Bulbourethral (Cowper's) gland abnormalities in inbred laboratory mice

Abnormalities of the bulbourethral (Cowper's) glands are rare in most strai ns of inbred laboratory mice. Since the glands are covered with striated mu scle and because of their small size, the bulbourethral glands are often ov erlooked at necropsy. We review the gross and microscopic anatomy of the bu lbourethral glands in laboratory mice and report in SJL/J and RBF/DnJ mice a series of anomalies of this gland that appear to be common in these strai ns and relatively strain specific. From 14 different inbred strains of mice that had been submitted for necropsy over a period of 4.5 years for variou s clinical complaints, including enlargement of the perianal region, 23.8% of SJL/J mice (27/113) and 51.2% of RBF/DnJ mice (21/41) had cystic hyperpl asia of the bulbourethal glands. Furthermore 7.3% of BALB/cByJ mice (3/41) had cystic glands and 6.7% of DBA/2J mice (4/60) had enlarged bulbourethal glands, three of which (5.0%) were abscessed. All selected mice were active male breeders older than 6 months of age from production colonies at The J ackson Laboratory. Detailed examination of bulbourethral glands of retired SJL/J breeders revealed cystic glands in 83.8% (109/130) of mice. No abnorm alities were found in the other inbred strains of mice investigated.