The impact of physical activity on carcinogenesis has been demonstrated in many studies. Taking into account the discrepant results of physical exercise on the cell proliferation and apoptosis of breast cancer, we aimed to examine the impact of physical training on N-methyl-N-nitrosourea-(MNU)-induced mammary carcinogenesis. Fifty female rats were divided into four groups according to the intensity of physical activity they undertook. The number of developed tumors, tumor volume, and histopathological diagnoses were noted. Apoptosis and cell proliferation were studied by the number of TUNEL-positive and Ki-67-expressing cells. We demonstrated a statistically significant decrease in the tumor number between all trained groups and the control group. The results were most pronounced in the group with a moderate intensity of training. Moreover, we showed a decrease in tumor volume as training intensity increased, though the differences were not statistically significant. The mean number of TUNEL-positive cancer cells was significantly higher in the training groups than in the control group. These data suggest that physical training, especially of moderate intensity, may alleviate MNU-induced mammary carcinogenesis. The results could suggest that physical exercise-induced apoptosis may be a protective mechanism.

This study aims at presenting histology of growing and mature antlers in red deer stag (Cervus elaphus). Growing antlers constitute a model organ for examining regeneration processes of tissues because they are the only mammalian appendages capable of regeneration. Histological study revealed that the tip of a growing antler consists of hairy skin, perichondrium, mesenchyme and chondroprogenitors area. By performing immunochistochemistry, we found that cell expressing Ki-67 and PCNA antigens were localized in basal layer of epidermis, skin glands and beneath their secretory sections, mesenchyme as well as within and in the vicinity of central blood vessels. Ultrastructurally, cells from chondroprogenitors zone have chondroblast-like morphology and take part in producing of collagen fibres followed by the process of cartilage mineralization. However, mature antlers also consist of lamellar osseous tissue.

Implanted antlerogenic cells were not rejected and possibly took part in the reconstruction of missing sections of the scaffolding of the rabbits' ear cartilages (although the mechanism is yet unknown). Low immunogenicity of AC, simplicity, efficiency, and low costs of production of implant material are the benefits of this method. Further research should unequivocally answer the question whether the MIC-1 cells are or are not the long-sought-after ideal material for the reconstruction of cartilaginous tissue lesions in various species, including human.

Our findings indicate that the use of both antlerogenic stem cell implants and the preparations derived from the cells offer alternative approaches to those based on autologous stem cells in the biological stimulation of osteogenesis and in bone regeneration.

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