46. , pseudometaplasia Regeneration

• resorption, remotion, replacement • perfect regeneration restitutio ad integrum (regeneratio)

• imperfect regeneration restitutio cum defectu

REPARATION Direct forms of repair

– Hypotypia • original cells, but not the original structure – Heteromorphosis • instead of original cells other (not connective tissue) type of cells – Hyperregeneration, hypermorphosis • fill the area, but continue proliferation – Repair • Organisation, Demarcation Indirect forms of repair

• Accomodation (adaptation) after irrevocable, permanent dysfunction – – (increase in size) – (increase in number) – Metaplasia (change in the tissue type) – Transformation • certain changes in internal architecture Metaplasia

• special case of defective healing – one type of differentiated tissue is replaced by another type of differentiated tissue • limited possibility of changing • only two types of tissue – epithelial tissue to epithelial tissue – connective tissue to connective tissue

• NO OTHER POSSIBILITIES! Forms of metaplasia

• direct metaplasia (occurrence not proved yet) – differentiated cells undergo transformation • indirect metaplasia – multipotens cells replace the degenerated tissue – differentiate in a different way (columnar epithelium  simple epithelium = basal cell metaplasia) – (more differentiated) – (less differentiated) Cartilagenous and osseous metaplasia (*) of the dura matter of the spinal cord Causes of metaplasia

• every kind of , but… • ...presence of certain conditions – vitamin A deficiency in poultry – irritation of the mucosal membranes by external factors or chronic – F-2 toxins in the uterus – bone tissue formation in a wound (ovariectomy, chronic hernia, haematoma) – ossification of the left atrium

Metaplasia of laryngeal respiratory epithelium

The chronic irritation has led to an exchanging of one type of epithelium (the normal respiratory epithelium at the right) for more resilient squamous epithelium (left). Metaplasia of esophageal squamous mucosa to gastric type columnar mucosa at the left – Barrett’s oesophagus (human)

Epithelial metaplasia

Cervix: columnar to cuboidal Epithelial metaplasia

Later squamous epithelium Epithelial metaplasia Epithelial metaplasia

Oesophageal glands glandular to squamous epithelium Mesenchymal metaplasia (abdominal hernia) Mesenchymal metaplasia (abdominal hernia) Mesenchymal metaplasia Pseudometaplasia

• appearences mimicking metaplasia • different kind of tissue in a certain place • originating from choristia – tonsils  cartilage – gastric mucosal tissue  oesophagus islets –  kidney tissue – spinal cord  some portions of intestines – simple epithelium of vagina  columnar ep. Allomorphia, dismorphia

• change in shape, but not in type • reversible • Example: – thyroid gland • epithelial cells lining the follicules – lung • epithelial cells lining the alveoles

Degenerative changes

47. Atrophy Atrophy

• Decrease of the size of an organ or cell by reduction in cell size and/or reduction in cell numbers

Related terms

• • Failure of normal development of an organ: developmental anomaly

• Involution • „Physiological atrophy” – response to the decreased requirement of the body for the function of a particular cell or organ

Unilateral kidney hypoplasia, cat Muscular hypoplasia, pig Forms of atrophy

• Physiological - pathological • Simple – degenerative • Reversible – irreversible • Regional – complete • Numeric atrophy Involution (physiological atrophy)

• Embryo or fetus – Müllerian/Wolffian duct system • Neonate – Ductus arteriosus • Early adult – • Adult female – Cyclic changes in the endometrium • Old age – Endometrium, testicles, bone, cerebrum etc. Pathological atrophy

• Decreased function – „disuse” – Muscle atrophy in fractured limbs • Loss of innervation – Injury, inflammation, tumors of nerves etc.

Paralysis of the n. radialis, horse

Poliomyelitis, man Muscular atrophy, myositis eosinophilica, dog Pathological atrophy

• Pressure atrophy – External • „Bed sores” – Internal • Tumors • Parasites • CSF-accumulation

Cysticercus cysts, brain, monkey Cysticercus tenuicollis cyst, liver, pig Atrophy of the cerebral cortex and cerebellar hypoplasia, calf

Urolithiasis in the kidney calyces, cattle Pathological atrophy

• Lack of nutrient supply – Cachexia • Blood supply distrubances – Thrombosis • Disturbances of endocrine stimulation – Skin atrophy in Cushing’s • Atrophy due to drug application – Topical steroids

Cachexia, bone marrow, cattle Diagnostic hints

• Consider the age of the animal • More sharp edges of organs, darker muscle, harder to tear parencymatous organs • Size of an organ is not decreased – The atrophied tissue is replaced by another (e. q. connective or fatty) tissue • muscular pseudohypertrophy Muscular pseudohypertrophy, horse; cattle 48. Accommodation

• counteracting of the harmful effects • in case: – when the tissue loss is too big – healing was organization or heteromorphosis • Hypertrophy • Transformation – certain changes in internal architecture – adaptation to changed load conditions • bone, blood vessels Hypertrophy

• increase in size  increase in activity • without significant structural changes – hypertrophia in sensu strictori • simple enlargement – hypertrophia numerica (hyperplasia) • associated with cell multiplication • differentiation between hypertrophy & hyperplasia is almost impossible Idiopathic Adrenal Cortical Hyperplasia Epithelial hyperplasia associated with chronic inflammatory conditions

Staphylococcus "neonatal hyperkeratosis"

Bacterial conjunctivitis in a turtle Chr. inflam. of intestinal mucosa Preconditions

• increased output only in healthy organs • requires good nutrient & oxygen supply • good innervation & general state • tissue type (muscle, certain glandular organs) • Manifestation – enlarged organs (shape normal) – thickening of the wall (in hollow organs) • simple hypertrophy (hypertrophia concentrica) • dilation of the lumen (hypertrophia excentrica) Types of hypertrophy

• Physiological – uterus during pregnancy (muscles) – mammary gland during lactation – skeletal & heart muscle during training • Pathological – increased work load – compensatory (vicarious) – correlation type 1. H. due to increased work load • valve defects in the heart • narrowed orifices – heart – urinary bladder (enlarged prostate) – intestines ( or innervation problem) – oesophagus (cardiac sphincter spasm) – bronchi (verminous bronchitis) Pressure overload

2. Compensatory hypertrophy • in paired organs one replaces the other’s lost function – kidney • glomerules enlarge, tubules proliferate – testes • not seen in ovaries – adrenal gland – liver • partial hypertrophy, partial hyperplasia

3. Correlation type hypertrophy

• enlargement & hyperfunction of endocrine glands – metabolic disorder stimulates • hypocalcemia or phosphate retention causes hypertrophy in the parathyroid gland – activity of the synergistic gland – missing inhibiting effect of antagonistic gland • leads to hormonal dysfunction Endocrine-origin hypertrophy/plasia

Functional tumor of the pituitary gland (chromophobe adenoma) which secretes ACTH. ACTH stimulates the adrenal cortex to synthesize and release steroids. Pseudohypertrophy • enlargement, but not increased function

• muscle – pseudohypertrophia lipomatosa musculorum – enlargement of muscles in case of muscular atrophy – replacement by fat tissue • liver - connective tissue proliferation in chronic inflammation • skin & mucous membranes – polyps, elephantiasis following chronic inflammation • - by hyperregeneration (caro luxurians) • teeth - overgrowth due to inactivity • hormonal dysfunction (pituitary, ovaries, testicles) • developmental anomalies

Transformation of the tissues (transformatio)

• Vessels – Collaterales • Bones – Different directions – Weight – Etc.

• Tendons Transformation of the tissues Transformation of the tissues (transformatio)