Red-tailed hawks were exposed to sublethal levels of lead acetate for periods of 3 or 11 weeks. Alterations in the heme biosynthetic pathway were demonstrated after the first week of exposure to 0.82 mg lead per kilogram body weight per day. Activity of erythrocyte porphobilinogen synthase (aminolevulinic acid dehydratase) was depressed significantly and did not return to normal levels until 5 weeks after the termination of lead treatments. A rapid and relatively brief increase in erythrocyte free protoporphyrin and a slower but more prolonged increase in its zinc complex were also demonstrated with exposure to this dose of lead for 3 weeks. Less substantial decreases in hematocrit and hemoglobin levels occurred but only in the longer experiment with exposure to higher lead levels. Short term, low level lead exposure did not effect immune function significantly in the hawks, as measured by antibody titers to foreign red blood cells or by the mitogenic stimulation of T-lymphocytes. Increased lead exposure produced a significant decrease in the mitogenic response but had no effect on antibody titers.

A total of 33 methylcholanthrene-induced sarcomas, growing in C57BL/6J or BALB/cByJ mice, were tested for their immunogenicity and for their relative macrophage content. No relationship was demonstrated between these two characteristics. These results suggest that the direct correlation between macrophage content and immunogenicity demonstrated in rat tumor model systems may not hold for other systems.

Ten mouse strains in which aryl hydrocarbon hydroxylase can be induced, or F1 hybrids of these strains, were ranked according to their sarcoma susceptibility when exposed to a high concentration (5 percent) of the chemical carcinogen 3-methylcholanthrene. This rank order was reversed when the concentration of 3-methylcholanthrene was reduced to 0.05 percent.

Five tumor cell lines that originated from a single mouse mammary adenocarcinoma, normal mammary tissue, a preneoplastic alveolar nodule line, and a tumor developing spontaneously from that preneoplastic line were used to study the different three-dimensional growth patterns that mammary tissues produce in collagen gel. We describe five different outgrowth morphologies, one of which may represent normal stromal tissue and infiltrating cells. One type was produced both by tumors and by normal mammary gland tissue in an age-related fashion, i.e. more outgrowths of this type were produced by mammary tissue from older mice. The outgrowth patterns for the tumor cell lines were not related to morphology in monolayer culture. Certain of the tumor lines, including one variant-producing line, produced multiple outgrowth patterns. Our results indicate that this cultivation technique may be a useful method for studying the heterogeneity of mammary tumors and may facilitate the isolation of mammary tumor subpopulations.

Tibial dyschondroplasia was induced in female broiler chicks by the incorporation of 2% Fusarium roseum "Alaska" culture into their starter ration. Chicks were placed on this diet at one day of age and maintained until they were killed at four days or one week. Proximal tibial physes were grossly thickened into cone-shaped masses of cartilage by one week of age. Microscopically, lesions were in both ages of treated chickens and were characterized by thickening of the transitional zone which was especially prominent in the center of the growth plate. This zone was unmineralized, avascular, and contained chondrocytes which were crenated and densely eosinophilic. The cartilage matrix was pale and contained some patchy eosinophilic foci. Four growth plates with tibial dyschondroplasia and four normal growth plates from each of the four-day and one-week-old age groups were evaluated based on the following parameters: number of metaphyseal vascular sprouts, distance between the proliferative/transitional junction and the tip of the metaphyseal vascular sprouts, width of the tips of the metaphyseal sprouts, distance between tips of adjacent metaphyseal vascular sprouts, and number of perforating vessels in the proliferative zone. The distance between the proliferative/transitional junction and the metaphyseal sprout tips was greatly increased (p less than 0.01) in the affected four-day and one-week-old chickens compared to age-matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)