Age-related morphological and functional changes in the Leydig cells of the horse.

This research study explores the age-related changes in Leydig cells of horses. Specifically, the research shows that these cells evolve over time, both in their structure and function.

Types of Leydig Cells

• The research identified two distinct types of Leydig cells in the equine testis through ultrastructural observations. These cells are termed ‘postpubertal’ and ‘adult’.
• The adult testis displays both these types of Leydig cells. In contrast, the testis of the pubertal horse typically exhibits only the postpubertal type, while the aged horse only contains the adult type.

Leydig Cell Populations in Testicular Preparations

• The study showed that despite the age-related morphological changes, Percoll-purified testicular preparations from horses of varying ages (pubertal, adult, and aged) all demonstrated two distinct Leydig cell populations.
• This suggests the presence of the two types of Leydig cells across different life stages of the horse, albeit in differing proportions.

Quantitative Distribution and Functional Characteristics

• The study also investigated the function and distribution of these Leydig cell populations. This was determined primarily by the cells’ ability to bind human chorionic gonadotropin (hCG) and their enhanced testosterone production upon hCG stimulation.
• The analysis revealed differences based on the age of the horse, indicating a shift in the distribution and functional capability of the Leydig cells over time.

Conclusions

• The research concluded that Leydig cells in horses originate from two separate postnatal generations, which are redundant and consecutive in nature.
• The researchers note that there is no strict correlation between the functional properties and the morphological characteristics of these cells. In other words, the observed structural changes in Leydig cells do not correlate directly with their changes in function.