Pituitary Gland Pathology Flashcards
What are the secretory products of the pituitary gland? (10)
Pars distalis = endocrine in response to hypothalamic secretions
- Somatotrophs - STH (GH)
- Luteotrophs - prolactin (LTH)
- Gonadotrophs - LH, FSH
- Thyrotrophs - TTH
- Corticotrophs - ACTH, beta-endorphin, MSH (alpha, beta)
Pars nervosa = neuroendocrine:
- Oxytocin
- Arginine vasopressin
Three parts of the adenohypophysis (3)
- Pars distalis
- Pars tuberalis
- Pars intermedia
What is the neurohypophysis composed of?
Pars nervosa - represents distal component of neurohypophyseal system
Function of adenohypophysis - PARS DISTALIS and cells types it is composed of (6)
- Pars distalis produces, stores & releases trophic hormones in response to hypothalamic secretions.
Composed of the following cell types:
- Corticotrophs - secrete ACTH, results in increased secretion of cortisol.
- Somatotrophs - secrete somatotrophin (growth hormone).
- Lactotrophs - secrete prolactin
- Gonadotrophs - secrete luteinising hormone (LH) & follicle-stimulating hormone (FSH)
These cell types are morphologically subdivided into acidophils, basophils, and chromophobes based on the staining of their secretory granules. Granules stain histologically with slightly different tinges of pink – it’s easier to tell them apart with immunohistochemistry.
Function of adenohypophysis - PARS INTERMEDIA and cells types it is composed of (7)
- Pars intermedia surrounds the residual Rathke’s pouch.
- Composed of melanotrophs - secrete proopiomelanocortin (POMC).
- Melanotrophs are inhibited by dopamine released from the hypothalamus.
- POMC is cleaved into adenocorticotrophic hormone (ACTH). This is “clinically insignificant” because it is rapidly cleaved into:
- Melanocyte-stimulating hormone (MSH)
- β-endorphin
- Corticotrophin-like intermediate peptide (CLIP)
Neurohypophysis - pars nervosa hormones (3)
- Pars nervosa compromised of axonal projections from hypothalamic neurones, stores hormones produced by hypothalamus:
- Oxytocin
- Antidiuretic hormone
How does the adenohypophysis get bigger? (3)
What are the mechanisms of endocrine disease and give some examples (4)
What are the three main things that happen to the adenohypophysis? (3)
- Gets bigger
- Gets smaller
- Gets inflamed
Physiologic hyperplasia of adenohypophysis (3)
- Stimulation through the hypothalamic-pituitary-target organ axis
- Tends to target trophic hormone-producing cells of interest
- If there’s a need or it is frequently used (constant stimulation), the body will power it up
- Pituitary gland doesn’t become grossly enlarged but target organ may become enlarged
Pathological hyperplasia of adenohypophysis (4)
What are neoplasias of the adenohypophysis usually?
Adenomas (benign epithelial tumour, glandular origin), carcinomas very rare, pituitary gland tumour must metastise
What are the adenomas of the adenohypophysis and what do they cause? (2)
What are the ways in which the adenohypophysis gets smaller? (7)
Physiological atrophy of adenohypophysis (3)
Iatrogenic atrophy of adenohypophysis (2)
Causes of degeneration/necrosis of adenohypophysis (4)
Causes of hypophysitis (3)
What is diabetes insipidus and the two types? (4)
- Osmolality of urine in these cases is less than or equal to plasma even with water deprivation
- PUPD
Equine pituitary pars intermedia dysfunction
What is pituitary pas intermedia dysfunction (PPID)?
What is PPID due to?
Clinical signs of PPID (4)
Foetus produced due to disruption of foetal endocrine function from veratrum californicum consumption by ewe
Ruminants - adenohypophysealaplasia and prolonged gestation (6)
Causes of adenohypophysealaplasia and prolonged gestation in ruminants and what does it result in? (2)
- Aplasia of the adenohypophysis = genetic disease in Guernsey & Jersey
- Toxins can also mess up hypothalamic function, disrupting the hypothalamic-pituitary-adrenal axis e.g., ingesting veratrum califoricum
- Defective hypothalamus results in subnormal development of the adrenal cortices
- Cyclopia & CNS malformations in lambs
What are craniopharyngeal duct cysts? (4)
What are Rathke’s cleft cysts? (4)
Cause panhypopituitarism and pituitary dwarfism
What is pituitary dwarfism? (4)
What is hypersomatotrophism (Feline acromegaly)? and what are the clinical signs? (9)
What are the causes of hypersomatotropism (feline acromegaly)? (8)
Tend to be middle-aged males cats with no apparent breed disposition
What are the clinical signs of hypersomatotropism (feline acromegaly)? (8)
