ABSTRACT
4 female Wistar rats,weighing 287.5?21.7 gms,about 7～7.5 months old,were used.Using ~3H-TdR and ~(14)C-TdR as labels, double labelling method was employed. The dose of ~3H-TdR used was 1 ?Ci/gm body weight and that of ~(14)C-TdR used was 0.125 ?Ci/gm body weight. Bone marrow smears of both femurs were made and autoradiographs were coated with No. 4 liquid nuclear emulsion.The following results were obtained:In erythropoietic series: Nc/N_H=5.0?1.0, LI=62.3?17.9％, MI=3.4?1.9％. According to the above figures, by calculation, we obtained the cell cycle time and the duration of 4 phases as follows: TG_1≤4.3 hrs,Ts=5.0 hrs, TG_2≥1.0 hr, Tm=0.4 hr and Tc=10.7 hrs.In neutrophilic granulopoietic series: Nc/N_H=3.9?0.9, LI=45.3?5.3％, MI=3.3?1.4％. According to the above figures, the following parameters of the cycle. were obtained as follows: TG_1≤5.6 hrs, Ts=3.9 hrs, TG_2≥1.0 hr, Tm=0.4 hr and Tc=10.9 hrs.There was no obvious difference of Tc between the erythropoietic series, and theneutrophilic granulopoietic series in rats, but significant difference of Tc between them in mice.
ABSTRACT
Studies were carried out on the incidence of SCE and chromosomal aberrations in primary cultured cells of mouse embryo exposed to ~(60)Co-? rays and/or treated with chemical carcinogen——benzopyrene.Result shows in the cultured cells exposed to ~(60)Co-? rays at 50 rads, as compared wtih controls there was no statistically significant change in the frequencies of the appearance of both SCE and chromosomal aberrations, In the cells, however, exposed at 300 rads, the frequencies of SCE and chromosomal aberrations were about 1.3 and 24 times higher than that in the unirradiated controls respectively. In the cultured cells treated with 0.05?g of benzopyrene per millilitre of culture medium, the frequency of SCE were increased by about 1.8 times of that of the control group, while the change of chromosomal aberrations had no statistical significance.From the above results, it was suggested that SCE was proved to be a sensitive indicator for evaluating the effects of chemical carcinogens. There is a remarkable difference existing between the frequencies of SCE and chromosomal aberrations induced by ionizing radiation and chemical carcinogens. The difference seems to have a certain relation to their differences in carcinogenic mechanism and effects on carcinogenesis.It was noted that there are some advantages to utilize primary cultured cells of mouse embryo as target cells.
ABSTRACT
The distributions of estrogen receptors in preoptic region of hypothalamus, anterior lobe of pituitary gland, mammary gland, thymus and liver of LACA and C57 BL strains of mice were studied by ~3H-estradiol and autoradiography in frozen sections.In both strains of mice, labelling index (LI) was more than 85％ in preoptic region of hypothalamus and anterior lobe of pituitary gland, and average number of silver grains (AG) was more than 19. LI and AG of epithelial cells of mammary glands in LACA strain of mice were quite high, 96％ and 12 respectively; but in C57BL strain of mice were only 5％ and 5 respectively. A few hepatic cells and lymphocytes of thymus were labelled.According to the above results the reason of why mammary carcinoma of female LACA strain of mice and adenoma of pituitary gland of C57BL strain of mice could 15e easily induced by estrogenic hormones (estradiol valerate and hydroxyprogesterone caproate, EP), but no mammary carcinoma was induced in C57BL strain of mice by EP, and this can be partly explained by the presence of a large or few number of estrogen receptors. However, the presence of estrogen receptors was only a prerequisite but not a unique condition. Other factors should be considered, because many more estrogen receptors were present in preoptic region of hypothalamus of both strains of mice and anterior lobe of pituitary gland of LACA strain of mice, but few or no tumors could be induced by EP.
ABSTRACT
By using double labelling methods with ~3H-TdR and ~(14)C-TdR, autoradiographs were prepared in young (40 days old) and in old (16 months old) male LACA mice and in adult (7～7.5 months old) female Wistar rats to observe the cell cycle time and relevant parameters of dorsal skin and both testes.The following results were obtained:1. In young and old mice, duration of cell cycle (Tc) and relevant parameters of epidermis were as follows respectively: labeling index (LI)=1.0 and 1.5％; mitotic index (MI)=0.4 and 0.4%; duration of DNA synthesis (Ts)=3.5 and 4.2 hours; Tc=20.3 and 17.5 days.In adult female rats, they were 3.0%, 0.3%, 4.7 hours and 8.3 days respectively. Tc of rat epidermis was obviously shorter than that of mouse epidermis (P0.50).