The micrographs that appear on this review page are typical views of the tissues seen in the laboratory. The descriptions that accompany them are designed to help you recognize each tissue and their features. The features for which you are responsible are bold faced. The hormones, that each tissue produces, are in blue text and link directly to a web page that reviews the gland secretions and their effects. An additional site is available dealing with disorders associated with abnormal hormonal secretions. The tissues included at this site for your review are:

HYPOPHYSIS

PANCREAS

PINEAL

THYROID

ADRENAL

OVARY

PARATHYROID

THYMUS

TESTIS

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HYPOPHYSIS - PITUITARY


At 40x the pars distalis (A) and the pars intermedia (B) of the adenohypophysis (anterior pituitary) and the pars nervosa (C) of the neurohypophysis (posterior pituitary) can be observed. The pars tuberalis and infundibulum were not a part of our preparation. The pars distalis secretes Growth Hormone (GH), Thyroid-stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), Follicle-stimulating hormone (FSH), Lutenizing hormone (LH),and Prolactin. The pars intermedia secretes Melanocyte-stimulating hormone (MSH). The pars nervosa stores ADH and Oxytocin which were secreted by the hypothalamus.

Scroll down this page to observe the pars distalis and the pars nervosa at a higher magnification.

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ADENOHYPOPHYSIS - PARS DISTALIS

At higher magnifications the dark staining chromophils ( A) and the very light staining chromophobes (B) are easily distinguished.

NEUROHYPOTHYSIS - PARS NERVOSA

This region of the pituitary is non secretory. Its cells are neuroglial-like pituicytes (C).

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THYROID

The thyroid gland is composed of many spherical hollow sacs called thyroid follicles. In this tissue section, each follicle (A) appears as an irregular circle of cells. The principal cells, which surround the follicle are simple cuboidal epithelium. These follicles are filled with a colloid (B), which usually stains pink. The principal cells use the thyroglobulin and iodide stored in the colloid to produce the primary thyroid hormones - including thyroxine.

Between these follicles are the parafollicular cells (C) which produce calcitonin.

 

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PARATHYROID GLAND







Because the parathyroids (A) are embedded in the thyroid tissue, their tissues are often found with the thyroid tissue. The chief cells that make up this gland are smaller and darker staining than those of the thyroid. At higher magnifications, we could see that the chief cells appeared in "ribbons" or "cords." These cells secrete parathyroid hormone (PTH) Recall that you are only responsible for recognizing this tissue when it appears with the thyroid gland.

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PANCREAS





The dark staining cells of the pancreas are exocrine and arranged in acini (sac like glands with ducts). These cells produce enzymes for the digestive system. At all magnifications lighter staining patches of cells, the pancreatic islets or islets of Langerhans (A), are visible. While the three types of cells that make up the islets can not be distinguished in our preparations, it is important to know that the alpha cells produce glucogon, and the beta cells produce insulin. (additional micrograph at higher magnification)

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ADRENAL GLAND


When observed at low magnification (left) the capsule (A), cortex (B), and medulla (C) are visible. At higher magnifications (right) the divisions of the cortex are visible: the zona glomerulosa - zg -with cells in small clusters which secrete aldosterone, the zona fasciculata - zf - with cells arranged in columns or strips which secrete cortisol and the zona reticularis - zr - with cells that are somewhat unorganized which secretes sex steroids and may also secrete cortisol. The medulla is the site of epinephrine and norepinephrine production.

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THYMUS

Each lobule of this gland has a darker staining cortex (left A) and a lighter staining medulla (left B). One outstanding feature of this organ is the presence of thymic roses/thymic corpuscles (C). This organ, large until adolescence, is important for the development of the immune system. The hormone produced by this gland is thymosin.

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PINEAL

The pineal sand (looks like ink spots to me) develops over time, so that older adults have considerably more than children. The hormone secreted by this gland is melatonin. The production of this hormone is greatest in the dark.

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OVARY

"A" marks the primordial or primary follicles in both micrographs. "B" is a Graafian follicle with its oocyte. Estrogen and progesterone are produced by the follicles under the influence of FSH and LH from the pituitary gland (hypophysis). The germinal epithelium (a single layer of cells surrounding this organ) is not easily seen at this magnification.

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TESTIS






The testis is composed of tightly coiled seminiferous tubules (A). Two are seen here in perfect cross section. ( Cut on other plains they may appear very elongated.) Spermatogenesis occurs in the seminiferous tubule resulting in the production of sperm. Between these tubules are interstitial cells (B), the producers of testosterone. The pituitary hormones FSH and LH are essential for proper functioning of this organ.

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This page was last updated in August, 1997.

All micrographs are the property of Sherri Wick. Students of Biology 2740 and 2840 are welcome to use this page in the study and review of lecture and lab materials in the Human Physiolgoy and Anatomy courses.

If you have comments about this Web site that you would like to share , please use the "Comments Page" available at this site.

 Author: Sherri Wick, Coordinator and Instructor - Human Physiology and Anatomy Laboratories
University of Nebraska at Omaha
Allwine Hall 211E, 554-2343
swick@cwis.unomaha.edu