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END 207: Histology > Pituitary gland > Flashcards

Pituitary gland Flashcards

1
Q

Histologically, pituitary gland is divided into

A

Adenohypophysis & Neurohypophysis

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2
Q

Adenohypophysis develops from

A

Oral ectoderm; by an upward growth from roof of oral cavity forming Rathke’s pouch

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3
Q

Neuorohypophysis develops from

A

Neuroectoderm; as downward growth from floor of diencephalon, being surrounded from below by Rathke’s pouch of Adenohypophysis

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4
Q

site of Pituitary gland

A

Sella Turcica

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5
Q

Pituitary gland is connected to hypothalamus via

A

infundibulum (stalk)

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6
Q

Components of Adenohypophysis of pituitary gland

A
  • pars tuberalis
  • Pars distalis
  • Pars intermedia
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7
Q

Components of neurohypophysis of pituitary gland

A
  • pars Nervosa
  • Infundibulum
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8
Q

groups of Cells of Pars distalis are seperated by

A

fenestrated capillaries

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9
Q

cells in pars distalis are divided into

A
  • Chromophobes (52%)
  • Chromophils (48%)
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10
Q

chromophobes cells can be either —-

A
  • Granular: secrete hormones
  • Non-granular: as stem cells or exhausted chromophils
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11
Q

Chromophils are divided into

A
  • Basophils
  • Acidophils
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12
Q

Enumerate acidophilic cells of the chromophils of pars distalis

A
  • Somatotrophs: secrete growth hormone
  • Mammotrophs: secrete prolactin hormone, stimulates milk secretion
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13
Q

Enumerate basophilic cells of the chromophils of pars distalis

A
  • Thyrotrophs
  • Corticotrophs
  • Gonadotrophs
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14
Q

Describe LM of Acidophils of pars distalis

A
  • Acidophilic granules (but basophilic cytoplasm)
  • Somatotrophs: spherical with central rounded nuclei, orangeophils
  • Mammotrophs: oval with central oval nuclei, carminophils
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15
Q

EM of Acidophils of Pars distalis

A

developed golgi, rER, mitochondria & secretory granules (in pregnancy & lactation, Mammotrophs organelles are enlarged)

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16
Q

Change in mammotrophs during pregnecy & after birth

A

become pregnency cells; due to high estrogen levels, they increase in size & number

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17
Q

Abnormal increase in GH secretion causes—

A
  • before closure of epiphyses–> Gigantism
  • after closure of epiphyses–> Acromegaly
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18
Q

Abnormal decrease in GH secretion causes—

A

Dwarfism

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19
Q

when decribing LM of Basophils of pars distalis, all basophils are rounded with central rounded nucleus, except for____

A

Corticotrophs; oval cell with eccentric nuclei

20
Q

Function of thyrotrophs

A

secrete TSH/ thyroid stimulating hormone/ thyrotropin:
* stimulate thyroid to secrete thyroid hormones T3 & T4

21
Q

Function of Corticotrophs

A

1.secrete Adrenocorticotrophic hormone (ACTH):
* Stimulate secretion of Cortisol from Adrenal cortex

2.secrete Melanocyte stimulating hormone (MSH): stimulates melanocytes to from Melanin

3.Endorphins
4.Lipotrophic factor

22
Q

Gonadotrophs are divided into

A
  • FSH (follicle stimulating hormone) secreting Cells
  • LH (Leutinising Hormone) secreting cells
23
Q

function of FSH

A

Females: Growth of Ovaries
Males: Spermatogenesis

24
Q

Function of LH

A

Females:
* Ovulation
* formation of Corpus Luteum

Males:
* changes name ICSH (interstitial cells stimulating hormone)
* stimulates interstitial cells of testis to secrete Testeosterone

25
Q

Describe Castration cells

A

Gondatrophs that undergo increase in number & size due to bilateral removal of testis (castration)

  • it gives signet ring appearance (accumulation of basophilic material pushes nucei peripheral)
26
Q

Upwards extension of Pars distalis that surrounds infundibulum is called____

A

Pars Tuberalis

27
Q

cells of Pars tuberalis have unknown functions, but some cells are ____

A

(basophilic) Gonadotrophs:
* LH secreting cells
* FSH secreting cells

28
Q

Difference between Pars intermedia in humans and some animals

A
  • in man it’s rudimentary
  • In some animals, it secrete MSH (melanocyte stimulating hormone), such as in reptiles
29
Q

Difference between MSH secretion in humans and animals

A
  • In some animals, it’s secreted by cells in the pars intermedia of pituitary gland
  • in humans, it is secreted by basophils, specifically corticotrophs, of Pars Distalis of the pituitary gland
30
Q

Tumours of Adenohypophysis are usually____

A

Benign

31
Q

Clinical diagnosis of tumours of Adenohypophysis can be confirmed by

A

immunocytochemical methods following Surgical removal

32
Q

Enumerate contents of Pars Nervosa

A
  1. Pituicytes
  2. Nerve fibers (with no nerve cells)
  3. Herring bodies
  4. fenestrated blood capillaries
33
Q

pituicytes are —

A

Neuroglial supporting cells

34
Q

Nerve fibers of Pars Nervosa form tract called —-

A

Hypothalamo-Hypophyseal tract

35
Q

Herring bodies are located at ____

A

axon terminals of the nerve fibers

36
Q

Contents of Herring bodies

A
  • Oxytocin
  • Vasopressin (ADH)
37
Q

Fenestrated blood capillaries of Pars Nervosa are surrounded by

A

Herring bodies

38
Q

Main Function of Pars Nervosa

A

Storage of ADH & Oxytocin secreted from paraventricular & supraoptic Nuclei of Hypothalamus

39
Q

Function of Oxytocin hormone

A
  • stimulate uterine contraction during labour
  • stimulate contraction of mammary gland myoepithelial cells —> milk ejection during lactation
40
Q

Describe blood supply of Pituitary gland

A

1.through primary capillary plexus (1), Superior hypophyseal Arteries supply:
* Hypothalamus
* Infundibulum (stalk)
* pars intermedia

2.1ry capillary plexus gives rise to portal veins at pars tuberalis, that give rise to 2ry capillary plexus which supplies Pars distalis

3.Inferior Hypophyseal Artery supplies Pars nervosa

41
Q

blood supply of Pars intermedia

A

Superior Hypophyseal Arteries

42
Q

blood supply of Pars Tuberalis

A

portal veins of 1ry capillary plexus

43
Q

blood supply of Pars Distalis

A

2ry capillary plexus

44
Q

blood supply of Pars Nervosa

A

Inferior Hypophyseal A.

45
Q

Describe how the release of inhibiting & stimulating hormones from the hypothalamus have an affect all the way down to cells of pars distalis of Pituitary gland

A

through the portal circulation:
hormones are transmitted from superior Hypophyseal A to 1ry capillary plexus, to portal veins, then to 2ry capillary plexus, where it reaches cells of Pars distalis

END 207: Histology (5 decks)

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