle fibers reached an almost mature state at day 20.

We describe a very rare case of synchronous mucinous tumor of the endometrium and ovaries presenting during ovulation induction. A 31-year-old woman received ovulation induction for 5-year primary infertility. Ultrasonography revealed mucus retention in the uterine cavity and bilateral multicystic ovaries during ovulation induction. Atypical hyperplasia was diagnosed by endometrial curettage. Repeated procedures including ovarian cystectomy, endometrial curettage and in vitro fertilization combined with progestine therapy resulted in no pregnancy but rapid recurrences. She finally underwent simple hysterectomy and bilateral salpingo-oophorectomy. Microscopic examination revealed mucinous cystadenoma in the both ovaries and well differentiated mucinous adenocarcinoma of the endometrium.

Not only the cartilage of the capitellum but the cartilage of the radial head are acoustically degenerated in osteochondritis dissecans patients. Plugs might be damaged in the transplanting procedure, and further follow-up is necessary.

Ultrastructural differentiation of cardiac muscle cells in the bilateral atria and ventricles of the cat at 1, 16, 25 and 40 days and 6 months after birth was studied by morphometry on electron micrographs. At the newborn stage, no T-tubule was found in the ventricular muscle cells, but specific granules were already noted in the atrial myocytes. The cell diameter of the ventricular myocardium was greater than that of the atrium at this stage. The T-tubule was first recognized in the ventricular muscle cells at day 16, at which stage the area occupied by the mitochondria and glycogen in the atrial muscle cells was definitely found to differ from that in the ventricular muscle cells. Thereafter, the differences in the ultrastructure between the atria and ventricles became more remarkable, particularly in the cell diameter and in the mitochondrial area. The cat cardiac muscle cells are characterized by numerous lipid droplets within the cytoplasm in contrast to those of the rat and the guinea pig.