A 50-year-old male presented with signs and symptoms of restrictive hea disease. A right ventricular endo-myocardial biospy revealed deposition of extracellular eosinophilic hyaline material. On transmission electron microscopy, this material is most likely to reveal the presence Of-

Ans. is 'a' i.e., Non branching filaments of indefinite lengtho Restrictive cardiomyopathy along with deposition of extracellular eosinophilic hyaline material suggest the diagnosis of Amyloidosiso Myocardial involvement with amyloid is a common cause of secondary restrictive cardiomyopathy. Amyloid is a pathological proteinaceous substance deposited between cells in various tissues and organs of the body.o With the light microscopic and standard tissue stains amyloid appears as an amorphous, eosinophilic, hyaline extracellular substance, that with progressive accumulation ancroaches on and produces pressure atrophy of adjacent cells.