Step 1: Understanding homologous glands.
Homologous organs are those which have the same embryonic origin but may perform different functions in males and females.
Step 2: Comparing male and female glands.
In females, the vestibular (Bartholin’s) glands secrete mucus to lubricate the vaginal opening. In males, Cowper’s (bulbourethral) glands secrete a lubricating fluid into the urethra.
Step 3: Conclusion.
Therefore, Cowper’s gland in males is homologous to the vestibular gland in females.