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Endocrine Glands

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Slide 1: Pituitary, saggital section, cat, H&E. Shows structural relationships of the anterior and posterior pituitary with the stalk and hypothalmus. The space in the anterior lobe between the pars distalis and pars intermedia represents a remnant of Rathke's pouch which would not be seen in a human pituitary. The space in the pars nervosa and infundibular stalk would also not appear in a human pituitary. Note the cellular nature of pars distalis, the fibrous appearance of pars nervosa, and the small follicles in the pars tuberalis (around top of infundibular stalk) and in the pars intermedia.  

Slide 2: Pars intermedia, human pituitary. Note the small follicular structures and the clusters of adenohypophysis-type cells.  

Slide 3: Low power of the pars intermedia between the adenohypophysis and nervosa, human, H&E.  

Slide 4: Posterior pituitary with Herring bodies (small, blue-grey, rounded hyaline-appearing structures), pituicytes and blood vessels, Mallory stain.  

Slide 5: Slightly light slide of the posterior pituitary with Herring bodies, Human, H&E. More difficult image than Slide 4.  

Slide 6: Posterior pituitary with Herring bodies, Dog, PAS-Fast green stain. Why are the Herring bodies PAS+? (Ans: Although the ADH and oxytocin are not glycosylated the neurophysins are).  

Slide 7: Pars distalis, human, H & E. Basophils and acidophils can be easily distinguished although basophils are more purple than blue. Several chromophobes are seen just above the center of the field. The space seen between the clusters of cells and surrounding connective tissue is artifact and in life is partially occupied by an abundant sinusoidal capillary network.  

Slide 8: Pars distalis, cat, Mallory stain. Acidophils and basophils are easy to distinguished although the image is somewhat dark. Chromophobes are scattered throughout the cell mass. They are most difficult to spot - look for nuclei surrounded by apparent space. Capillaries are of wide diameter and are called sinusoids. Here, because of their content of RBC's, they are quite evident.  

Slide 9: Pars distalis, dog, PAS & fast green stain. Acidophils are greenish blue. Basophils appear purple due to PAS staining of their glycoprotein secretory granule contents. Review which cells are PAS +.  

Slide 10: Pineal, human. The color of this slide has been altered from the original. The predominant cell type which should have a slightly basophilic cytoplasm is the parenchymal or chief cell (also called pinealocyte). Among them are interstitial cells with stellate shape and long cytoplasmic processes. Neither can be distinguished in this image. Contributing to the fibrous appearance are cell processes of neurons, mostly of the autonomic system. Concretions, such as those seen here, are typical of the human pineal gland.  

Slide 11: Thyroid gland lobes and cricoid cartilage, as well as muscles of the neck, low power.  

Slide 12: This slightly light image shows follicles with typical cuboidal epithelium and a light staining, uniform colloid. The rich blood supply is not evident.  

Slide 13: Thyroid gland, Mallory stain. This image demonstrates the extensive vascularity of the thyroid gland because many of the blood vessels are filled with red blood cells.  

Slide 14: Thyroid, PAS & hematoxylin. The glycoprotein thyroglobulin in the colloid stains red with PAS. The large pale cells seen against the bases of follicles are the parafollicular, clear, or "C" cells which produce calcitonin. Note that they appear to be within the basement membrane surrounding the follicle.  

Slide 15: Thyroid, rat, toluidine blue, 0.5 micron plastic embedded section. Palely stained parafolliclular or "C" cells are seen scattered along the bases of the follicles and very thin-walled capillaries (containing deeply stained red cells) indent the basal aspect of the follicular epithelium.  

Slide 16: Parathyroid, H & E. Note the dense cellular appearance and fat cells within the connective tissue. Since a parathyroid gland is often confused with a lymph node, note the lack of a capsule and subcapsular sinus, or the division of the organ into cortex and medulla (which you would see in a lymph node).  

Slide 17: Parathyroid, a higher magnification image of the previous slide, H&E. Oxyphil cells are not prominent. Note that chief cells appear small, dark and "lymphocyte-like".  

Slide 18: Parathyroid of an adult human, H&E. The amount of adipose tissue in the gland increases with age.  

Slide 19: Parathyroid, older human, H&E. Oxyphil cells, large with acidophilic cytoplasm, also increase with age. A cluster of them is seen in the center of the field. They are easily distinguished from the smaller chief cells. (See next image)  

Slide 20: Parathyroid, older human H&E. Oxyphils at higher magnification. Their nuclei are smaller and denser than those of the chief cells. Chief cell nuclei are more closely packed due to their smaller cell size. This gives the basophilic appearance to the parathyroid gland seen at low power. Chief cell cytoplasm, however, stains quite palely.  

Slide 21: Adrenal, H&E. The zones of the cortex are easily demarcated even at this low magnification and the medulla is clearly distinguishable.  

Slide 22: Adrenal, H&E, fixed with a fixative containing dichromates (chromaffin reaction). Medullary cells show brown coloration from the chromaffin reaction.  

Slide 23: Adrenal, H&E. Artery penetrating from capsule at left through the cortex toward the medulla at right. Locate the border between the cortex and medulla.  

Slide 24: Adrenal, H&E. From left to right: capsule, zona glomerulosa, zona fasiculata. Note that the fasiculata cells appear lighter (due to their higher content of lipid droplets).  

Slide 25: Adrenal, monkey, H&E, plastic embedded section. Opposite orientation as previous slide, i.e., capsule to the right. Note the capillaries between the clumps and cords of zona glomerulosa cells.  

Slide 26: Adrenal, monkey, H&E, plastic embedded section. Lipid droplets in the zona fasiculata cells are extracted during tissue preparation. Note the position of the sinusoidal capillaries between the cords of cells.  

Slide 27: Adrenal, guinea pig, TEM. A zona fasiculata cell showing extracted lipid droplets, fairly abundant mitochondria with lamellar and tubular cristae, and smooth endoplasmic reticulum (ser).  

Slide 28: Adrenal, guinea pig, TEM. Deep zona fasiculata cell with larger but less numerous lipid droplets and more abundant SER. Mitochondria are pleomorphic.  

Slide 29: Zona reticularis cells are arranged in anastomosing cords on left. More basophilic medullary cells are clustured at right.  

Slide 30: Adrenal medulla, Loris, toluidine blue-acid fuchsin stain of plastic embedded tissue. The cytoplasm of the cells has catecholamine-containing granules.  

Slide 31: Adrenal, guinea pig, TEM, Adrenal medullary cell. Epinephrine containing granules are larger with more palely staining granular content. Norepinephrine granules have a more condensed granule content.  

Slide 32: Adrenal medulla, guinea pig. TEM  

Slide 33: Low power image of a pancreas. Several, different sized, lighter staining islets are seen among the aciner elements and ducts.  

Slide 34: Pancreas (fixed by perfusion), Monkey, toluidine blue-acid fuchsin stain, low power. See the next image for a higher magnfication view.  

Slide 35: Pancreas (fixed by perfusion), Monkey, toluidine blue-acid fuchsin stain, higher magnification. The blood vessels are dilated and empty (washed out during the perfusion). Note the great vascularity of the islet of Langerhans.  

Slide 36: Pancreas, Halmi stain. Islet of Langerhans in an unperfused, paraffin embedded preparation. The cells are pale in contrast to the very deeply stained exocrine pancreatic acinar cells. Beta cells are stained blue to purple by this stain. Unstained alpha cells are seen mainly at the periphery of the islet.  

Slide 37: Two adjacent sections of pancreas containing an islet which has been immunostained for glucagon on the left and insulin on the right. Note the relative locations of beta and alpha cells (alpha more peripheral).  

Slide 38: Pancreas, similar prep to slide 37 but not adjacent sections of the same islets. The islets have been immunostained for glucagon (left), insulin (center, most abundant) and somatostatin (right, least abundant).

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