Endocrine Histology

Question 1

Identify the types of cells/structure indicated by each number

Answer 1

1. Chief cells (pinealocytes)
2. Interstitial cells (glial cells)
3. Blood vessels (capillaries)

Question 2

Identify the cells within the red circles

Answer 2

“Brain sand” or Corpora arenacea

Question 3

Name the fluid indicated by the blue circle.

How can you tell when one area is active or inactive?

Name the cells indicated by the orange circle that produce the fluid in the blue circle.

Answer 3

Colloid

Foamy appearance of the colloid

Follicular cells

Question 4

Name the type of cells indicated by the black circles

Answer 4

Parafollicular cells

Question 5

Describe the steps of the formation of the adenohypophysis

Answer 5

ectoderm from the roof of the stomadeum forms Rathke’s pouch

base of Rathke’s pouch constricts, separating it from the oral cavity

lumen of the Rathke’s pouch may persis as the residual lumen

Question 6

Describe the steps of the formation of the neurohypophysis

Answer 6

neuroectoderm of the ventral wall of the diencephalon evaginates to form the infundibulum

lumen of 3rd ventricle extends into infundibular stalk and persists as the infundibular stalk and persists as theinfundibular recess in some species (ex- pig, cat)

Question 7

List the types of cells in the pars distalis/hormones produced by each

Answer 7

Chromophobes (50%) (pale blue in trichrome)- degranulated cells and cells of unknown function

Chromophils:

   acidophils(40%)(tan in trichrome)-

somatotrophs- GH, STH

lactotrophs- prolactin

    basophils(10%)(dark blue in trichrome)-

thyrotrophs- TSH

gonadotrophs- FSH, LH (or ICSH)

corticotrophs- POMC cleaved to ACTH and LPH

Question 8

Name the type of cells in the pars intermedia/hormone produced

Answer 8

basophilic cuboidal cells- MSH

Question 9

Cells found in the pars nervosa (neurohypophysis)

Answer 9

axons- contain secretory granules

pituicytes- might function as neuroglia

Question 10

Give characterisics of the Thyroid gland

Answer 10

lies on the trachea just caudal to the larynx, lobes may be connected by and isthmus (fused in pigs)

imbalance of iodine creates Goiter

Question 11

Function of follicular cells

Answer 11

synthesize and iodinate thyroglobulin (stored as colloid)

thyroglobulin is taken back into cell and broken down by lysosomal enzymes into T3 (triiodothyronine) and T4 (thyroxine), which are then released basally into the bloodstream

cell structure: active- cuboidal to columnar, many microvilli, foamy colloid

inactive- squamous to cuboidal

Question 12

Functions of parafollicular cells

Answer 12

secrete calcitonin, which lowers blood calcium

neural crest cells migrate into ultimobranchial (5th) pharyngeal pouch, which fuses with developing thyroid; invade thyroid

Question 13

Cells of the parathyroid gland

Answer 13

Chief cells: dark cells are active; producing parathormone (elevates blood calcium, opposite action to thryoid C cells); light cells are inactive

Oxyphil cells (present in oxen, horses, man): function unknown but number increases with age

Question 14

Gross structure of adrenal gland

Answer 14

capsule, cortex (zona glomerulosa(arcuate)/zona fasciculata/zona reticularis);medulla

Question 15

Layers of the cortex (Superficial to deep)

Answer 15

Zona glomerulosa (arcuate)

Zona fasciculata

Zona reticularis

Question 16

Adrenal gland blood supply

Answer 16

Several major arteries branch into a plexus of arterioles under capsule, then there are 3 systems:

subcapsular capillary plexus drains to subcapsular veins

cortical blood sinusoids drain to medullary veins

medullary arteries from capillary bed in medulla that drains to medullary veins

Question 17

Identify the layer of the cortex indicated by the arrow, what does this layer produce and what species you would see it in

What is this region called when observed in tissue from a pig, cat or horse?

Answer 17

Zona glomerulosa

undulating lines of cells steroid producing cells, lipid droplets, tubular mitochondria, extensive smooth endoplasmic reticulum

Zone arcuate

Question 18

Identify the layers of the cortex and name what they produce

Answer 18

1. Zona fasciculata- radial cords of cells, cuboidal cells (spongiocytes) arranged in radial cords, produces glucocorticoids, including cortisol, act on the medulla
2. Zona reticularis- randomly oriented cells, remnant of the fetal cortex, freely anastomosing cords, produces sex steroids, normally precursor to testoterone and estradiol

Question 19

Name the indicated parts of the adrenal gland

Answer 19

1. Medulla
2. Capsule
3. Cortex

Question 20

Identify the lumen indicated by the arrow.

What is its developmental origin?

Answer 20

Residual lumen

Ectodermal; Rathke’s pouch