Endo/Repro - Histology - Hypothalamus, Pituitary, & Pineal Glands; Thyroid Gland Flashcards
Describe the embryology of the adenohypophysis and neurohypophysis.
Adenohypophysis - oral ectoderm evaginates to form Rathke’s pouch
Neurohypophysis - diencephalon evaginates
What is the pars nervosa?
What is the pars distalis?
Neurohypophyseal tissue;
adenohypophyseal tissue
What type of capillary is especially abundant in endocrine tissues?
Fenestrated capillaries
True/False.
Stroma is mainly reticular connective tissue.
True.
What are the four main hypothalamic nuclei controlling pituitary function?
Supraoptic,
paraventricular,
medial preoptic,
arcuate
In histological terms, what are the three types of cell found in the adenohypophysis?
- Chromophils
- Chromophobes
- Folliculostellate
What histological process allows for the differentiation of different hormone-secreting cells in the adenohypophysis?
Immunohistochemistry
(antibodies to specific hormone or receptor)
What are the two main types of chromophil in the adenohypophysis?
- Acidophils
- Basophils
Do we know what function adenohypophyseal folliculostellate cells have?
No.
What are the two types of adenohypophyseal acidophillic cells?
Somatotrophs,
lactotrophs
What are the three types of adenohypophyseal basophillic cells?
Thyrotrophs,
gonadotrophs,
corticotrophs
List each of the following as either an acidophil or basophil:
Somatotroph
Thyrotroph
Gonadotroph
Lactotroph
Corticotroph
Acidophil,
basophil,
basophil,
acidophil,
basophil
Which hypothalamic nuclei produce the tropic hormones that travel through the hypothalamic-hypophyseal portal system?
Paraventricular,
medial preoptic,
arcuate
Describe the following in terms of pituitary circulation:
Superior hypophyseal artery
Primary capillary plexus
Hypophyseal portal vein
Secondary capillary plexus
Does the pars intermedia (histology: colloid and cuboidal cells) of the adenohypophysis secrete hormones?
Melanocyte-stimulating hormone
What structures are labeled in this micrograph of the neurohypophysis and what functions do they perform?
Herring bodies (nerve endings full of secretory products)
Pituicytes (support)
Capillaries (blood supply)
- 90% of pineal gland cells are:
- They produce:
- The supportive cells are:
Pinealocytes,
melatonin;
Interstitial cells
What are the dark clumps in the middle of this pineal gland?
Corpora arenacea (brain sand; calcified concretions)
What effects does melatonin production have on gonadal effects?
Inihibition
Pineal gland destruction in children can lead to what gonadal effect?
Precocious puberty
(melatonin is inhibitory)
True/False.
Melatonin increases gonadal activity.
True/False.
Light inhibits melatonin release.
False.
Melatonin decreases gonadal activity.
True.
Light inhibits melatonin release (via norepinephrine release from the suprachiasmatic nucleus).
Pineal gland sympathetic post-ganglionic control comes from which ganglia?
Superior cervical ganglia
Which of the following has a stromal capsule:
Pituitary gland
Thyroid gland
Pineal gland
Pituitary gland (stromal)
Thyroid gland (stromal)
Pineal gland (pia mater capsule only)
What is the basic histological structure of the thyroid gland?
Follicular cells surrounding colloid
Which side of the thyroid follicular cells faces the colloid?
Which side of the thyroid follicular cells is the location of TSH receptors?
The apical side;
the basolateral cells
Where are thyroid parafollicular cells located?
In interfollicular areas or within basal laminae of follicles
Parafollicular C cells only make up ~0.1% of thyroid cells.
What is the best method for distinguishing them from follicular cells.
Electron microscopy –>
Presence of granules = parafollicular C cells
What thyroid cell is this?
Parafollicular C cell
(note: abundant granules)
What are the three major cell types found in the parathyroid glands?
Chief cells (dark),
oxyphils (eosinophilic),
adipocytes (white)
Upon what cell type does calcitonin act?
To what end?
Osteoclasts;
direct inhibition
What renal effect does calcitonin have?
Increased excretion of both calcium and phophate
How do oxyphils of the parathyroid gland appear?
What is their function?
Large, eosinophilic cells
(often in groups);
unknown
When stimulated by PTH, what do osteoblasts secrete to stimulate osteoclasts?
RANK-L
(ALP also released)
How do parafollicular cells of the thyroid appear on light microscopy with H&E staining?
Light (little dye uptake);
in between follicles
How are relatively active thyroid follicles distinguished from relatively inactive follicles via light microscopy?
More vesicles/bubbles = more colloid reuptake = more activity
Name a few example organs that could potentially produce tumors that secrete PTH-rp.
What would this cause?
Lungs, ovaries, or breast tissue;
humoral hypercalcemia of malignancy
Approximately what percentage of the pancreas is made up of endocrine tissue?
1 - 2%
What stain reacts with glucagon and can be used to highlight pancreatic α cells in the islets of Langerhans?
Silver stain
What percentage of islet cells are α cells?
And β cells?
And δ cells?
20%
70%
10%
In T1DM, β cells are ____________.
In T2DM, β cells are ____________.
Reduced,
variable
In T1DM, the islets of Langerhans are characterized by a(n) ____________.
In T2DM, the islets of Langerhans are characterized by ____________.
Lymphocytic infiltrate;
amyloidosis
What are the black spots seen in pineal gland histology?
Corpora arenacea (‘brain sand’);
calcific material that increases with age
Short arteries of the adrenal gland first perfuse the _________ and then drain out through veins from the _________.
Cortex,
medulla
Both 11β-hydroxylase and 21β-hydroxylase deficiencies will result in increased ____________ production.
Androgen
What is the structural difference between norepinephrine and epinephrine?
A single methyl group
_____ arteries of the adrenal gland first perfuse the cortex and then drain out through veins from the medulla.
_____ arteries of the adrenal gland first perfuse the medulla and then drain out through veins from the medulla.
Short;
long
Why is it important that arterial blood reach the adrenal cortex before traveling to the adrenal medulla?
The blood picks up glucocorticoids in the cortex that aid in the conversion of norepinephrine to epinephrine in the medulla
The main mass of the adenohypophysis is known as the pars ___________.
The main mass of the neurohypophysis is known as the pars ___________.
Distalis;
nervosa
