ESI IN-SITU ANALYSES OF EXTRACHROMOSOMAL RNP GRANULES

Observation of unstained ultrathin sections of salivary gland cells of Chironomus thummi and C. tentans, by means of electron spectroscopic imaging (ESI), has revealed that phosphorus is distributed in two type s of granular structures in the nucleoplasm of these cells. In additio n to a specific type of premessenger ribonucleoprotein (RNP) particle, known as the Balbiani ring (Br) granule, EST revealed a new type of p hosphorus-rich small granular component. Examination of unstained sect ions by energy filtering transmission electron microscopy (EFTEM) offe rs the opportunity of obtaining the signal from the specimen alone, th us avoiding the possible contributions of heavy metals present in any staining product.