Polyorchidism in a young Sprague-Dawley rat.

Duplicate testes lined in series were observed in the right scrotum of a 6-week-old Sprague-Dawley rat in a single-dose toxicity study. Of the two right testicles, one was spherical and less than half the size of a normal testis. The other was oval-shaped, slightly smaller than a normal testis, and possessed clear, tortuous blood vessels similar to those of a normal testis. Each right testis was grossly separated but faced the intertesticular adipose tissue and was sparsely joined by thin cord-like structures. Only one epididymis covered or encompassed the two right testes. The caput epididymis was attached to the smaller spherical testis, whereas the cauda epididymis was attached to the oval testis. Histopathological examination revealed that the smaller spherical testis on the right side and the testis on the left side were normal. The oval-shaped testis on the right exhibited markedly dilated degenerative seminiferous tubules with one to two layers of Sertoli or germ cells, and almost no spermatogenesis was observed. Multinucleated germ cells were observed in the lumen of the degenerated seminiferous tubules. The right epididymis was morphologically normal and contained few sperm in the epididymal duct of the tail. The cord-like structures between duplicate testes comprised fibrous and adipose tissues. Single efferent ductules, ectopic cartilage, and skeletal muscle tissues were buried in the adipose tissue. To our knowledge, this is the first report of spontaneous polyorchidism in a rodent.

Suspected spontaneous hyperadrenocorticism in a young experimental beagle dog.

A 6-month-old female beagle dog, assigned to the low-dose group in a toxicity study, was evaluated for compound toxicity, and spontaneous hyperadrenocorticism was suspected. The animal had an externally apparent distended abdomen on clinical examination upon arrival. Pre-dose clinical pathology showed slightly higher erythroid parameters and stress leukogram on hematology; plasma biochemistry showed higher total protein, gamma-glutamyl transferase, total cholesterol, and triglyceride levels than the reference data. On necropsy, a prominent increase in adipose tissues of the subcutis and abdomen and increased weight of the adrenal gland and liver were observed. Histopathology revealed diffuse hyperplasia of adrenocortical cells in the zona fasciculata and reticularis, cortical atrophy of the thymus, and abundant glycogen accumulation in the hepatocytes. These findings were incidental and not test-substance-related. Electron microscopy of the adrenocortical cells in the zona fasciculata revealed decreased typical translucent lipid droplets, increased electron-dense lipid droplets, and abundant smooth endoplasmic reticulum and lysosomes. Additionally, increased numbers of various sizes and forms of mitochondria with tubular, vesicular, or lamellar cristae compared to that of normal animals were observed. These ultrastructural characteristics of the adrenocortical cells suggested hyperfunction. The pre-dose plasma cortisol levels were slightly higher than those of other females assigned to the toxicity study, while plasma adrenocorticotropic hormone levels were within the normal range. These findings indicate that hyperadrenocorticism is a possible cause of the systemic changes in this case.