Description
A peculiar hyaline sarcoplasmic inclusion in the atrial myocytes of old female Syrian hamsters is described. This type of inclusion resembles that described in rare human cardiomyopathy. They have also been described in other rodents and have been speculated eventually to contain atrial natriuretic factor (ANF). The present study demonstrated that they are fibrillar in nature, however, and do not contain ANF-immunoreactive product. Because their morphologic aspect is analogous to that described in human heart and in the pathology of other contractile tissues, it is suggested that they probably consist of intermediate filaments and/or associated macromolecules.