Lecture 9: Histology of Hoof

Question 1

perissodactyl

Answer 1

odd-toed (horses)

Question 2

artiodactyl

Answer 2

even-toed
- cattle, sheep, goat, pig

Question 3

specialization of skin that results from the cornification of the entire integument at the distal end of the digit

Answer 3

hoof

Question 4

hoof capsule is _____

Answer 4

epidermis (germinative, proliferative, keratinized layers)

Question 5

corium is ______

Answer 5

dermis (innervated + vascularized)

Question 6

what layer of the hoof capsule is fully keratinized

Answer 6

S. corneum

Question 7

what layer of hoof is only partially keratinized

Answer 7

S. granulosum

Question 8

what layer of hoof contains stem cells

Answer 8

S. basale

Question 9

what layer of hoof contains proliferative cells

Answer 9

S. spinosum

Question 10

what is the periople

Answer 10

zone of transition from skin to hoof

Question 11

the unions of the hoof wall with the base of the frog are the ______

Answer 11

bulbs

Question 12

identify the numbers

Answer 12

2 = wall
2c = bars
3 = sole
4 = frog

Question 13

identify 2a and 2b

Answer 13

2a = perioplic groove
2b = coronary groove

Question 14

what are 3 and 4

Answer 14

3 = sole
4 = frog

Question 15

how many layers is the corium?

Answer 15

just ONE, single layer w/ different zones

Question 16

what are the zones of the wall corium

Answer 16

• perioplic c.
• coronary c.
• laminar c.

Question 17

what strata layers make up the hoof wall?

Answer 17

• s. externum
• outer s. medium
• inner s. medium
• stratum internum

Question 18

what layer of hoof wall is the area of overlapping b/w the corium and hoof capsule

Answer 18

Stratum internum

Question 19

what wall stratum are associated with the different corium zones

Answer 19

Perioplic corium
- stratum externum

coronary corium
- outer stratum medium
- inner stratum medium

laminar corium
- stratum internum

Question 20

identify 1, 2, 4, 7

Answer 20

1 = periople
2 = perioplic corium
4 = coronary corium
7 = laminar corium

Question 21

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

Answer 21

perioplic corium

Question 22

the stem cells associated w/ the coronary corium generate cells that will form….

Answer 22

the inner and outer stratum

Question 23

the stem cells associated with the ____ corium are quiescent

Answer 23

laminar

Question 24

The perioplic, coronary, sole and frog corium all belong to what larger corium type

Answer 24

papillary, therefore associated w/ hoof regions responsible for wall growth

Question 25

The perioplic, coronary, sole and frog corium all provide ____ to stem cells

Answer 25

support, nutrients, oxygen

Question 26

the germinative layer of the hoof capsule is synonymous to what stratum layer

Answer 26

basale

Question 27

the stratum basale at the papillae region produces the _____ hoof

Answer 27

tubular

Question 28

the stratum basale at the inter-papillary regions produces the ____ hoof

Answer 28

inter-tubular

Question 29

keratinization of the tubular and inter-tubular hoof occurs where

Answer 29

below the papillae

Question 30

what does Rhodamine (red compound) stain

Answer 30

keratinizied tissue

Question 31

a _____ area exists b/w the stem cells and keratinized cells

Answer 31

non-keratinized area

Question 32

the stem cells on the papilla and inter-papillary region are equivalent to what in skin

Answer 32

stratum basale

Question 33

what strata contain Rhomadine-negative cells

Answer 33

S. spinosum and S. granulosum

Question 34

what strata contain Rhomadine-positive cells

Answer 34

S. corneum

Question 35

how is the stratum internum of the wall formed

Answer 35

interlocking of epidermal and dermal lamellae

Question 36

purpose of stratum internum

Answer 36

- create the suspensory apparatus for the 3rd phalanx and its associated structures makes attachment of capsule and corium efficient

Question 37

The laminar corium attaches to the periosteum of the ______ and to the perichondrium of the ______

Answer 37

periosteum of the 3rd phalanx and the perichondrium of the lateral cartilages

Question 38

purpose of secondary lamellae

Answer 38

increase SA for attachment

Question 39

how are the stem cells (s. basale) located on the surface of the secondary dermal lamellae different than those of the papillary corium

Answer 39

these stem cells normally don't differentiate; they are quiescent unless needed to heal wounds at wall

Question 40

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

Answer 40

bulbs

Question 41

what is the zona alba

Answer 41

the union of the wall and sole that is poorly pigmented

Question 42

at the zona alba, the papillary corium (terminal papillae) replaces what

Answer 42

papillary corium replaces the laminar corium and produces the full keratinization of the stratum internum

Question 43

the stem cells of the papillary corium (terminal papillae) generate new hoof between ?

Answer 43

new hoof b/w epidermal lamellae

Question 44

what are the lamellar remodeling enzymes involved in hoof growth

Answer 44

- Matrix metalloproteinases (MMP I+II) : digest laminin and collagen - Tissue inhibitors of metalloproteinase : inhibit MMPs

Question 45

explain how hoof growth occurs

Answer 45

1. 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 2. 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

Question 46

the tubular horn works as a specialized '________"

Answer 46

"column"

Question 47

What are the hoof strategies to avoid 'column' rupture

Answer 47

- 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

Question 48

what structural differences are seen in the artiodactyl hoof

Answer 48

- no frog, but has extensive digital pad - no bars - reduced sole - wall extends distally - no secondary lamellae

Question 49

identify 2,3,4

Answer 49

2 = wall 3 = sole 4 = digital pad

Question 50

in artiodactyl hooves, the corium of the digital pad is equivalent to that of the ____

Answer 50

frog in perissodactyl

Question 51

1?

Answer 51

1 = epidermal lamellae

Question 52

in an artiodactyl hoof, the corium of the digital pad is continuous w/ the one of the ____

Answer 52

sole. there is no clear distinction b/w the two