Presence of type C virus particles and their aberrant form in mammary carcinoma of a strain C58 mouse.

Detailed morphologic characteristics of type C virus particles observed in an X-ray-induced C58 mammary tumor and its transplants have been described. The particles are round and 75 to 100 mμ in diameter, containing an electrondense nucleoid 60 to 70 mμ in diameter. By the negative staining, they do not show obvious spines. Two abnormal types of particles, i. e. cylindrical and aberrant forms have been observed. ∗PMID: 4292109 [PubMed indexed for MEDLINE] Copyright c ©OKAYAMA UNIVERSITY MEDICAL SCHOOL Acta Merl. Okayama 20, 155-158 (1966) PRESENCE OF TYPE C VIRUS PARTICLES AND THEIR ABERRANT FORM IN MAMMARY CARCINOMA OF A STRAIN C58 MOUSE Shinya SUZUKI, ?:ensuke OTA and Kiyoshi HIRAKI Department of Internal Medicine, Okoyama University Medical School Okayoma, Japan (Director: Prof. K. Hiraki) Received for publication, May 20, 1966 Type B virus particles have been demonstrated in mammary tumors of various inbred mouse strains by electron microscopy and considered to be the causative agents of the tumors. Authors have recently reported that type C virus particles, resembling mouse leukemia particles were found in mammary carcinoma arising in a high leukemic strain C58 mouse after X-ray irradiation. HAIRSTONE and associates have observed similar virus particles in mammary tumors of strain A mice. They have, however, assumed that particles in the strain A tumors represent an immature form of the standard B particle, since the size of the total particle is larger than leukemia particles and it has 100 A spines on the envelope as revealed by negative staining. The present paper is concerned with further detailed morphologic study on virus particles in the strain C58 mammary tumors. MATERIALS AND METHODS The origin of the present tumor has been described in the previous paper• The tumor has been maintained by serial subcutaneous cell-graft in C58 mice less than 4 months old. Tissues from the original tumor and its transplants of the 1st to 7th generation were prepared for electron microscopy. They were fixed in buffered 1% osmium tetroxide solution, dehydrated in graded alcohol solutions, embedded in a mixture of methyl and butyl methacrylates and sectioned with a Leitz ultramicrotome. Thin sections were double stained in saturated uranyl acetate solution and in Raynold's solutionS. For negative contrast electron micrographs, virus particles were examined ~ccording to the method described by PARSONS• RESULTS Figure 1 illustrates an acinar space of the original tumor filled with numerous virus particles and fibrils. An epithelial cell with microvilli lies at lower 155 1 Suzuki et al.: Presence of type C virus particles and their aberrant form in Produced by The Berkeley Electronic Press, 1966 156 S. SUZUKI, Z. OTA and K. HIRAKI 2 Acta Medica Okayama, Vol. 20 [1966], Iss. 4, Art. 2 http://escholarship.lib.okayama-u.ac.jp/amo/vol20/iss4/2 Type C Virus in Mammary Carcinoma 157 portion of the field. The particles consist of a moderately electron-dense, centrally located nucleoid 60 to 70 mp. in diameter, contained within a dense shell ranging 75 to 100 mf!. in diameter. Similar virus particles have been observed in transplants of all generations. However, neither extracellular type B or intracellular type A virus particles have been encountered. Figure 2 shows virus particles at higher magnification. A few spines 100 A long are seen covering the external coat of the particles. When negatively stained, the particles are round, ranging 100 to 190 m,l. in diameter and do not show obvious spines on the envelope (Fig. 3). Some of them display an empty center corresponding to the nucleoid. Figure 4 illustrates the profiles of cylindrical forms of the virus present in a degenerated portion of the transplant of the 3rd generation. They are composed of an outer membrane approximately 90 mll. in diameter and an internal dense structure about 60 mll. in diameter. They extend to more than 400m,fl in length. Figure 5 shows virus particles with an unusual internal structure. These particles contain a few dense fibrils instead of the nucleoid. A similar particle is seen in Fig. 1.