Identification of gonadal tissue in cryptorchid stallion can be improved by molecular biological analysis – a case report.

This research outlines a case study on a 2-year-old cryptorchid stallion, where the use of molecular biology in conjunction with traditional histological examinations helped identify the surgically removed testicular tissue, despite its malformations.

Background

• Cryptorchidism is a condition in stallions where one or both testes have not descended into the scrotum from the abdomen, presenting surgical and diagnostic complications.
• Generally, it can be challenging to identify the removed testicular tissue in cryptorchid stallions due to morphological and histological malformations.

Case Presentation

• A 2-year-old Haflinger stallion diagnosed with cryptorchidism was castrated, with a focus on the removal of the left intra-abdominal testis.
• During the operation, the surgeons found a firm, dysmorphic structure in the abdominal cavity that was unidentifiable based on its macroscopic anatomy.

Methods

• The unrecognized tissue was fixed in Bouin’s solution and embedded in paraffin for histological examination.
• Multiple tests were conducted to understand the nature of the tissue better including:
• Immuno-histochemistry for the identification of tubular structures using smooth muscle actin as a marker.
• Reverse transcriptase polymerase chain reaction (RT-PCR) to detect the expression of the steroidogenic acute regulatory protein (StAR), indicative of the presence of Leydig cells, responsible for testosterone production.
• Post-surgery, an hCG (Human Chorionic Gonadotropin) test was conducted to screen for any remaining testicular tissue by checking for a rise in testosterone levels.

Results and Conclusion

• Standard histological examination by haematoxylin and eosin staining showed signs of tissue calcification, amorph matrix with scattered cells, and round structures – the latter of which could not be definitively identified as tubules.
• Actin staining revealed some tubular wall structures, and the presence of StAR mRNA expression indicated Leydig cells in some parts of the removed tissue.
• The post-operative hCG test did not show any increase in testosterone levels, indicating that there was likely no remaining testicular tissue.
• The molecular biological analysis in conjunction with the histological examination help identify the malformed tissue as testes, highlighting its importance in cases where it’s challenging to diagnose such tissues.*/