Annual cycle of the Sertoli cell population in adult stallions.

The research article investigates the annual cycle of the Sertoli cells, a type of cell present in the testes, in adult male horses. The study found a significant variation in the number of Sertoli cells depending on the time of year, with higher counts appearing during the breeding season.

Methods and Experiment Structure

• The researchers used stereological methods in two separate experiments on adult stallions, aiming to confirm the seasonal variation in the number of Sertoli cells and to characterize the annual cycle of the Sertoli cell population.
• The first experiment involved the comparison of testes from two separate groups of 28 adult horses, each aged between 4-20 years. One group was tested during the non-breeding season (December-January) and the other during the breeding season (June-July).
• The team calculated the number of Sertoli cells based on nuclear volume density, parenchymal volume, and the volume of an individual Sertoli cell nucleus. The latter was determined either by reconstruction from serial sections or through average height and width measurements.

Findings From The Experiments

• The results from the first experiment showed that the number of Sertoli cells per testis was significantly greater during the breeding season.
• In the second experiment involving 43-48 adult horses in each 3-month period, results showed that the number of Sertoli cells was higher in May-July than in other periods, and also significantly higher than in November-January.

Conclusion

• Overall, these combined studies confirmed the existence of seasonal differences in the count of Sertoli cells per testis, defining the annual cycle of the Sertoli cell population in adult stallions. Identifying and understanding this pattern could potentially be important for the management of their breeding cycles.