Vascularization and Production of Mitogenic Factor(S) in Domestic Cat (Felis catus) Testes: Preliminary Results

Some male seasonal breeders are known to undergo testicular growth and regression throughout the year. The periodic and fast physiological development and regression processes, with simultaneous fast changes in blood flow, appears to be stimulated by angiogenic substances and inhibited by anti-angiogenic factors. The objective of this study was to evaluate the effect of season on microvascularization and production of angiogenic factors by testicular tissue, using the male cat as a model. Monthly, testes were collected post mortem from domestic stray cats, for histology and for tissue culture. Testis explants were cultured for 18h and conditioned media were tested for their ability to stimulate mitogenesis of bovine aortic endothelial cells (BAEC). Vascular endothelial growth factor (VEGF) was used as a positive control. Proliferative response of BAEC to samples was evaluated by determining the number of cells in each well using a Neubauer chamber. Vascular density was assessed by a computerized image analysis ('Scion Image, NIH, USA') based on the total histological area occupied by the vascular lumen. Percentage data subjected to arcsine transformation were analysed by one-way ANOVA and post-comparison tests. There was a significant increase in microvascular areas in November ( P  < 0.001), when compared to the remaining months (LSD test). All cat testicular tissue showed the capability to increase BAEC proliferation, when compared to negative controls, throughout the study. However, there was an increase in BAEC mitogenesis in February ( P  < 0.05) and November ( P  < 0.001), when compared to the other months. Our data show that cat testicular tissue from different periods of the year stimulates angiogenic factor(s). Furthermore, changes in angiogenesis may play a role on vascular growth and regression of the testes during the breeding and non-breeding season in the male cat.