28. Pathologic keratinizationregulation of epidermal cell differentiation •cytokines –e.g....
Transcript of 28. Pathologic keratinizationregulation of epidermal cell differentiation •cytokines –e.g....
28.
Pathologic keratinization
9th October 2019
Stratum lucidum (clear layer)
(Odland granules)
steps of keratinisation
• Cytoplasmic filaments
– praekeratin
• Keratohyalin granula
– autophagocytosis
– granula formation
• Odland’s granules
– granula bordered by membranes
regulation of epidermal cell
differentiation• cytokines
– e.g. growth factors, interleukins, TNF
• hormones– e.g. vit D3, cortisol
• nutritional factors– protein uptake, Zn, Cu, vit.s A and B
• autoregulation (autocrine function)
disturbances of keratinisation
• frequently in the cornified epithelium– skin
– modified appendices of the epithelium• hoof, horn …
– forestomachs
– esophagus (carnivores < su < eq < Ru)
– pars oesophagica• e.g. rat, horse
– mouth cavity• different sites according to the species
• back of the tongue
• also in non-cornified epithelium– but data are scarce
Disturbances in keratinisation
• 1) Hypokeratosis• rare
• wasting diseases
• starvation
• 2) Hyperkeratosis
• 3) Parakeratosis
• 4) Dyskeratosis• keratinisation in the str. spinosum
Disturbances in keratinisation
Forms
• Hyperkeratosis (2)– thickening of the str. corneum
– cornification process completed• (cell nucleus dissolved)
• Parakeratosis (3) – thickening of the str. corneum
– incomplete cornification process• (cell nucleus retained)
• Local (A) – generalized (B)
• Congenital - Aquired
• intense epithelial hyperplasia
• intense keratinisation
in the str. corneum
• cutaneous horn
2/A) Local hyperkeratosis
• mechanical cause
– callus, tyloma
• chronic inflammation or circulatory disturbance
– pachydermia
• malformation (hamartia)
– cutaneous horn (cornu cutaneum)
• trophoneurotic disturbance
– „hard pad” (chronic canine distemper)
2/A) Local hyperkeratosis
Hard pad disease
2/B) Generalized hyperkeratosis
• A-avitaminosis or anti vitamin A effect
– nutritive
• biotin-deficiency
– common in turkey
• toxical floor (asphalt)
– piglets
• intoxication - chlorinated naphthalenes
– cattle’s X-disease (1950’s)
• primary seborrhea
– cocker spaniel, WHWT, persian cat etc.
• ichthyosis congenita (disease group)
– recessive genetical (lethal) factor (cattle, dog)
• nutritive: vit. A deficiency
• toxicosis: chlorinated naphthalenes
Biotin deficiency
Ichthyosis congenita - calves
• complete orthokeratotic
hyperkeratosis
• more forms
• severe complications
Ichthyosis congenita - dogs
• complete orthokeratotic
hyperkeratosis
• more forms, few breeds
Hyperkeratosis in the rumen
3) Parakeratosis
• cornyfied layer thicker
• nuclei still present close
to the surface
– skin edema
– Zn-deficiency
• pigs/dogs skin
– chronic inflammation
• skin, rumen etc.
3) Parakeratosis
• macroscopic lesions
• SKIN– dry, laminar structure and crumbling
– Zn-deficiency• consistency: greasy (sebaceous gland hyperfunction)
• colour: dark brownish after drying out
– acanthosis nigricans/ AN-like disorders• consistency: dry, velvety touch
• colour: melanin hyperpigmentation
• RUMEN– papillae stick together → willow-leaf-like apperiance
– maceration → „greasy” consistence of cornified layer
3) Parakeratosis
• Lack of granules
• Retained nuclei of epithelial cells
in str. corneum
Hyper- and parakeratosis
• disturbance of the keratinisation of the rumen
epithelium (hyper- and parakeratosis) results in a
specific disease in cattle
hyper- and parakeratosis of the rumen
liver abscessation
hyper- and parakeratosis-rumenitis
liver abscess complex
hyper- and parakeratosis-rumenitis
liver abscess complex
hyper- and parakeratosis of the rumen,
liver abscessation
• constant (pathologic) acidic pH
• hyper- and parakeratosis - locus minoris resistentiae
• colonising pathogenic bacteria
• chronic inflammation
• bacteria in the propria - v. portae - liver
• purulent, ichorous and/or necrotising inflammation
Parakeratosis - liver abscessation
syndrome
4) Dyskeratosis
• keratinisation starts in the
str. spinosum
• prematured, apoptotic cells
• rare
• primary– congenital (polled Hereford calves)
• secondary