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MBBS II ERS > L02 - Development, Structure of Pituitary Gland > Flashcards

L02 - Development, Structure of Pituitary Gland Flashcards

1
Q

Anatomical position of Pituitary gland?

A

in sella turcica / hypophysial fossa

(depression of sphenoid bone on floor of anterior cranial cavity)

Anatomically connected to brain but sits outside BBB

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2
Q

Describe the formation of pituitary gland?

A
  1. Neural component (neuroectoderm) evaginates from the floor of diencephalon&raquo_space; grows caudally&raquo_space; Posterior pituitary (neurohypophysis)
  2. Oral component (oropharynx ectoderm) arises as an outpocket from the roof of primitive mouth&raquo_space; migrate superiorly, forms Rathke’s pouch and lose connection with oral cavity&raquo_space; Anterior pituitary (adenohypophysis)

2 lobes fuse to form p. gland

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3
Q

Origin of Pars Intermedia?

A

dorsal part of the Rathke’s pouch

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4
Q

Origin of pars nervosa?

A

from neuroectoderm, continuous with posterior lobe of pituitary

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5
Q

Origin of pars distalis?

A

Anterior side of Rathke’s pouch

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6
Q

Origin of pars tuberalis?

A

Extension of Rathke’s pouch» surround infundibulum

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7
Q

Define the 3 regions of the anterior pituitary?

A

separated by indistinct boundaries:
▪ pars distalis = anterior region
▪ pars intermedia = divide 2 lobes
▪ pars tuberalis = wrap around infundibulum

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8
Q

Arterial and venous supply of pituitary gland?

A

1) L/R superior hypophyseal arteries form 2 plexuses of Hypophyseal Portal System:
i) Primary capillary plexus supply Infundibulum/ neural stalk + Median eminence
ii) Secondary capillary plexus drain Adenohypophysis/ anterior lobe

2) L/R inferior hypophyseal arteries supply Neurohypophysis/ post. lobe + infundibulum

> > efferent hypophyseal veins&raquo_space; cavernous sinus

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9
Q

Which lobe of the pituitary does not have direct arterial supply?

A

Anterior***

anterior lobe is mainly supplied by the Hypohyseal portal system

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10
Q

List the hypothalamuc nuclei linked to the anterior pituitary?

A

Ant =
• Dorsal medial, ventral medial and infundibular nuclei
• paraventricular nuclei (PVN) (Parvocellular neurosecretory neurons)

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11
Q

Which region of the anterior pituitary is hormone secreting?

A

Pars distalis

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12
Q

Describe the ultrastructure of Pars Distalis in ant. pit.?

A

Hormone-secreting cells in clusters/ cords

surrounded by fibrous tissue, capillaries

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13
Q

Define the 5 secretory cell types in pars distalis and their staining + major secretion.***

A

Acidophilic:

  • Somatotrope = Somatotrophin or GH
  • Lactotrope = Prolactin

Basophilic:

  • Gonadotrope = FSH, LH
  • Thyrotrope = TSH
  • Corticotrope = ACTH
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14
Q

Define the 3 cell types in pars distalis by H&E staining.

A

1) Chromophobes (no staining)
2) Chromophils:
a) Acidophils = red
b) Basophils = violet

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15
Q

Define the colours of the 3 cell types in pars distalis by PAS staining.

A

1) Chromophobes (no staining)
2) Chromophils:
a) Acidophils = Orange/yellow
b) Basophils = Magenta

RBC, vessels = green

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16
Q

Describe the organization of cells and staining of Pars intermedia?

A

Cords and follicles, at junction between anterior, posterior lobes, remnant from Rathke’s pouch

weakly basophilic with basophilic granules

17
Q

Describe the organization of cells of Pars tuberalis?

A

funnel-shaped region wrapping around infundibulum

Arranged in cords along blood vessels

weak Gonadotrophin-secretion

18
Q

List all the hormones secreted form the anterior pituitary (9)

A
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH)
  • Growth hormone (GH) or somatotropin
  • Melanocyte-stimulating hormone (MSH)
  • Beta-endorphin
  • Lipotropin
  • Prolactin
19
Q

List all the hormones secreted from posterior pituitary?

A
  • Antidiuretic hormone (ADH)

* Oxytocin

20
Q

Which hormones secreted from ant. pituitary are trophic?

A
  • Thyroid-stimulating hormone (TSH)
  • Adrenocorticotropic hormone (ACTH)
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH)
21
Q

Describe how hypothalamic neurons control the pars distalis in Anterior pituitary? ** think about the portal system**

A

dorsal medial, ventral medial and infundibular nuclei of hypothalamus&raquo_space; produce neurohormones

> > carried along axon and stored in Median Eminence in infundibulum, rich vascular supply by primary capillary plexus

> > Secrete into surrounding perivascular connective tissue spaces

> > transport by hypothalamo-hypophysial portal system to Ant. pituitary (pars distalis)

> > Pars distalis release hormones into secondary capillary plexus into venous sys.

22
Q

Describe how hypothalamic neurons control posterior pituitary hormone secretion?

A

supraoptic and paraventricular nuclei of the hypothalamus

> > produce posterior pituitary hormones

> > transported along hypothalamo-hypophyseal axon tract

> > vesicles accumulate and stored at axonal ends = HERRING BODIES

> > release into blood capillaries and veins

23
Q

How are neurohormones in the pars nervosa carried from thalamus to axon endings?

A

Via specific transport protein Neurophysin > carry Vp and oxytocin within pars nervosa

24
Q

Name the releasing/ inhibiting hormones of FSH and LH?

A

GnRH = stim

25
Q

Name the releasing/ inhibiting hormones of ACTH

A

CRH = stim

26
Q

Name the releasing/ inhibiting hormones of TSH

A

TRH = stim

27
Q

Name the releasing/ inhibiting hormones of Prolactin

A

PRH = stim

PIH +Dopamine = inhibit

28
Q

Name the releasing/ inhibiting hormones of GH/ somatotropin

A

Growth hormone releasing hormone = stim

Somatostatin = inhibit

29
Q

Name and describe function of the glial cell in posterior pituitary?

A

Pituicytes = modified glial cells in post. pituitary

Support, nourish and control activity of neurosecretory axons

MBBS II ERS (37 decks)

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