NoVC01answered grow question 7mo ago Pollen sacs start to develop during the late-vegetative stage. Once a male marijuana plant reaches maturity, which typically happens around 4 to 5 weeks into the flowering stage, the pollen sacs burst open and release pollen into the air.
It's possible for regular seeds to produce nothing but females. My F3 seeds have only produced females in three grows, F1/F2 produced males but not F3.
Google: "marijuana male stage of growth" for more detailed information.