The morphology of abdominal and inguinal cryptorchid testes in stallions: a light and electron microscopic study.

The research study focused on observing and documenting the differences between abdominal and inguinal cryptorchid testes in young stallions, using both light and electron microscopic techniques. The researchers notably discovered that the abdominal cryptorchid testes were significantly smaller and exhibited distinct pathological conditions compared to their inguinal counterparts.

Experiment Procedure

• The research was conducted on eleven unilateral cryptorchid stallions, between two to three years old. These stallions were castrated at the Louisiana State University Veterinary Teaching Hospital for the study.
• Out of the eleven cases, five were abdominal cryptorchids, while the rest were inguinal.
• Specimens were collected from the side of the cryptorchid testes adjacent to the epididymis (abepididymal).
• The collected samples were then prepared for microscopic examination.

Observations and Findings

• One of the major findings was that the cryptorchid testes were generally smaller than the scrotal testes, with the abdominal testes noted to be one-fourth the size of the scrotal testes.
• Abdominal testes in two cases were found to have cysts filled with straw-colored fluid.
• The seminiferous tubules (part of the testes where sperm are produced) of the abdominal testes were larger than those found in the inguinal testes.
• The epithelial linings (cell layers bounding tissue surfaces) of the abdominal testes’ seminiferous tubules had vacuolated characteristics, lacking more than two layers of undifferentiated cells.
• The interstitial collagen fibers of the abdominal testes were coarse and more abundant compared to the inguinal testes.
• Conversely, the seminiferous tubules of the inguinal testes were smaller and featured many epithelial cell layers. These layers were observed at different stages of embryological differentiation and had scattered primordial germ cells (cells that will develop into sperm).
• Necrotic, degenerative changes of the abdominal testes’ epithelial cells were distinct and visible, while the inguinal testes exhibited healthy cells at embryological arrest (a stage indicating the cessation of growth or development).

Conclusion

• The study concluded significant differences between abdominal and inguinal cryptorchid testes in stallions, both in terms of size and cellular characteristics. These findings can provide significant insights into the pathology of cryptorchidism in horses and possibly other species, with potential implications for diagnosis and treatment.