Polyorchidism in a young Sprague-Dawley rat

Area of Science:

• Reproductive biology
• Comparative pathology
• Toxicology

Background:

• Rodent models are crucial for understanding reproductive health.
• Spontaneous congenital anomalies provide insights into developmental processes.

Observation:

• A 6-week-old Sprague-Dawley rat presented with duplicate testes in the right scrotum.
• One right testis was small and spherical, the other oval-shaped with visible vasculature.
• A single epididymis enveloped both right testes, with distinct caput and cauda attachments.

Findings:

• Histopathology confirmed the spherical right testis and the left testis were normal.
• The oval right testis showed degenerative seminiferous tubules with limited spermatogenesis and multinucleated germ cells.
• The connecting tissues between testes contained fibrous and adipose tissue, with ectopic cartilage and muscle.

Implications:

• This case represents the first documented instance of spontaneous polyorchidism in a rodent.
• Understanding such anomalies aids in interpreting toxicity study findings and developmental biology.
• Further research may elucidate the genetic or environmental factors contributing to polyorchidism in mammals.