Practicals Flashcards
Histopath, anatomy, clinical exam, case examples
What is a key feature of endocrine cells?
Large cytoplasms to allow for the production of the hormones
Describe the histopathological appearance of the adenohypophysis, the neurohypophysis and the pars intermedia relative to each other
- Neurohypophysis is paler than the other two portions of the pituitary gland
- Pars intermedia is blue
- Adenohypophysis is dark purple
What is the typical trend in hormone production as a neoplasm grows?
The more malignant a neoplasm gets, the less of the hormone is usually found - more focus on multiplying than producing hormone
Describe the appearance of chromophobes in the pituitary gland
Appear grey
Give an example of chromophobic cells
Melanotropes, produce MSH
What is secreted by acidophils/eosinophils and describe their appearance
- Secrete growth hormones
- Pink
Give examples of basophils, what they produce, and describe their appearance
- Somatotropes: GH
- Gonadotropes: FSH, LH
- Lactotropes: PRL
- Thyrotropes: TSH
- Corticotropes: ACTH
- Blue appearance
What is a potential consequence of a growing pituitary tumour regarding the rest of the brain?
- May grow upwards and destroy brain tissue above it
- INcrease in intracranial pressure
- May get destruction of thalamus, hypothalamus and ventricular system, leading to other conditions such as neurogenic diabetes insipidus
Describe the appearance of the adrenal glands and thyroid glands in the case of a pituitary tumour leading to adrenocortical hypofunction?
- Both will be atrophied
- In adrenal gland will clearly see brown medulla and white cortex (white due to fat and cholesterol)
Describe the appearance of the adrenal glands in the case of a functional pituitary adenoma
Massive laminar hypertrophy and hyperplasia in adrenal glands
Compare the appearance of the endocrine and neuroedocrine cells of the adrenal gland
- Endocrine cells: adrenal cortex, eosinophilic, close pattern
- Neuroendocrine cells: more basophilic, paler, nuclear pattern more open
What is produced by the neuroendocrine portion of the adrenal gland?
Catecholamines
What features may be seen in an adrenocortical carcinoma?
- Difficult to identify cells as normal adrenal cortical cells
- Tumour cell emboli in the vasculature
- Nuclear, cellular and cytoplasmic pleomorphism visible
What histopathological features may be seen in a pheochromocytoma?
- Neoplastic chromaffin cells haphazardly arranged in poorly demarcated lobules of varied sizes
- Moderate variation in cellular and nuclear size and shape
- If malignant, will be dark red brown, if cortical will be white
Describe the appearance of normal, hyperactive and underactive follicular cells of the thyroid gland
- Normal: cuboidal
- Overactive: elongated
- Underactive: flattened
Describe the appearance of the thyroid follicles in over and underactive thyroid glands
- Over: collapsed follicles, lumens of remaining contain pale pink colloid and have numerous endocytic vacuoles at the epithelial cell-follicular lumen interface
- Under: follicular lumens distended with dense colloid
Explain the prognosis for a malignant endocrine tumour
- Poor
- Endocrine glands have close association with blood vessels, so metastases develop quickly
Describe the normal appearance of cells in the pancreatic islets
Pale cytoplasm
Describe the appearance of islet amyloid
- Pink, dense islets
- Irregular shape
- Amorphous pink material in cells = amylin
Explain how islet amyloid deposition occurs
- Islet amyloid polypeptide (IAAP, amylin) is normal secretory product of beta-cells
- Over production of abnormal amylin (beta-pleated sheet conformation abnormal) by beta cells leads to deposition in cells as it cannot be broken down, cells degenerate = loss of function of cells
what is the function of islet amyloid polypeptide
- Regulatory peptide
- Functions locally in islets by inhibiting insulin and glucagon secretion
- And also at distant targets
Describe the sympathetic supply for the adrenal medulla (nerve, origin, pre-/post-ganglionic)
- Mainy greater splanchnic nerves
- These originate from sympathetic trunk
- Are pre-ganglionic, adrenal cells act as the post-ganglionic cells
Compare the histological appearance of adrenal glands and lymph nodes
- In medulla of lymph nodes, will find germinal follicles due to immune responses
- These will not be found in the adrenals
Describe the pattern of venous drainage of the pancreas
- Body and neck drain into splenic vein
- Head drains into the superior mesenteric and portal veins into the liver
- Some branches communicate with the superior mesenteric vein directly, creating loop of venous drainage utilising both sets of venous plexi
Name the structures that sit in the following locations relative to the pituitary gland:
- Rostrally
- Caudally
- Ventrally
- Laterally
- Dorsal
- Rostrally: optic chiasma
- Caudally: mammillary bodies
- Ventrally: sphenoid bone
- Laterally: cavernous sinus
- Dorsal: hypothalamus
Describe the embryological origin of the pituitary gland
- Adeno: upgrwoth of roof of developing mouth, called Rathke’s pouch, ectoderm
- Neuro: down-growth from ectoderm of forebrain (diencephalon/future hypothalamus)
What is produced by the epiphysis? What is it’s function?
Melatonin, function is circadian rhythm, and control of seasonal breeding
What brain region does the epiphysis belong to?
The telencephalon
In which animals, are the right and left thyroid glands connected by a functional isthmus?
Pigs, humans, cattle
What anatomical factors should be taken into consideration when performing a thyroidectomy?
- May be some ectopic tissue so may not remove all thyroid cells
- 3rd parathyroid located near/next to or on thyroid gland but should be left in place
- Care re. surrounding musculature, blood vessels, trachea, oesophagus
- 4th parathyroids usually within the thyroid gland so will be removed in a thyroidectomy
What aspects need to be addressed in every general examination of a horse?
- Assess horse in natural environment where possible, assess gait, breathing, demeanour etc.
- Assess environment pasture (presence of plants, stocking density, fencing, faeces), individual and other stables
- Other horses
- Physical examination, incl. BCS
Describe the general physical examination of the head and neck a horse
- Contours of head and neck
- Normal position and carriage
- MMs, drooling, dropping feed
- Nasal discharge, assess character of any discharge, airflow from nostrils
- Percuss maxillary and frontal sinus area
- Assess eyes for symmetry and free of discharge, characterise discharge, erythema, cloudiness, swelling, blepharospasm etc. Palpebral response, menace response
- Facial artery
- Ears - symmetry
- Palpation of LNs
- Neck from both sides, jugular vein
Describe the general physical examination of the thorax of a horse
- Auscultate heart, assess rate, rhythm, murmurs
- Auscultate lung fields, check for adventitious sounds
- Check for evidence of pectoral oedema
Describe the general physical examination of the abdomen of a horse
- Auscultate for abdominal borborygmi in 4 quadrants
- Evaluate distension in paralumbar fossa if applicable
- Check for oedema, commonly in sheath area or at most dependent portion of the abdomen
Describe the general physical examination of the perineum and genital region of a horse
- Check the rectal temperature, simultaneously check anal tone
- Check for evidence of diarrhoea
- F: Examine vulva and udder for swelling discharge, heat or pain on palpation
- M: examine prepuce, sheath, testes for swelling, discharge, heat, pain on palpation
- Check normal tail carriage and movement
Describe the general physical examination of the limbs of a horse
- Assess symmetry, even weight bearing on all feet, heat, pain, lameness, raised digital pulses or swelling
- Lift feet and examine
Describe the general physical examination of the skin of a horse
- Examine for hair loss, scabs, papules, nodules , seborrhea
- Evidence of ectoparasites
- Scratching/rubbing, abnormal swelling, abnormal sweating
