8/3/2019 Pituitary Slides Final

1/18

Overview Endocrine GlandsBy Dr I Mackraj (0729085646)

Objectives : To understand thekey histological features of thefollowing glands

1. Pituitary Gland

2. Thyroid Gland3. Parathyroid Gland

4. Adrenal

5. Pancreas

NB: Pineal (self-study andpathology is coveredelsewhere)

8/3/2019 Pituitary Slides Final

2/18

Difference between endocrine andexocrine glands: In General

endocrine

8/3/2019 Pituitary Slides Final

3/18

INTRODUCTION : PITUITARYGLAND

LOCATION:

Bean shaped gland

Base of brain, beneath 3rd ventricle

Sits in the base of skull (sella turcica)

8/3/2019 Pituitary Slides Final

4/18

Embryological Origin

Posterior Pituitary : Downgrowth of nervous tissue from hypothalamusAnterior Pituitary: arises as an upgrowth from the roof of the primitive oralcavity Rathkes pouch

8/3/2019 Pituitary Slides Final

5/18

Downloaded from: StudentConsult (on 30 April 2009 08:26 AM)

2005 Elsevier

Parts: Neural & Epithelial origin

PARTS:Posterior Pituitary : (Neurohypophysis/pars Nervosa)Pars Intermedia :Vestigial cleft separates AP from Pars intermedia.

Anterior Pituitary (adenohypophysis)

8/3/2019 Pituitary Slides Final

6/18

Overview : Histologically dividedAP, PI & PP

8/3/2019 Pituitary Slides Final

7/18

Anterior Pituitary link toHypothalmus

Hormones from the Hypoathalamus control secretion in the pituitaryconducted from the median hypothalamic eminence to AP via a Pituitary

8/3/2019 Pituitary Slides Final

8/18

ANTERIOR PITUITARY

Consists of cords and clumps of epithelial cellsinterspersed with rich capillaries network(fenestrated)

Hormones cells are stored as secretory

granules (different sizes)

reticular fibres that support the cords of cells

Three cell types are found:

(a)Chromophobes (weakly staining cytoplasm)

(b) Chromophils (strongly staining) 2 types viz.

acidophil and basophil

8/3/2019 Pituitary Slides Final

9/18

Downloaded from: StudentConsult (on 1 August 2008 09:31 AM)

2005 Elsevier

Cells of AP:H&E shows strongly stained chromophils and weakly stainedchromophobes

chromophils

chromophobes

ChromophilDivided :A acidophilB basophil

8/3/2019 Pituitary Slides Final

10/18

8/3/2019 Pituitary Slides Final

11/18

Based on affinity for acidic dyes

There are 2 types of chromophils:

Acidophils- affinity for acidic dyes

Basophils affinity for basic dyes

Immunocytochemical and EM techniquesallow for differentiation into morespecific cell types:

There are 2 sub-types of acidophils:Mammotrophs produce PRL (20%)

Somatotrophs produce GH (50%)

8/3/2019 Pituitary Slides Final

12/18

There are 3 known types of basophils:

(i)Gonadotrophs secrete LH and FSH

(5%)

(ii) Thyrotrophs secrete TSH (5%)

(iii) Corticotrophs secrete ACTH andpossibly POMC**** (20%)

Acidophils form the bulk of the AP

Somatotrophs form the bulk of theacidophils

8/3/2019 Pituitary Slides Final

13/18

Hyperpigmentation (

ACTH (adrenocorticotropic hormone) issecreted by the AP-stimulates the adrenalgland-cortisol (stress hormone)

ACTH associated with hyperpigmentation ACTH cleaved into

Pro-opiomelanocorticotropin (***POMC) which

produces active compounds:Lipotropins, endorphins (endogenous opioids)

and MSH (melanocyte stimulating hormone)

8/3/2019 Pituitary Slides Final

14/18

SmallCysticSpacesFilledWithEosinophili

material

Basophilic cellsin clusters

Pars intermedia: secretes MSH

8/3/2019 Pituitary Slides Final

15/18

Posterior pituitary :

Made up of pituicytes and axons originating in supraoptic andparaventricular nuclei

ADH and oxytocin Downloaded from: StudentConsult (on 1 August 2008 09:31 AM) 2005 Elsevier

Distended ends ofaxon-containneurosecretory

granules

Posterior pituitary

H =Herringbodies

8/3/2019 Pituitary Slides Final

16/18

In Summary

8/3/2019 Pituitary Slides Final

17/18

Anterior Pituitary disorders

Commonest disease: pituitary adenoma

e.g. tumours of somatotrophs (GH) cancause giantism in children or acromegalyin adults

Rarely: disease blocking blood supply cancause necrosis of cells leading to failureof hormone output : panhypopituitarism

8/3/2019 Pituitary Slides Final

18/18

Tutorial

Describe the different parts of the PG

histologically; with regard to their mainhistological features