The human body is similar for both sexes. However, there are areas that are obviously different and not so obviously different. In regards to bicycles and their seats, these differences contribute quite significantly to the design of bicycles and their accessories.
For example, as young boys grow older into puberty, their facial structure changes. Some of these changes include a heavier jawline, a larger nose and a more prominent brow. For designers, this means that men’s helmets and glasses will need to be bigger and longer to accommodate the larger head mass.
Similar differences are in play when we look at hips. The male and female hips are different in size and this has been a factor in bike seat designs. According to Wikipedia, the female pelvis is different from that of males in order to facilitate child birth.
So female riders would tend to be more comfortable using a wider back seat to support the extra fat around their buttocks while the seat nose would be shorter in length.
This means that bicycle seats for men would normally be narrower and longer than the normal female version. Of course, there are exceptions to this rule with varying sizes of men. But the rule is normally the same. The wider the buttocks, the wider the seat rear and shorter the nose. Most bike seats nowadays would also have center relief cut into the seats.
With studies done both recently and previously, there has been confirmed cases issues amongst males in regards to their reproductive organs. A recent survey has concluded that at least 5 percent of male rider may get dysfunctional problems because of poor cycling techniques coupled with pressure on the perineum. The perineum is the area of the groin that sits directly on the bicycle seat nose. Both men and females may get some numbing feeling as they get off their bikes.
To combat this issue, some manufacturers have cut off the nose area of the seat and so the seat is just composed of the back and rear ends. The cyclists using these seats have to stop sliding off the back and rear type seat by exerting more pressure on the hand lebars and pedals.