Final answer:
The male organ that enlarges after age 40 and causes increased urinary frequency is the prostate gland.
Step-by-step explanation:
The male organ that enlarges after age 40 and can cause increased urinary frequency is the prostate gland.
During puberty, the prostate gland normally doubles in size, and around age 25, it gradually begins to enlarge again. This enlargement is called benign prostatic hyperplasia (BPH), and it can cause the prostate to press against the urethra, leading to urinary symptoms such as frequent urination. By age 60, about 40 percent of men have some degree of BPH, and by age 80, the number jumps to as many as 80 percent.
Treatments for BPH aim to relieve the pressure on the urethra, including medication for mild to moderate symptoms and surgery to remove a portion of the prostate tissue for severe enlargement.