Temporal appearance of seasonal changes in numbers of Sertoli cells, Leydig cells, and germ cells in stallions.

This research article investigates the seasonal changes in the numbers of Leydig, Sertoli, and germ cells in stallions to understand if increased daily sperm production might be related to changes in these testicular cells. The results show that significant increases in the numbers of Sertoli cells and spermatogonia precede the increase in Leydig cells in the breeding season, suggesting that the need to accommodate more spermatogonia might lead to an increase in testicular size and number of somatic cells.

Details of the Research

• The study aimed to evaluate the timing of seasonal variation in numbers of different types of cells involved in sperm production in stallions. The cells studied include Leydig, Sertoli, and germ cells (inclusive of spermatogonia and other germ cells).
• The researchers found that there was a significant incline in numbers of spermatogonia and Sertoli cells leading up to the breeding season. As these increases occurred before a similar increase in Leydig cells, the study suggests that the rise in sperm production potentially drives these changes.

Findings

• Interestingly, the study found that during the breeding season, the change from B spermatogonia to primary spermatocytes was slightly reduced. However, the rate of degradation between types A and B spermatogonia was not affected by the season.
• The biggest changes in cell counts were noted in May and June, with spermatogonia count rising by as much as 2.5 times compared to January. Leydig and Sertoli cells showed increases to the magnitude of 1.5 to 1.9 times.

Interpretation of Results

• The researchers concluded that the increase in the numbers of spermatogonia and Sertoli cells could be a resultant effect of the need to accommodate more progeny of spermatogonia, leading up to an increased testicular size and number of somatic cells.
• The absence of a significant seasonal difference in the ratio of primary spermatocytes per Sertoli cell suggests a limited capacity of individual Sertoli cells to cater to primary spermatocytes.