Endocrine ANAT/HIST Flashcards
What are characteristic features of Endocrine Tissues and Cells under the LIGHT MICROSCOPE?
- clumps/sheets/rows of cuboidal/polygonal cells
- vessels, extensive capillary network, specialisation e.g. portal arrangement
- CT capsule, framework
What are characteristic features of Endocrine Tissues and Cells under the TRANSMISSION ELECTRON MICROSCOPE?
- Prominent GA
- Prominent r/s ER
- Mitochondria
- SECRETORY GRANULES/VESICLES
- FENESTRATED CAPILLARIES
Regarding the parafollicular cells located within the follicles of the thyroid gland:
a) They are more numerous than follicular cells
b) they secrete parathyroid hormone
c) they do not contain secretory granules
d) they share a basement membrane with the follicular cells
CORRECT: d) They share a basement membrane with the follicular cells.
Some parafollicular cells are also found in the interstitial region between the follicles.
a) Follicular cells are much more numerous.
b/c) Parafollicular cells contain secretory granules & secrete calcitonin. Parathyroid hormone is secreted by the chief cells of the parathyroid gland.
Regarding the histological structure of the adrenal gland as seen in the light microscope:
a) The zona glomerulosa is the innermost layer of the cortex
b) The zona fasciculata consists of columns of large pale cells
c) The cells of the zona reticularis secrete aldosterone
d) The cells of the medulla are stimulated to secrete by ACTH
CORRECT: b) The zona fasciculata consists of columns of large pale cells.
a) The ZG is the OUTER or most superficial layer of the cortex.
c) The ZR secretes SEX STEROIDS. Aldosterone is secreted by the ZG
d) The cells of the medulla are stimulated to secrete by PREGANGLIONIC SYMPATHETIC NEURONS. ACTH stimulates the ZF and ZR to secrete (not the medulla)
DESCRIBE the structure of an ISLET OF LANGERHAN, as seen with the LIGHT MICROSCOPE, without the use of a diagram. (1/4 to 1/2 a page)
Under the LM the Islets of Langerhan appear as small spherical collections of cells scattered throughout the exocrine acini and ducts of the remainder of the pancreas. The cells are cuboidal/polygonal in shape and are of three main types, A cells, B cells and D cells. In routine histological stains the three types of cells cannot be readily distinguished however with special (eg Mallory-Azan, silver) or immunological stains they can be differentiated. B cells are the most numerous and make up about 70% of the Islet and secrete insulin. A cells make up abbout 20% of the cells and secrete glucagon and D cells make up about 10% of the cells and secrete somatostatin. There are several other types of cells in small numbers that secrete hormones that mainly act on the digestive tract. The Islets contain an extensive capillary network.
In a haematoxylin and eosin stained section of the parathyroid gland using the light microscope the feature that would best help identify the chief cells would be:
a) Their proximity to capillaries
b) Their smaller size
c) Their lighter staining
d) The presence of intracytoplasmic inclusions
The best answer is b. The chief cells are small darker staining cells while the oxyphil cells are larger more paler staining.
Re a) The capillary network appears throughout the tissue.
Re d) While the intracytoplasmic granules are evident at the EM level they are NOT in the LM with H&E staining.
In a haematoxylin and eosin stained section of the thyroid gland, viewed by the light microscope, which feature would best identify it as thyroid tissue?
a) The presence of extracellular colloid.
b) The presence of intracellular granules within the follicular cells.
c) The stratified nature of the follicular epithelium.
d) The absence of the staining of the follicular cell nuclei.
The best answer is a. The colloid collections are a key feature of thyroid tissue although some colloid is also present in part of the adenohypophysis.
Re b,c&d) The epithelium is simple in type, the nuclei stain and intracytoplasmic granules are not evident in the technique presented.
In a haematoxylin and phloxine stained section of the adrenal cortex using the LM the feature that would best help identify the zona fasciculata cells would be
a) Their flattened shape.
b) Their small size.
c) Their eccentrically placed nucleus.
d) Their pale staining.
The best answer is d. The ZF stands out because of its PALE STAINING along with the size and arrangement of the cells.
The cells are relatively LARGE, POLYHAEDRAL in shape with a CENTRAL nucleus.
Which of the following regarding endocrine tissues are True?
a) Except for the neurohypophysis and the thyroid tissue, they have a similar appearance when viewed under the light microscope.
b) They are very similar in a general way from other tissues observed in this course.
c) They have a relatively simple structure when captured by the electron microscope, but complicated under the light microscope.
d) They are collections of cuboidal (ish) shaped cells with a delicate connective tissue framework
e) They are surrounded by an extensive network of capillaries.
f) They have a large variation in cell types and are organisationally complex.
True: a, d, e
False:
b) Endocrine tissues differ significantly from other tissues
c) Simple under the LM; ultrastructurally complex (EM)
f) They LACK the variation in cell types and organisational complexity found in many other tissues.
Describe the hypothalamo-hypophyseal portal system.
A capillary plexus in the basal hypothalamus and a capillary plexus in the adenohypophysis joined by small relatively straight and parallel unbranching vessels. In addition, small hypophyseal arteries supply the proximal plexus and hypophyseal veins drain the distal plexus.
Which of the following cells are acidphilic and basophilic? Somatotrophs Thyrotrophs Corticotrophs Gonadotrophs Lactotrophs
Acidophilic - Somatotrophs and Lactotrophs
Basophilic - Thyrotrophs, Corticotrophs and Gonadotrophs
How does the arrangement of cells in the thyroid gland compare to that of the thyroid gland?
a) Thyroid has solid clumps
b) Parathyroid has single layered colloid containing sphere
c) Thyroid has follicular and parafollicular cells making up a stratified layer around a colloid containing sphere
d) Parathyroid varies between clumps and stratified layers
e) a and b
f) none of the above
f) none were correct, however a and b were close:
In the THYROID gland the cells are arranged as a SINGLE LAYERED COLLOID CONTAINING SPHERE and in the PARATHYROID gland as a SOLID CLUMP of cells.
In some particular aggregates of cells the nervous system has a marked effect or control on secretion.
Name 3 examples (of the tissues)
Hypothalamus, Pituitary, Pineal, Adrenal Medulla
