Date Published: February 8, 2012
Publisher: Hindawi Publishing Corporation
Author(s): Graça Alexandre-Pires, Luísa Mateus, Catarina Martins, Graça Ferreira-Dias.
Some male seasonal breeders undergo testicular growth and regression throughout the year. The objective of this study was to understand the effect of seasonality on: (i) microvasculature of cat testes; (ii) angiogenic activity in testicular tissue in vitro; and (iii) testicular endothelial cells expression throughout the year. Testicular vascular areas increased in March and April, June and July, being the highest in November and December. Testes tissue differently stimulated in vitro angiogenic activity, according to seasonality, being more evident in February, and November and December. Even though CD143 expression was higher in December, smaller peaks were present in April and July. As changes in angiogenesis may play a role on testes vascular growth and regression during the breeding and non-breeding seasons, data suggest that testicular vascularisation in cats is increased in three photoperiod windows of time, November/December, March/April and June/July. This increase in testicular vascularisation might be related to higher seasonal sexual activity in cats, which is in agreement with the fact that most queens give birth at the beginning of the year, between May and July, and in September.
The study of the vasculature of the testis has attracted scientists’ attention for many centuries, especially at the end of the 19th and throughout the 20th century. This research has been performed in a large variety of animal species such as rat, mouse, rabbit, guinea pig, dog, ram, bull, boar, horse, marsupials, man, and other primates [1–4]. It has been long known that the physiologic role of the pampiniform plexus, on thermoregulation of the testes. This is a highly efficient countercurrent heat exchanger in which the arterial blood is precooled before it reaches the testis, while venous blood is warmed to body temperature before it returns to the abdomen . It is nevertheless very rare to find references on the vasculature of cat testes (Felis domesticus).
The formation of new blood vessels from a preexisting vasculature, known as angiogenesis, is a quite infrequent process in adult mammals as a physiologic process. Both angiogenic and antiangiogenic factors play a regulatory role on angiogenesis [7, 31]. In the female reproductive tract during the ovarian/uterine cycle it occurs as physiologic changes [10–13], as well as in the male reproductive tract during gonadal recrudescence in seasonal breeders [14, 24, 32, 33].