Endo/Repro - Histology - Hypothalamus, Pituitary, & Pineal Glands; Thyroid Gland

Question 1

Describe the embryology of the adenohypophysis and neurohypophysis.

Answer 1

Adenohypophysis - oral ectoderm evaginates to form Rathke’s pouch

Neurohypophysis - diencephalon evaginates

Question 2

What is the pars nervosa?

What is the pars distalis?

Answer 2

Neurohypophyseal tissue;

adenohypophyseal tissue

Question 3

What type of capillary is especially abundant in endocrine tissues?

Answer 3

Fenestrated capillaries

Question 4

True/False.

Stroma is mainly reticular connective tissue.

Answer 4

True.

Question 5

What are the four main hypothalamic nuclei controlling pituitary function?

Answer 5

Supraoptic,

paraventricular,

medial preoptic,

arcuate

Question 6

In histological terms, what are the three types of cell found in the adenohypophysis?

Answer 6

• Chromophils
• Chromophobes
• Folliculostellate

Question 7

What histological process allows for the differentiation of different hormone-secreting cells in the adenohypophysis?

Answer 7

Immunohistochemistry

(antibodies to specific hormone or receptor)

Question 8

What are the two main types of chromophil in the adenohypophysis?

Answer 8

• Acidophils
• Basophils

Question 9

Do we know what function adenohypophyseal folliculostellate cells have?

Answer 9

No.

Question 10

What are the two types of adenohypophyseal acidophillic cells?

Answer 10

Somatotrophs,

lactotrophs

Question 11

What are the three types of adenohypophyseal basophillic cells?

Answer 11

Thyrotrophs,

gonadotrophs,

corticotrophs

Question 12

List each of the following as either an acidophil or basophil:

Somatotroph

Thyrotroph

Gonadotroph

Lactotroph

Corticotroph

Answer 12

Acidophil,

basophil,

basophil,

acidophil,

basophil

Question 13

Which hypothalamic nuclei produce the tropic hormones that travel through the hypothalamic-hypophyseal portal system?

Answer 13

Paraventricular,

medial preoptic,

arcuate

Question 14

Describe the following in terms of pituitary circulation:

Superior hypophyseal artery

Primary capillary plexus

Hypophyseal portal vein

Secondary capillary plexus

Answer 14

Question 15

Does the pars intermedia (histology: colloid and cuboidal cells) of the adenohypophysis secrete hormones?

Answer 15

Melanocyte-stimulating hormone

Question 16

What structures are labeled in this micrograph of the neurohypophysis and what functions do they perform?

Answer 16

Herring bodies (nerve endings full of secretory products)

Pituicytes (support)

Capillaries (blood supply)

Question 17

1. 90% of pineal gland cells are:
2. They produce:
3. The supportive cells are:

Answer 17

Pinealocytes,

melatonin;

Interstitial cells

Question 18

What are the dark clumps in the middle of this pineal gland?

Answer 18

Corpora arenacea (brain sand; calcified concretions)

Question 19

What effects does melatonin production have on gonadal effects?

Answer 19

Inihibition

Question 20

Pineal gland destruction in children can lead to what gonadal effect?

Answer 20

Precocious puberty

(melatonin is inhibitory)

Question 21

True/False.

Melatonin increases gonadal activity.

True/False.

Light inhibits melatonin release.

Answer 21

False.

Melatonin decreases gonadal activity.

True.

Light inhibits melatonin release (via norepinephrine release from the suprachiasmatic nucleus).

Question 22

Pineal gland sympathetic post-ganglionic control comes from which ganglia?

Answer 22

Superior cervical ganglia

Question 23

Which of the following has a stromal capsule:

Pituitary gland

Thyroid gland

Pineal gland

Answer 23

Pituitary gland (stromal)

Thyroid gland (stromal)

Pineal gland (pia mater capsule only)

Question 24

What is the basic histological structure of the thyroid gland?

Answer 24

Follicular cells surrounding colloid

Question 25

Which side of the thyroid follicular cells faces the colloid? Which side of the thyroid follicular cells is the location of TSH receptors?

Answer 25

The apical side; the basolateral cells

Question 26

Where are thyroid parafollicular cells located?

Answer 26

In interfollicular areas or within basal laminae of follicles

Question 27

Parafollicular C cells only make up ~0.1% of thyroid cells. What is the best method for distinguishing them from follicular cells.

Answer 27

**Electron microscopy** --\> Presence of granules = parafollicular C cells

Question 28

What thyroid cell is this?

Answer 28

Parafollicular C cell | (note: abundant granules)

Question 29

What are the three major cell types found in the parathyroid glands?

Answer 29

Chief cells (dark), oxyphils (eosinophilic), adipocytes (white)

Question 30

Upon what cell type does calcitonin act? To what end?

Answer 30

Osteoclasts; direct inhibition

Question 31

What renal effect does calcitonin have?

Answer 31

Increased excretion of _both_ calcium and phophate

Question 32

How do oxyphils of the parathyroid gland appear? What is their function?

Answer 32

Large, eosinophilic cells (often in groups); unknown

Question 33

When stimulated by PTH, what do osteoblasts secrete to stimulate osteoclasts?

Answer 33

RANK-L (ALP also released)

Question 34

How do parafollicular cells of the thyroid appear on light microscopy with H&E staining?

Answer 34

Light (little dye uptake); in between follicles

Question 35

How are relatively active thyroid follicles distinguished from relatively inactive follicles via light microscopy?

Answer 35

More vesicles/bubbles = more colloid reuptake = more activity

Question 36

Name a few example organs that could potentially produce tumors that secrete PTH-rp. What would this cause?

Answer 36

Lungs, ovaries, or breast tissue; humoral hypercalcemia of malignancy

Question 37

Approximately what percentage of the pancreas is made up of endocrine tissue?

Answer 37

1 - 2%

Question 38

What stain reacts with glucagon and can be used to highlight pancreatic α cells in the islets of Langerhans?

Answer 38

Silver stain

Question 39

What percentage of islet cells are α cells? And β cells? And δ cells?

Answer 39

20% 70% 10%

Question 40

In T1DM, β cells are \_\_\_\_\_\_\_\_\_\_\_\_. In T2DM, β cells are \_\_\_\_\_\_\_\_\_\_\_\_.

Answer 40

Reduced, variable

Question 41

In T1DM, the islets of Langerhans are characterized by a(n) \_\_\_\_\_\_\_\_\_\_\_\_. In T2DM, the islets of Langerhans are characterized by \_\_\_\_\_\_\_\_\_\_\_\_.

Answer 41

Lymphocytic infiltrate; amyloidosis

Question 42

What are the black spots seen in pineal gland histology?

Answer 42

Corpora arenacea ('brain sand'); calcific material that increases with age

Question 43

Short arteries of the adrenal gland first perfuse the _________ and then drain out through veins from the \_\_\_\_\_\_\_\_\_.

Answer 43

Cortex, medulla

Question 44

Both 11β-hydroxylase and 21β-hydroxylase deficiencies will result in increased ____________ production.

Answer 44

Androgen

Question 45

What is the structural difference between norepinephrine and epinephrine?

Answer 45

A single methyl group

Question 46

\_\_\_\_\_ 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**.

Answer 46

Short; long

Question 47

Why is it important that arterial blood reach the adrenal cortex *before* traveling to the adrenal medulla?

Answer 47

The blood picks up glucocorticoids in the cortex that aid in the **conversion of norepinephrine to epinephrine** in the medulla

Question 48

The main mass of the adenohypophysis is known as the pars \_\_\_\_\_\_\_\_\_\_\_. The main mass of the neurohypophysis is known as the pars \_\_\_\_\_\_\_\_\_\_\_.

Answer 48

Distalis; nervosa