In Summary : Testosterone blood level drops the skin around the coronet swells about 7 days before casting of antlers. The coronet, join between the pedicle and the antlers weakens and the antlers are cast. Antlers firmly attached can be cast 1/2 hour later. Once cast the blastema immediately starts healing with the special skin ' velvet ' and the antlers for the following season start growing. No English name for the developing antler so use the term ' panty ' from Slav and Russian terms. There is a Chinese term.
Velvet so called because hair grows at right angles to the surface.it is also a source of sebum and pheromones so very greasy to touch. When I touched the velvet and subsequently went to a tame hind she exhibited a Flehmen response ( This is a drawing up of the top lip to, we believe intensified scent to the vomeronasal organ ) She thought i was very nice ? It has a very good blood supply. These blood vessels have a different construction to the other blood vessels of the body.
As these blood vessels grow they produce a substance Neurotropin 3 which facilitates nerve grow. These connect to the axon ( roughly body of nerve cell ) in the brain. Thus the connection made between nerve tissue and the antler ( target organ). Thus giving form to the antler for that year This is important as the antler growth is phenomenally fast and grows from the tip and also the cicumference. Lesser blood supply up the 'core' of the antlers. Initially believed blocked when velvet removed but persists for ' life of antler and recent research indicates it strengthens the antler for the clashes during the rut . When the antlers are calcified due to high levels of testosterone ( last third of growth ) the blood vessels constrict and fatty blobs deposited until they block and velvet dies.
Velvet has the most numerous nerve supply in the body. These are purely sensory and are derived from the V th cranial nerve ( trigeminal ). Deer are very conscious of their antlers (panty) when they are in velvet. This is how they know the position of antler tip when scratching themselves. Any fight at this time they box or flail with their front legs, similar to hinds
An imminent research scientist and deer hunter has advanced a theory there is an antler growth centre in the brain which holds information for conformation of antler growth over the life of the deer. Shape number of tines etc sequentially for each year of life.
Experimental work demonstrates this nerve supply is essential for the conformation of antler growth. When antlerogenic tissue was transplanted to various positions on the body small rudimentary antlers grew following the normal antler cycle
The basic shape of the antlers is genetically controlled but various factors can alter this. The most usual is damage either to the velvet or nerve. The earlier the damage the greater the abnormality..
If velvet damaged on one side the other keeps growing so deviation to the damaged side whilst it repairs itself . Hence examples of drooping tines. If early 'panty' is affected there are different responses. If at right angles to the pedicle splitting of the antlers. Different response in Roe and Reds. In Roe the brow tine does not develop where as in Reds it does. If the damage is across the 'panty'' there is a complete replica of the antler on that side.
If the pedicle is fractured and separates it repairs itself . If portion split away a rudimentary straight antler will grow on the smaller portion. The maximum amount of damage seem to occur when the outside (lateral) of the 'panty' is involved.
In addition velvet produces sebum which gives rise to pheromones which drift downwind for other animals to pickup. When thrashing fraying as velvet shed transferred to objects trees etc. These pheromones are also transferred to antlers by those deer which piddle on them and also wallow.
Going back to antler growth centre in the brain. Information about antlers seems to be stored there to be repeated annually if damage occurred.
All this abnormal antler development is down to sensory perception. If the animal feels it there can be an effect. Greater pain greater reaction . If nerves are blocked by anaesthetic as in velvet harvesting ( illegal in UK ) no effect in subsequent years.
Damage to legs. If a front leg is damaged,fractured or lost the antler on that side can be affected leading to variation of the normal architecture. Healing blood vessels produce Neurotropin 3 and the antler growth centre remembers this. So variation repeated annually.
If a hind leg injured the same way the opposite antler affected Contralateral.
If the injury severe enough both antlers affected.
Castration of a Sika on one side was followed by deformity on the opposite side antler ( contralateral ).
There are cases on record of antlers developing style of an entirely different species. Cause unknown. This suggests the genetic potential to develop antlers characteristic of other species is latent in the genes of all deer.
Seal ( end of cast antlers nearest pedicle ) If convex animal improving. Concave animal going back.
This doesn't apply to Munctjac. They are tropical deer and the seals are always the same. When casting antlers the testosterone levels don't drop as low as other deer so always fertile. Also they cast irregularly They also remain in velvet longer as calcification takes longer.
Roe does ------pedicle formation quite common. antler development less so. Can be hermaphrodite, pseudohermaphrodite. Adrenal gland tumours, cystic ovaries : produce androgens ( testosterone like hormones ). Damage to skin over pedicleat opportune time when prolactin high enhances action of androgens ( see part one )
Hummel ( Scots term ) Not stag in West Country.
Believed due to delayed puberty. They are fertile.
Experimentally operated on pedicle 2 out of 3 developed antlers.
Knobler : Roe Buck which hasn't developed antlers but intact.
Perugue------ most common in Roe, lack of testosterone so stay in velvet which grows like cancer but doesn't spread throughout body.
Murder buck/ switch ---- without tines to antlers due to damage to 'panty' See splitting of 'panty ' previously.
Genetics is difficult subject as can't keep sufficient number of deer to make statistical significant observations. Hence based on observations on generations over many years.