Antler seals are the ends of the cast antlers where they have separated from the pedicles.
4 antler seals. The youngest animal on the right decreasing seal to the left
In the young animal the separation leaves a concave surface on the top of the pedicle which heals over as the blastema.
Skull from DVC You should have seen the car.
Blastema is the start of the velvet growth for that season's antlers. As the animal ages with each antler cycle so the top of the pedicle flattens and in old age becomes convex. Ageing of antler architecture leads to the loss of the tines initially and eventually the beam becomes smaller finally ending up as mere "blobs " at the end of the pedicles
The initial explanation for senescence ( Ageing of animals - greying etc,in old animals head lower thinner neck ) was lower testosterone levels in old age. This has now been proved to be incorrect. The testosterone receptors in the velvet are less responsive although confusingly most of antler growth prior to calcification is under the influence of oestrogens.
Even more bizarre muntjac will sometimes cast antlers through the pedicle at an angle.