Lecture 9: Histology of Hoof Flashcards
perissodactyl
odd-toed (horses)
artiodactyl
even-toed
- cattle, sheep, goat, pig
specialization of skin that results from the cornification of the entire integument at the distal end of the digit
hoof
hoof capsule is _____
epidermis (germinative, proliferative, keratinized layers)
corium is ______
dermis (innervated + vascularized)
what layer of the hoof capsule is fully keratinized
S. corneum
what layer of hoof is only partially keratinized
S. granulosum
what layer of hoof contains stem cells
S. basale
what layer of hoof contains proliferative cells
S. spinosum
what is the periople
zone of transition from skin to hoof
the unions of the hoof wall with the base of the frog are the ______
bulbs
identify the numbers
2 = wall
2c = bars
3 = sole
4 = frog
identify 2a and 2b
2a = perioplic groove
2b = coronary groove
what are 3 and 4
3 = sole
4 = frog
how many layers is the corium?
just ONE, single layer w/ different zones
what are the zones of the wall corium
- perioplic c.
- coronary c.
- laminar c.
what strata layers make up the hoof wall?
- s. externum
- outer s. medium
- inner s. medium
- stratum internum
what layer of hoof wall is the area of overlapping b/w the corium and hoof capsule
Stratum internum
what wall stratum are associated with the different corium zones
Perioplic corium
- stratum externum
coronary corium
- outer stratum medium
- inner stratum medium
laminar corium
- stratum internum
identify 1, 2, 4, 7
1 = periople
2 = perioplic corium
4 = coronary corium
7 = laminar corium
The ______ corium is associated with the stem cells that give rise to the proliferative cells, which eventually get keratinized and constitute the stratum externum of the wall
perioplic corium
the stem cells associated w/ the coronary corium generate cells that will form….
the inner and outer stratum
the stem cells associated with the ____ corium are quiescent
laminar
The perioplic, coronary, sole and frog corium all belong to what larger corium type
papillary, therefore associated w/ hoof regions responsible for wall growth
The perioplic, coronary, sole and frog corium all provide ____ to stem cells
support, nutrients, oxygen
the germinative layer of the hoof capsule is synonymous to what stratum layer
basale
the stratum basale at the papillae region produces the _____ hoof
tubular
the stratum basale at the inter-papillary regions produces the ____ hoof
inter-tubular
keratinization of the tubular and inter-tubular hoof occurs where
below the papillae
what does Rhodamine (red compound) stain
keratinizied tissue
a _____ area exists b/w the stem cells and keratinized cells
non-keratinized area
the stem cells on the papilla and inter-papillary region are equivalent to what in skin
stratum basale
what strata contain Rhomadine-negative cells
S. spinosum and S. granulosum
what strata contain Rhomadine-positive cells
S. corneum
how is the stratum internum of the wall formed
interlocking of epidermal and dermal lamellae
purpose of stratum internum
- create the suspensory apparatus for the 3rd phalanx and its associated structures
makes attachment of capsule and corium efficient
The laminar corium attaches to the periosteum of the ______ and to the perichondrium of the ______
periosteum of the 3rd phalanx and the perichondrium of the lateral cartilages
purpose of secondary lamellae
increase SA for attachment
how are the stem cells (s. basale) located on the surface of the secondary dermal lamellae different than those of the papillary corium
these stem cells normally don’t differentiate; they are quiescent unless needed to heal wounds at wall
in the sole and frog, the corium attaches to the solar surface of the 3rd phalanx, except at the ______, where it attaches to the digital cushion
bulbs
what is the zona alba
the union of the wall and sole that is poorly pigmented
at the zona alba, the papillary corium (terminal papillae) replaces what
papillary corium replaces the laminar corium and produces the full keratinization of the stratum internum
the stem cells of the papillary corium (terminal papillae) generate new hoof between ?
new hoof b/w epidermal lamellae
what are the lamellar remodeling enzymes involved in hoof growth
- Matrix metalloproteinases (MMP I+II) : digest laminin and collagen
- Tissue inhibitors of metalloproteinase : inhibit MMPs
explain how hoof growth occurs
- non-keratinized cells from the papillary corium push down keratinized cells of the hoof capsule
— this creates a pressure area that induces the expression of matrix metalloproteinases
— they detach the epidermal and dermal lamellae
- keratninized cells slide down on the s. basale fo the secondary lamellae
– once pressure goes away, the union of the lamellae takes place again by secreting metalloproteinase inhibitors
the tubular horn works as a specialized ‘________”
“column”
What are the hoof strategies to avoid ‘column’ rupture
- inter-tubular horns reduce fragility by embedding tubular horn
- central cavity + concentric layers provide flexibility to tubular horn
- frog provides complementary support
- sole-frog angles open to cushion weight load
what structural differences are seen in the artiodactyl hoof
- no frog, but has extensive digital pad
- no bars
- reduced sole
- wall extends distally
- no secondary lamellae
identify 2,3,4
2 = wall
3 = sole
4 = digital pad
in artiodactyl hooves, the corium of the digital pad is equivalent to that of the ____
frog in perissodactyl
1?
1 = epidermal lamellae
in an artiodactyl hoof, the corium of the digital pad is continuous w/ the one of the ____
sole. there is no clear distinction b/w the two
