Note on Nucleolonemata in Human Cultured Cells

In the course of treatments of cultured cells with a hypotonic salt solution to spread the chromosomes (after Hsu, 1952; Hsu and Pomerst, 1953), certain filamen-tous structures were seen by phase contrast microscopy within the nucleoli of living normal and neoplastic human so-matic cells. Such indications of filaments in nucleoli seem of some interest in relation to earlier reports of similar observations following the use of other materials and of widely different techniques. Thus, filamentous structures have been described within the nudeoli of a variety of plant and animal cells processed by spe-, and similar observations have also been reported for certain germinal cells examined in v/no. Detailed descriptions of such coiled structure in stained nudeoli of several Conjugales have also appeared (God-ward, 1950). Independent electron microscopic observations of such structures in the nucleoli of various rodent and human cells have also been reported (Borysko and Bang, 1951; Bernhard eg a/., 1951 and 1952). These filaments seen by the special techniques of electron microscopy are of about the same size as those described by the other techniques (0.1 to 0,2 ~ diameter). The present observations with living and mildly treated human cells (of. Hughes, 1952) thus support the reality of the nucleolonema and call for studies of its nature and function in normal and neoplastic human cells. For these studies, pieces (1 to 3 ram.) of tissues from flourishing cultures of minced human embryo and of two human epidermoid carcinomas (HeLa and Helleis),x or from heterologous propagation of a human epidermoid carcinoma (HEp 3) and of a human sarcoma (H.S. I) in rats 2 were planted on coverslips in clots composed of equal parts of chicken plasma and culture fluid, s These cover-slip cultures were then placed in roller tubes and fed with 1 ml. of culture fluid initially and every 3rd day thereafter. Incubation was at 37°C. After2 to 6 days' growth, the cultures were pretreated for various times by immersion at 37°C. in a hypotonic salt solution comprising 20 parts of Gey's standard salt solution and 80 parts of a solution with the same ingredients except for NaC1 which was omitted. Following this pretreatment the coverslips were mounted in a drop of the hypotonic solution, sealed with paraffin, and examined immediately and at frequent intervals on a warm-stage phase l We are greatly indebted to Dr. Audrey Fjelde for these cultures. s We are greatly indebted to Dr. …