Classical endocrine glands and classical disease categories
Classical endocrine glands and BETTER (i.e., more appropriate) disease categories.
Positive and negative feedback systems are the principles of of the endocrine system and there effects upon each other and target organs.
Generally, “releasing” hormones are between the hypothalamus and adenohypophysis, and “stimulating” hormones are between the pituitary and other major endocrine glands. Build up of a and hormone tells the hypothalamus and pituitary to “slow down” production. It is important to understand the difference between POSITIVE and NEGATIVE feedback.
Anterior pituitary lobe = adenohypophysis = Rathke’s pouch = pars distalis. Hormones released here are also made here. Posterior pituitary lobe = neurohypophysis = infundibulum = pars nervosa. Hormones released here are made in the hypothalamus.
Overall cellular mechanisms of action of the two major classes of hormones, polypeptide and steroid.
All three lobes of the pituitary: Anterior, intermediate, and posterior lobes. Note that the pituitary also has a “portal” circulation, i.e., artery capillaries veins capillaries, rather than just a c v. Why? Ans: to create a “secondary” circulation between the pituitary and the hypothalamis releasing factors!
The differentiation between acidophils and basophils is usually not too difficult unless the stain is really lousy. Chromophobes are uncommon, and have minimal cytoplasm and no granules. Chromophobe cytoplasm stains close to basophil cytoplasm in color, but is less granular and has is a minimal cytoplasm.
Hormones from basophils go to other endocrine glands, thyroid, adrenal cortex, ovary, testis. Cells from acidophils do NOT.
The posterior pituitary (aka, pars nervosa or neurohypophysis) looks like typical brain tissue. Why? Ans: It IS typical brain tissue. The pituicytes are glial cells. Herring bodies are massively dilated terminal axons from the hypothalamus.
The posterior pituitary does not make these hormones, it just releases them. The hypothalamus actually makes the hormones and transfers it down the stalk to the neurohypophysis.
Note the extreme proximity of the pituitary stalk (infundibulum) to the optic chiasm
Galactorrhea in a young woman (non pregnant of course) is often the expression of an acidophil tumor of the adenohypophysis.
Recognize this famous pituitary giant? What kind of cells of the pituitary might be proliferating here? (acidophil or basophil)
What kind of cells of the pituitary might be proliferating here? (acidophil or basophil)
What kind of cells of the pituitary might be proliferating here? (acidophil or basophil)
Normal pituitary.
Find the pituitary adenoma.
Usually the bitemporal hemianopsia is NOT perfectly symmeetrical. Why? Because tumors are under no law to grow perfectly symmetrically.
The usual differential of hypopituitarism
Recall the basic thyroid blood supply, from subclavian (inferior posterior) and carotid (superior anterior)
The normal weight of the thyroid , in grams, is also the same as its 24 hour radioactive iodine uptake percentage. Why? Ans: Because it take up 1% per gram.
Find the colloid, follicular cells, and para-follicular cells (also known as C cells or light cells)
If there was such a thing as a hypothalamic adenoma producing excessive TRF (thyroid releasing factor), would this be tertiary hyperthyroidism? Ans: Yes. Would an adenoma or a carcinoma more likely produce hyperthyroidism? Ans: Adenoma Why?
The diagnosis of Hashimoto thyroiditis requires not only lymphoid follicles in the thyroid, but SECONDARY (i.e., germinal centers) follicles should be present.
NO scalloping
Scalloping
Podiatric case of the week.
Decreased Iodine leads to decreased thyroid hormone, which leads to increased TSH which leads to increased growth of follicles. That’s how an iodine deficiency leads to a goiter.
Many vegetables are goiterogens, fruits are NOT.
Most goiters worldwide are due to iodine deficiency. Why? Ans: The thyroid enlarges to try to trap more iodine, when serum levels are low. This is a adaptive response.
Every type of thyroid disorder known is more common in females than males? Why? Ans: unknown What is the difference between a cold and a not-cold nodule isotopically?
Did you ever know anybody who died from thyroid cancer? Why not?
EXTREMELY well encapsulated tumor. Benign.
EXTREMELY well encapsulated tumor. Benign.
Note the resemblance of H ü rthle cells to oncocytes, oxyphil cells, gastric parietal cells and apocrine cells, i.e., very bright red and abundant cytoplasm. In general however, please remember that “ATYPIA” in benign endocrine neoplasms is VERY COMMON, and, in contrast with other organ systems of the body, ususlly does NOT imply malignancy or PRE-malignancy!
EXTREMELY NON well encapsulated tumor. Malignant. Thyroid tissue can look perfectly normal, but come out of bone or liver? In contrast with marked atypia seen in BENIGN endocrine neoplasms, often NO ATYPIA is seen with malignant endocrine neoplasms, and invasion or metastases is often the only evidence that endocrine tissue is malignant.
Papillary neoplasms do NOT usually look uniform on cut surface.
To make things simple, let’s just say you can regard ALL papillary thyroid neoplasms as benign.
Orphan Annie cells are papillary carcinoma of the thyroid cells in which considerably cytoplasm has invaginated into the nucleus.
Is amyloid a type of “Hyaline”? What are some other types? What is hyaline?
This is just a generality, not a law.
Find the chief cells, find the oxyphil cells, find the fat.
PTH stimulates osteoclasts to chew up bone and transfer calcium from the bone to the serum “compartments”.
Hyperparathyroidism symptoms are the same as hypercalcemia symptoms, and vice versa.
Hypoparathyroidism symptoms are the same as hypocalcemia symptoms, and vice versa.
Is this a right or a left adrenal gland? Ans: LEFT Why: Right is usually flatter and much less triangular. Think of the liver as squishing it.
Congenital adrenal hyperplasia is generally synonymous with adrenogenital syndrome.
Note that the COLOR and CONSISTENCY of the tumor is the same as that of the CORTEX.
Note that the COLOR and CONSISTENCY of the tumor is the same as that of the CORTEX.
Note that the COLOR and CONSISTENCY of the tumor is the same as that of the MEDULLA.
MEN-1 is the three “P”s
Madullary thyroid carcinoma is present in ALL three types of MEN-2
Younger looking cells “BLASTomas” are primarilly in kids, more mature looking cells CYTomas are in adults. BOTH are quite rare.
4 hormones of the islets: glucagon, insulin, somatostatin. and pancreatic polypeptide from alpha, beta, delta, and PP cells, respectively. Can you tell from routine H&E microscopy which cell is which? Why not? Can immunoperoxidase help?
Even though there are TWO types of diabetes the complications from both are identical, although, of course, the effects of type-1 may have been present longer in a persons life.
Hyalinization in the islets of Langerhans is a common finding in type 2 diabetes. Often, the “hyaline” is amyloid.
In “nodular” glomerulosclerosis, aka, K-W kidneys, “nodules” of PAS positive matrix trapping mesangial cells, are found at the periphery of glomeruli.
Diffuse mesangial sclerosis. Note the “sclerotic” part, or fibrosis, is stained blue by the trichrome stain.
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