Hypothalamus and Pituitary Microstructure

Question 1

Another name for Pituitary

Answer 1

Hypophyseal

Question 2

Another name for posterior pituitary

Answer 2

neurohypophysis (because its hormones are delivered to it via neuron axons)

Question 3

Another name for anterior pituitary

Answer 3

adenohypophysis

Question 4

Parts of the anterior pituitary

Answer 4

pars distalis
pars intermedia
pars tuberalis

Question 5

Parts of the posterior pituitary

Answer 5

pars nervosa
infundibular stalk
median eminence

Question 6

Pars distalis

Answer 6

Anterior. Continuous with pars tuberalis. Looks darker staining pink because highly cellular and vascularized. Cells are organized in hoards that are closely associated with capillaries (fenestrated).

Question 7

Median eminence

Answer 7

posterior. 2 halves of hypothalamus come together to form it. It is continuous with the infundibular stalk. Part of the posterior pituitary.

Question 8

Pars tuberalis

Answer 8

Anterior. continuous with pars distalis. Forms a sleeve around the infundibular stalk.

Question 9

How is the nucleus in the CNS different?

Answer 9

Is simply a group of nerve cell bodies

Question 10

Supraoptic and Paraventricular nuclei

Answer 10

produce ADH and oxytocin which are carrier via the neurons axons to the pars nervosa of the posterior pituitary. Run in the infundibular stalk.

Question 11

Defining histological feature of pars intermedia?

Answer 11

cysts whose function is unknown (appear clear on the slide). Cells look basophilic like they are filled with granules. Thin section.

Question 12

Histology of pars nervosa?

Answer 12

Looks like a much lighter pink, looser organization. Axons are unmyelinated and carry ADH and oxytocin to be stored in the terminal axons in the nervosa. Axon terminals end on the fenestrated capillaries without diaphragms which carry the hormones to the rest of the body. See lots of nuclei (glial cells aka pituicytes) nerve cell bodies are in the hypothalamus.

Question 13

Cells types of the pars distalis?

Answer 13

chromophils (basophil and acidophil) and chromophobes

Question 14

Basophil

Answer 14

Dark blue staining. Secretes a single hormone and are arranged in cords, surrounded by thin layer of CT.

Question 15

Acidophil

Answer 15

Pink/red staining. Arranged in cords. Secretes one type of homrone

Question 16

Chromophobes

Answer 16

Are chromophils that are colorless because they have released their hormones and no longer have granules. Is a transient state, will accumulate granules again and become stained.

Question 17

2 types of acidophils?

Answer 17

Growth Hormone (GH or Somatoropin- involved in growth and fuel metabolism) and prolactin (PRL- involved in mammary gland milk production)

Question 18

4 types of basophils?

Answer 18

1. Thyroid stimulating hormone (TSH)
2. Follicle stimulating hormone (FSH)
3. POMC
4. Luteinizing hormone (LH)

Question 19

How are hormones carried to the pars distalis?

Answer 19

via the hypophyseal portal system–blood supply. Hormones are produced by the hypothalamus and are either releasing or release-inhibiting hormones. This venous portal system allows the hormones to be transported without getting diluted too much.

Question 20

What does the superior hypophyseal artery supply?

Answer 20

• median eminence
• infundiubular stalk
• pars tuberalis

Question 21

What does the inferior hypophyseal artery supply?

Answer 21

pars nervosa

Question 22

Where is the primary and secondary plexus located?

Answer 22

primary plexus- median eminence and infundibulum

secondary plexus- pars distalis

Question 23

What is the hypophyseal portal system composed of?

Answer 23

1. primary plexus
2. portal venules
3. secondary plexus