Structure, function, diagnostics and therapy Flashcards by Sarah Long

Which cells in the skin originate from the neural crest?

Melanocytes

How well did you know this?

Not at all

Perfectly

Which are the first hairs to appear on a foetus?

Vibrissae and tactile or sinus hairs

How well did you know this?

Not at all

Perfectly

Gene W causes which coat phenotype?

White (pink skin, blue or brown eyes and white hair) - also called albino

All non-white horses are ww

How well did you know this?

Not at all

Perfectly

Gene G causes which coat phenotype?

Exclusion of pigment from hair - greying. GG or Gg horses always have pigment in their skin and eyes.

All non-greys are gg.

How well did you know this?

Not at all

Perfectly

Gene B causes which coat phenotype?

Black hairs on the points and /or most of the body, the b allele allows black hair in the skin but not the hair (e.g. chestnuts).

How well did you know this?

Not at all

Perfectly

Gene A causes which coat phenotype?

The distribution of black hairs e.g. A and B is the bay colour.

How well did you know this?

Not at all

Perfectly

Gene C causes which coat phenotype?

Pigment dilution. Fully pigmented horses are CC, heterozygotes are e.g. palomino and cc are cream with pink skin and blue eyes.

How well did you know this?

Not at all

Perfectly

Gene D causes which coat phenotype?

Dun patterning

How well did you know this?

Not at all

Perfectly

Gene To causes which coat phenotype?

Tobiano spotting

How well did you know this?

Not at all

Perfectly

In general, how many cell layers thick is the epidermis in horses?

5 to 7 cell layers

How well did you know this?

Not at all

Perfectly

Which body sites show rete ridges in haired skin?

Mane and tail bases

How well did you know this?

Not at all

Perfectly

The below proteins make up which epidermal structure?
BPAG1/BP 230
Plectin
alpha-6-beta-4 intergrin
BPAG2/BPAG180/collagen XVII
Laminin 5

Hemidesmosomes

How well did you know this?

Not at all

Perfectly

Which special stains can be used to identify melanocytes on histopathology?

DOPA reaction

Fontana ammoniacal silver nitrate

How well did you know this?

Not at all

Perfectly

Which type of melanin contains a high proportion of sulphur?

Phaemelanins

How well did you know this?

Not at all

Perfectly

Dopaquinone is the key intermediate in the metabolic pathway for which substance?

Melanin

How well did you know this?

Not at all

Perfectly

Which copper-containing enzyme is the rate limiting enzyme for melanogenesis?

Tyrosinase

How well did you know this?

Not at all

Perfectly

Melanosomes originate from which organelle?

Golgi apparatus

How well did you know this?

Not at all

Perfectly

Which epidermal cells have high-affinity receptors for Fc-IgG and complement 3, contain membrane associated vimentin, adenosine triphosphatase, CD45, S-100 protein and CD1 and are aurophilic?

Langerhans cells

How well did you know this?

Not at all

Perfectly

What is the epidermal turnover time in horses?

~17 days

How well did you know this?

Not at all

Perfectly

What effect does inflammation have on skin pH?

Switch from acidic or neutral to alkaline

How well did you know this?

Not at all

Perfectly

How thick is the BMZ in haired skin in horses?
1.5-5um
8-15um
25-35um

1.5-5um

How well did you know this?

Not at all

Perfectly

Collagen accounts for what % of dermal fibres?

90%

How well did you know this?

Not at all

Perfectly

Match the fibres and the stains used to differentiate them:
Collagen
Reticulin
Elastin

Verhoeff and van Gieson stains
Special silver stains
Masson trichrome

Collagen - Masson Trichrome
Reticulin - Special silver stains
Elastin - Verhoeff and van Gieson

The unusual cross-linking of desmosine and isodesmosine gives which dermal fibre it’s remarkable strength?

Elastin

Match the collagen types and their location: Type IV Type V Type VII Anchoring fibrils Lamina lucida Lamina densa

Type IV - Lamina densa Type V - Lamina lucida Type VII - Anchoring fibrils

Which stain highlights mast cell granules on histopathology?

Toludine blue | AOG (Acid‐Orcein Giemsa)

True or False: In horses, a single hair arises from each follicle and is accompanied by sebaceous and epitrichial sweat glands and an arrector pili muscle.

True

The inner root sheath keratinises and disintegrates when it reaches which level of the hair follicle?

The isthmus

Where is the outer root sheath thickest, towards the epidermis or the hair bulb?

Towards the epidermis

Arector pili muscles play a role in thermoregulation and emptying of which glands?

Sebaceous glands

Which proteins are up-regulated on endothelial cells during inflammation?

ICAM-1 (intercellular adhesion molecule) | VCAM-1 (vascular cell adhesion molecule)

Name three breeds of horse predisposed to atopic dermatitis

``` Quarter Horse Thoroughbred Warmblood Arabian Morgan ```

Name three breeds of horse predisposed to insect bite hypersensitivity

``` Icelandic Friesian Quarter Horse Warmblood Shire Shetland Connemara ```

Which two species of Demodex mites can be found on horses?

Demodex equi | Demodex caballi

Which topical antiseptic can destroy fluorescence in cases of dermatophytosis?

Iodine

Which dermatophyte, commonly isolated from horses, does not grow on DTM?

Trichophyton verrucosum

Reticular degeneration is most commonly seen with which acute/subacute inflammatory dermatoses?

Dermatophilosis | Acute contact dermatitis

Hydropic degeneration of basal epidermal cells is usually associated with which diseases?

Cutaneous adverse drug reactions Lupus erythematosus Erythema multiforme Vasculopathies

Cholesterol clefts on histopathology (clear spaces in needle or spicule shape) are seen with which diseases?

Xanthomatosis Panniculitis Ruptured follicular cysts

Define desmoplasia

Fibroplasia induced by a neoplastic process

Villi (dermal papillae projecting into a vesicle or bulla) are seen with which diseases?

Photosensitisation Bullous pemphigoid Epidermolysis bullosa Cutaneous adverse drug reactions

Name two diseases that can show diffuse mucinosis

Hypothyroidism | Lupus erythematosus

Which special stain aids visualisation of the BMZ?

PAS

``` Multinucleated epidermal giant cells are typically associated with which types of infection? Bacterial Protozoal Fungal Viral ```

Viral infectionss

``` Which histopathological reaction pattern is typically caused by: Hypersensitivity Ectoparasites Dermatophytosis Dermatophilosis Seborrheic disorders Contact dermatitis ```

Superficial and deep perivascular dermatitis

Name two diseases that cause diffuse parakeratotic hyperkeratosis with perivascular dermatitis

``` Ectoparasites Dermatophilosis Dermatophytosis Malassezia dermatitis Zinc-responsive dermatitis Hepatocutaneous syndrome ```

Chymase, tryptase and dipeptidly peptidase II are enzyme histochemical markers of which inflammatory cell?

Mast cell

True or false? | The skin's permeability to drugs increases as the hydration of the stratum corneum increases

True

True or false? | Astringents precipitate proteins and generally do not penetrate deeply

True

Name two types of occlusive emollients?

Vegetable oils Animal oils (eg. lanolin, lard) Hydrocarbons (e.g. paraffin, petrolatum) Waxes

How do hygroscopic agents work?

They are moisturisers that are incorporated into the stratum corneum and attract water.

Give two examples of a hygroscopic agent

``` Propylene glycol Glycerin Colloidal oatmeal Urea Sodium lactate Carboxylic acid Lactic acid ```

What dilution of chlorhexidine is non-irritant and suitable for wound irrigation?

0.05%

Below which concentration is urea a humectant and not keratolytic?

20%

What are the well known adverse effects of DMSO?

Garlic-like odour Increased warmth and/or pruritus (histamine release, exothermic with water) Dehydration (too hygroscopic)

Zinc oxide and titanium dioxide are examples of which type of sunscreen, physical or chemical?

Physical; they form an opaque barrier

Horses show highest blood cortisol concentrations at which time of day?

In the morning - oral steroids should be given at this time