Pituitary/Pineal Gland: Histology

Question 1

Describe the development of the pituitary gland

Answer 1

Neurohypophysis (posterior lobe) develops from the neural ectoderm. Adenohypophysis (anterior lobe) develops from oral ectoderm aka Rathke’s pouch. Gland sits all cozy in the sella turcica (a depression in the sphenoid bone)

Question 2

Components of the adenohypophysis (anterior lobe)

Answer 2

Pars tuberalis (wraps around the infundibulum) (Tuberalis+infundibulum=neural stalk fyi)

pars distalis (pars anterior).

Question 3

Components of the neurohypophysis (posterior lobe)

Answer 3

Pars nervosa, infundibulum (contains the median eminence of tuber cinereum)

Question 4

Component of the intermediate lobe

Answer 4

Pars intermedia (EASY PEASY POGO STICK)

Question 5

Name the types of cells in the adenohypophysis (anterior pituitary). If you’re looking at a fuzzy picture, how will you tell them apart?

Answer 5

Chromophobe (lightly stained)

Basophil (blueberry)

Acidophil (pink)

Question 6

Name the acidophil hormones and their functions (briefly, more detail to come). Go!

Answer 6

Remeber APG. Both are protein hormones.

Prolactin: breast development and milk production

Growth hormone: muscle/bone growth

Question 7

Name the basophil hormones and their functions. GO GO GO

Answer 7

Remember BFLAT. All proteins.

FSH: follicle development, spermatogenesis

LH: follicle maturation (estrogen/progesterone synthesis) and ovulation. Testosterone synthesis.

ACTH: stimulates release of cortisol, aldosterone and androgens (water/salt balance)

TSH: stimulates release of thyroid hormone (energy balance)

Some extra:

Beta-Endorphin (β-END)

*Beta-Lipotropin (β-LPH)

Question 8

Chromophobes. Why we care.

Answer 8

Pale staining cells that lack cytoplasmic granules. 4 types:

1. Degranulated cells (used to be acidophils/basophils)
2. Precursor cells (undifferentiated)
3. Apoptotic cells
4. Follicular-stellate cells

Question 9

How big is a mammotroph (prolactin releasing cell)

Answer 9

MAMMOTH SIZED (500-700nm)

Question 10

How big is a somatotroph (GH releasing cell)

Answer 10

Medium size (300-400nm)

Question 11

How big is a gonadotroph (FSH, LH releasing cell)

Answer 11

Small size (150-250nm)

Question 12

How big is a thyrotroph (TSH releasing cell)

Answer 12

Tiny size (120-170nm)

Question 13

What kind of capillaries do you find in the pituitary?

Answer 13

Fenestrated (little bitty holes in the endothelial cells, complete basement membrane though). This allows hormones to get from the hypothalamus to the pituitary cells via the blood stream. Super duper.

Question 14

Describe release and feedback control of thyroid hormone

Answer 14

Neuroendocrine cells in the hypothalamus get activated by some neuron. Hypothalamus releases TRH (thyrotropin releasing hormone) to thyrotroph cells in the anterior pituitary. Thyrotroph cells release TSH which stimulates the thyroid follicular cells to release T3/T4 (thyroid hormones). T3/T4 inhibits the thyrotroph cells in the anterior pituritary and the neuroendoendocrine cells of the hypothalamus.

Question 15

Hormones of the intermediate lobe

Answer 15

Melanocyte-stimulating hormone (MSH)

Opioids (endorphins, dynorphins)

Question 16

Median eminence. What is it.

Answer 16

Convergence of hypothalamic neurons that release hormones to the posterior pituitary (the infundibulum in particular) via hypophyseal circulation (portal system)

Question 17

Pituicytes. What is it.

Answer 17

Glial cells of the posterior pituitary. Assist in the storage and release of neurohypophysial hormones

Question 18

Hormones of the posterior pituitary are produced by….

Answer 18

Paraventricular nucleus and supraoptic nucleus (of the hypothalamus)

Question 19

Pinealocyte. Vat iz it.

Answer 19

Primary cell of the pineal gland (shocking). A modified neural cell that enzymatically synthesizes melatonin. Melatonin is released at night.

Question 20

Walk me through how light influences the pineal gland

Answer 20

Light hits the eye, which sends a signal to the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN communicates with the pineal gland via sympathetic pathways and the superior cervical ganglion. Light inhibits melatonin release.

Question 21

What hormone can cause hyperplasia/hypertrophy of the pituitary gland

Answer 21

Estrogen (PREGGER LADIES)

Question 22

What hormones are released by the posterior pituitary

Answer 22

ADH and oxytocin. Too easy.

Question 23

What is a herring body

Answer 23

Accumulation of hormones in the hypothalamic neurons coming to the posterior pituitary. Accumulations are spaced along the length of the axon, not at axon terminal. They are visible under the Chrome Alum hematoxylin stain, and stain blue-gray or purple (think of a blue heron)

Question 24

The F is a colloid-body

Answer 24

Contained mostly within the pars intermedia, they are remainders of Rathke’s pouch (“collection of protein”). They stain robin egg blue with Martius-Scarlet-Blue stain. Don’t confuse with basophils. Basophils HAVE a nucleus. Colloid-filled cysts HAVE NO nucleus.

Question 25

What hormones are secreted by the anterior pituitary?

Answer 25

Think: FLAT PiG

FSH

LH

ACTH

TSH

ProlactIn

GH

Question 26

What kinds of cells do you find in the pars intermedia?

Answer 26

Basophils, Chromophobes and Colloid-cysts

Question 27

Brain sand. Not to be confused with beach sand that I would like to be sitting in right now.

Answer 27

Also known as the corpora arenacea, these are large mineral deposits found in the pineal gland

Question 28

Describe the release and feedback control of prolactin

Answer 28

The hypothalamus stimulates the anterior pituitary to release prolactin (TRH and oxytocin also stimulate prolactin release). Prolactin increases dopamine release from the hypothalamus, which inhibits the pituitary from releasing more prolactin.