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Endocrine Histology

Pituitary

Identification:

Unmistakeable if the entire organ is visible in the field of view (low power), appearing as a misshapen, two-tones fruit, complete with stem. In some slides, the combination of red, whitish, and blue stained regions is also distinctive.

Features to know:

The anterior pituitary (1) is glandular and stained pink or red. The posterior pituitary (2) is composed of nervous tissue and mostly whitish and unstained. The posterior pituitary is contiguous with the infundibulum (3) that connects it to the hypothalamus of the brain.
  • Hormones produced at the Anterior Pituitary - ACTH, FSH, LH, GH, TSH, Prolactin, MSH
  • Hormones released at the Posterior Pituitary - ADH, Oxytocin
Photo of Pituitary Gland
Photo of Pituitary Gland

Thyroid

Identification:

The thyroid gland is the only slide you will see in which larger circular structures (follicles, 1) are filled with a uniformly pink staining substance, the colloid (2).

Features to know:

  • Each circular structure is called a thyroid follicle (1).
  • The pink substance within each follicle is the colloid (2), composed of the protein thyroglobulin.
  • Each follicle is surrounded by a layer of simple cuboidal epithelium (3).
  • In the spaces between the follicles are parafollicular or C-cells (4).

Hormones produced:

  • Follicles: thyroid hormones, T3 and T4
  • C-cells: calcitonin
Photo of Thyroid Gland
Photo of Thyroid Gland

Adrenal Gland

Identification:

Look for a multilayered effect, with several layers of different "textures" due to differing arrangements of cells. Lacks the tubular or circular structures seen in many of the other slides. At low power the gland may often (but not always) appear roughly triangular.

Features to know:

  • The irregular outermost layer of connective tissue is the capsule (1).
  • The next region deep to the capsule is the adrenal cortex (2-4), which itself is subdivided into 3 zones.
  • The first (outermost) zone of the cortex is the zona glomerulosa (2). It is fairly thin, and there are noticable spaces between the small clusters of cells.
  • Next is the zona fasiculata (3). It is the thickest layer and can be recognized by having cells arranged in distinct vertical columns.
  • The deepest zone of the cortex is the zona reticularis (4). Its cells are rather irregularly arranged.
  • The deepest portion of the adrenal gland is the adrenal medulla (5). There are usually noticable gaps between the cells.

Hormones produced:

  • Cortex - aldosterone, cortisol, androgens
  • Medulla - epinephrine and norepinephrine
Photo of Adrenal Gland
Photo of Adrenal Gland

Pancreas

Identification:

Extensive, small, dense clusters of cells with occasional larger clusters of lighter staining cells.

Features to know:

  • The islet of Langerhans (1) form distinctive clusters that stain lighter than the surrounding cells
  • The bulk of the cells in this photo are acini cells (2), which produce pancreatic juice used in digestion.
  • Also note the pancreatic duct (3).

Hormones produces:

  • Islets of Langerhans
  • alpha cell produce glucagon
  • beta cells produce insulin
Photo of Pancreas Gland