Lecture 2: Integument I Flashcards
What are the layers of the epidermis from most superficial to deep
Corneum, lucidum, granulosum, spinosum, basale
The lucidum is only present where
In thick/ hairless skin (ex: paw pads)
What specialized cells are in the epidermis
Melanocytes, langerhans, merkel cells
What is the dermis composed of
Collagen, elastic fibers, GAG matrix, vessels, nerves, piloerector muscles
Adnexa: hair follicles, sebaceous glands, apocrine glands, eccrine glands
What is the adnexa composed of
Hair follicles, sebaceous glands, apocrine glands, eccrine glands
What is the subcutis/panniculus/hypodermis composed of
Adipose tissue, collagenous, elastic fibers, more vessels and nerves
Identify 1-3
- Epidermis
- Dermis
- Subcutis/panniculus/ hypodermis
What layer of the skin is made of mature keratinocytes (corneocytes), toughness of skin/protection layer
Stratum corneum
What layer of the skin is composed of polyhedral cells without granules attached by desmosomes, when fixed appear “spines”
Stratum spinosum
What layer of the skin are desmosomes most apparent
Stratum spinosum
What layer of the skin is only present in hairless skin, composed of compact keratinized cells and appear transparent histologically
Stratum lucidum
What layer of the skin is the germinal layer, cuboidal cells, rest on basement membrane, and have unipotent stem cells
Stratum basale
What layer of the skin is composed of the granular cell layer, granules of keratin (keratohyalin granules)
Stratum granulosum
What cells of the epidermis protect the skin from the environment. They arise from stratum basale and differentiate as they reach stratum corneum
Keratinocytes
What is the function of melanocytes
Melanin pigment, color to hair follicle and skin, protect from UV injury
What is the function of langerhans
Type of dendritic cell that presents antigens to T cells
What is the function of merkel cells
Mechanoreceptors, present in skin with high tactile sensitivty
Based on the appearance of skin layers which image is more likely to be taken from the thorax vs paw pad and why
Left: thorax because much thinner epidermis
Right: paw pads because thicker epidermis and stratum corneum
What is indicated by the circle
follicular Ostia (pore)
What are some functions of the dermis
- Tensile strength and elasticity
- Vascular supply, nerves and movement of immune cells
What layer of skin is responsible for wound healing and sensation
Dermis
What is the function of hair follicles
Protection/ thermal insulation, sensory perception
What are the 4 stages in the hair growth cycle
- Anagen
- Catagen
- Telogen
- Exogen
What affects the hair growth cycle
Nutrition, health status, hormones, season
What are the 3 regions of the hair follicle
- Infundibulum
- Isthmus
- Inferior region
What is the infundibulum of the hair follicle
Part of the hair follicle extends from the epidermis to the opening of the sebaceous gland duct
What is the isthmus of the hair follicle
Extends from the attachment of the arrector pili muscle into the entrance of the sebaceous gland duct
What is the inferior region of the hair follicle
Includes the hair bulb, growth, nutrients, and anchors
What is the function of the arrector pili muscle
smooth muscle contraction, causes erection of hairs and expression of sebaceous glands
What type of gland is the sebaceous gland
Holocene gland- cells contain fat and when cells breakdown contents/secretions are released
What are the functions of the sebaceous gland
Secrete sebum onto skin surfaces and into follicles to protect hair follicle and lubricate
What is this and what adnexal structure could have caused this
feline chin acne- caused by sebaceous gland—> folliculitis and comedon formation
What are apocrine glands
Sweat glands, “coiled glands: of hair skin, secrete at level of follicular Ostia
What are eccrine glands
Sweat glands “tubular glands” typically of non-haired skin, secrete onto epidermal surface
What are some locations for eccrine glands
- Paw pads
- Frog
- Nasolabial region
What are some functions of the subcutis/panniculus
- Structural support and anchor to deeper tissues
- Collagenous and elastic fibers: flexibility
- Adipose tissue: flexibility, tissue insulation, shock absorption, caloric reserve
What are some portals of entry to the dermis
- Hematogenous
- Nerves
- Penetration via follicular Ostia
- Rupture of sebaceous gland, apocrine gland or follicle
What is the portal of entry/ spread for erysipelothrix rhusiopathie, TMS cutaneous reactions
Hematogenous
What is the portal of entry and spread for FHV-1
Nerves
What is the portal of entry/ spread that is utilized by mites, bacteria, dermatophytes
penetration via follicular Ostia
What is this and what is likely cause and portal of entry
Ulcerative facial dermatitis
Cause: FHV-1
POE: nerves
What is this, what is the cause and what is portal of entry
Diamond skin disease
Cause: E. Rhusiopathie
POE: Hematogenous
What is hyperkeratosis
Alterations in cornification, increased thickness of stratum corneum
What are the two types of hyperkeratosis
- Orthokeratosis
- Parakeratosis
Orthokeratosis vs parakeratosis: which has nuclei present vs absent
Orthokeratosis: nuclei absent
Parakeratosis: nuclei present
What are some primary and secondary causes of orthokeratosis
Primary: seborrhea in cocker spaniels
Secondary: ichthyosis, callus
What are some causes of Parakeratosis
Zinc responsive dermatitis, superficial necrolytic dermatitis
What is wrong
Orthokeratosis
What is wrong
Parakeratosis
What is hyperplasia
Increase in number of cells
Hyperplasia is typically secondary to ___
Chronic stimuli
What are the 4 types of hyperplasia
- Regular
- Irregular
- Papillated
4, pseudocarcinomatous
What is dysplasia
Abnormal development, alteration in size, shape, and organization of mature cells
T or F: dysplasia precedes formation of non-invasive carcinomas
True
What metabolic disease is atrophy common in
Cushing/ hyperadrenocorticism
What is spongiosis
Fluid accumulation between cells
Spongiosis is secondary to __ or ___
Trauma or acute inflammation
What is hydropic or ballooning degeneration
Intracellular fluid causing cytoplasmic swelling of keratinocytes that can lead to rupture an formation of microvesicles
What are some causes of hydropic/ ballooning degneration
Immune mediated dz
1. Lupus erythematosus
2. Dermatomyositis
3. Lupoid onychodystrophy
What wrong
Spongiosis
What wrong
Hydropic degneration
What is acantholysis
Disruption of intercellular junction (desmosomes) between keratinocytes
What are some examples of dz that can cause acantholysis
- Pemphigus vulgaris
- Pemphigus foliaceus
What is a vesicle/bullae
Fluid filed intraepidermal or subdermal space
What causes vesicles/ bulllae to form
immune mediated, burns, viral etc that lead to lack of epidermal cell adhesion—> fluid accumulation
What wrong
Spongiosis
what wrong
Acantholysis and pemphigus follicaceous
What is hyperpigmentation/ what cause
Increased melanocytes or increased melanin production
What causes hyperpigmentation/ what is pathogenesis
Chronic inflammation—> increased melanin stimulating factor
What wrong
Hyperpigmentation, ex: lentigo in cats
What is the congenital or hereditary cause of hypopigmentation
Lack of melanocytes, failure to make melanin, failure of melanin transfer
What are some examples of acquired hypopigmentation
- Copper deficiency
- Uveodermatologic syndrome
- Pigmentary incontinence
What is pigmentary incontienence
Inflammation vs immune mediated causes melanin to move from the basal epidermal layer to the dermis
What is the result of atrophy in the dermis
Decreased collagen fibers, fibroblasts, adnexa, decreased thickness and elasticity
What are some examples of dz that can cause atrophy in dermis
1 Cushing
2. Skin fragility syndrome in felines
What occurs during fibrosis in dermis
Proliferation of fibroblasts and newly formed collagen fibrils
T or F: collagen dysplasia is inherited
True
What is the result of collagen dysplasia
Decreased tensile strength—>increased stretch of skin
What is an example of a disease that cause collagen dysplasia
Ehlers danlos
What wrong
ehlers danlos- collagen dysplasia
What is the correct orientation of granulation tissue
Vertically oriented capillaries and horizontally oriented fibroblasts and a few collagen fibers providing a “lattice work”
What type of tissue is this based on orientation
granulation tissue
What wrong and what disease is commonly associated
Calcinosis cutis
Dz: Cushing
What occurs during acute dermatitis
Hyperemia, edema, exocytosis of leukocytes, release of inflammatory mediators
What are the 4 results of acute dermatitis
- Resolution
- Abscess
- Scar
- Progression
What cells are present in chronic dermatitis
Macrophages, lymphocytes, and p,as a cells
What type of hypertrophy is commonly associated with acral lick dermatitis
Follicular hypertrophy
What is follicular dysplasia
Failure of hair growth due to abnormal development of follicle and/or hair shaft
T or F: follicular dysplasia is inherited
True
What is folliculitis
inflammation of hair follicle
What is perifolliculitis
Inflammation around hair follicle
What is mural folliculitis
Inflammation in the wall of the hair follicle
What is luminal folliculitis
Inflammation in the lumen of the hair follicle
What is furunculosis
Inflammation weakens the follicular wall and results in rupture and release of contents into dermis
What are some causes of furnuculosis
Dermatophytes, mites, bacteria
What’s going on here
Left: alopecia and hyperpigmentation
Left middle: mite on follicular lumen—> mural folliculitis
Right middle: mural folliculitis, vacuolar degeneration
Right: follicular wall disrupted- furnuclosis
What is hidradentitis
Inflammation of apocrine gland
What is sebaceous adentitis
Inflammation of sebaceous gland
What type of disease is sebaceous adentitis
Immune mediated
What does histo of acute sebaceous adenitis look like
Lymphocytes and macrophages around ducts
What does chronic sebaceous adenitis look like
Loss of sebaceous glands, scarring, follicular hyperkeratosis
What breeds have a genetic predisposition to sebaceous adenitis
Poodles and Akitas
What is the diagnostic test for sebaceous adenitis
Skin biopsies
What wrong
sebaceous adenitis
What is panniculitis
Inflammation of adipose tissue/subcutis
What is the main target of primary panniculitis
Adipose tissue
What is an example of primary panniculitis and its pathogenesis
Feline pancreatitis—> decrease vitamin E in diet—> oxidation of fat—> pyogranulomatous inflammation
What is secondary panniculitis
Subcutis is affected by inflammation of dermis that extends into subcutis
What are some causes of secondary panniculitis
- Deep bacterial folliculitis with furunculosis
- Penetrating wound
- FB
