Cryptorchidism is one of the most common
genital defects in
dogs. This study investigated the effects of
abdominal cryptorchidism on morphology,
cell proliferation, and
Sertoli cell condition in a
dog with spontaneous
unilateral cryptorchidism. Elective
orchidectomy was performed on the abdominal right
testis and the scrotal left
testis. Significant reductions in numbers of
spermatogonia,
spermatocytes, and
spermatids were observed in
hematoxylin and
eosin stained sections of the cryptorchid
testis. The size of the epididymal duct was smaller than that of the control
testis. Based on Ki67
immunohistochemistry, the proliferative activity of
spermatogonia and
spermatocytes was significantly decreased in the cryptorchid
testis. However, proliferative activity was increased in the epididymal duct. Based on GATA-4
immunohistochemistry,
Sertoli cells were relatively resistant to
cryptorchidism, and the proliferative activity of
Sertoli cells was markedly increased in the cryptorchid
testis than in the control
testis. These results suggest that spontaneous
unilateral cryptorchidism causes morphological defects in
spermatogonia and
spermatocytes in the
testis and changes the size of the efferent ductule of the
epididymis. In addition, spontaneous
unilateral cryptorchidism increases proliferative activity of
Sertoli cells, which may be a
predisposing factor for
Sertoli cell cancer in cryptorchid
testes.