13. Endocrine System Flashcards
Endocrine features
Glandular epithelium (except for pp)
Richly vascularised
Controlled by +/- feedback loops
Posterior pituitary
Downgrowth of hypothalamus
Composes of neural tissue + supporting glial cells
= Swollen nerve terminals with dark red neuro-secretory granules
= ADH + oxytocin
Anterior pituitary
Epithelial cells in richly vascular fibrous stroma. Black rings of reticulin.
Not distinguishable:
Somatotropin’s
Autotrophs
Corticotrophs
Gonadotropins
Thyrotrophs
Somatotrophs (50%)
GH - found most laterally with diffuse +ve cytoplasm
Lactotrophs (25%)
Prolactin - brown polygonal cells with cytoplasmic process round other cells
Corticotrophs (15-20%)
ACTH - Near gland medial, round basophilic cells stain dark purple + large vacuoles
Gonadotrophs (10%)
FSH, LH - round/oval cells scattered
Thyrotrophs (1%)
TSH - angular chromosomes with elongated cytoplasmic process
Pineal gland
Irregular lobes of specialised neurone-like pinealocytes that secrete melatonin
= Central round nuclei, eosinophilia cytoplasm arranged in rosettes around a central capillary.
(Calcium accumulates with age)
Thyroid gland
Combination of follicular cells (single cuboidal) and colloid (produces thyroxine + calcitonin) with rich vascular supply
Parathyroid gland 3 cell types
Adipocytes
Chief cells - small polygonal with little cytoplasm secret PTH
Oxyphil cells - larger polygonal with abundant cytoplasm + fine granules
Paracrine gland
Islets of Langerhan = ball of endocrine cells surrounded by thin fibrous capsule.
B, A, D (somatostatin), PP (Pancreatic polypeptide) cells
Adrenal cortex
Zona glomerulosa - thin incomplete layer of small cells with vacillated cytoplasm secretes mineralcorticoids
Zona fasiculata - large polygonal cells with clear cytoplasm + abundant lipids secrete glucocorticoids
Zone reticularis - small polygonal cells secrete androgens
Adrenal medulla
Large polyhedral chromaffin cells (epinephrine -> adrenaline
Norepinephrine -> noradrenaline)
