Embryologically, the prostate, seminal vesicles, and ductus (vas) deferens originate from 2 separate structures. The prostate arises from a budding collection of tissue in the urogenital sinus. The seminal vesicles and the ductus deferens are formed from the mesonephric duct.
The prostate develops from epithelial outgrowths form the prostatic segment of the urethra that grows into the surrounding mesenchyme. This outgrowth and branching start at week 10 during embryo growth; by week 12, there are 5 groups of tubules that form the lobes of the prostate. The first group makes up the middle lobe; the second and third groups make up the right and left lateral lobes; the fourth group is the posterior lobe that starts from the floor of the urethra; and the fifth group is the anterior lobe.
The following image depicts the posterior view of the prostate gland.
Prostate gland, posterior view.