I've noticed that for some men the glans is really flared in the back, so it looks like a split, while for others the glans is not flared at all, and it doesn't look like there's a split.
I've noticed that for some men the glans is really flared in the back, so it looks like two a split of two big tubes, while for others the glans is not flared at all, and it doesn't look like there's a split.
I don't follow your description, with the reference to "a split of two big tubes." The only way I associate "flared" with the penis head is that the rim of the head flares out prominently on some penises, so that the rim is rather thick--that is, there's quite a "drop" to the shaft. On some the rim is sharp and may be rough, and on some it's smooth and rounded. Some heads may not have much of a flare to the rim at all, and it may rise only a bit from the rest of the shaft. Just natural variety, no reason for the differences.
If that's not what you're asking about, you'll have to clarify your question --or maybe somebody else will understand what you mean...
Thanks for answering. I edited my post since my initial description was unclear.
Ok, so it's a variety thing. Is it possible that the glans may develop and elaborate more after the age of fifteen?
I suppose you mean could the rim/flare become more prominent. Well, it depends on how developed the person's genitals are at that age. Some guys are still in a fairly early or mid-stage at 15, while others are almost fully mature, and their penis is the shape it's gonna remain. For someone who's still growing and developing, there could be some change, but not likely a whole lot, as far as the shape of the head is concerned. That's pretty much determined at (or before!) birth.... The shape of the head in this respect doesn't affect sexual sensations, of course.
P.S. After replying to your question, I now think that in referring to the "back" of the head you were probably thinking of the underside of the tip, in which case I can see what you meant by a "split." My answer still applies in principle, either way.