Endocrine System Organs and Tissues: Pituitary Adrenals Pancreas - - PowerPoint PPT Presentation

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Endocrine System Organs and Tissues: Pituitary Adrenals Pancreas - - PowerPoint PPT Presentation

Nov 11, 2022 110 likes •517 views

Endocrine System Organs and Tissues: Pituitary Adrenals Pancreas Thyroid Parathyroids Bruce A. Fenderson, Ph.D. Pathology, Anatomy & Cell Biology Sidney Kimmel Medical College Bruce.Fenderson@Jefferson.edu 1 Mechanisms

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Endocrine System

Bruce A. Fenderson, Ph.D. Pathology, Anatomy & Cell Biology Sidney Kimmel Medical College Bruce.Fenderson@Jefferson.edu Organs and Tissues:

  • Pituitary
  • Adrenals
  • Pancreas
  • Thyroid
  • Parathyroids

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Mechanisms of Cell Communication

  • Endocrine
  • Paracrine, autocrine
  • Synaptic
  • Neuroendocrine

From Rubin’s Pathology, 2007 2

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Development of the Pituitary

(Neurohypophysis & Adenohypophysis)

From Junqueira’s Basic Histology Text and Atlas 3

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Pituitary Gland (Master Gland)

From Wheater’s Functional Histology 4

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Hypothalamo - Hypophyseal System

Superior Hypophyseal Artery Inferior Hypophyseal Artery

  • Oxytocin (PV)
  • ADH (SO)

Hypothalamic Releasing Hormones Herring Bodies

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Anterior and Posterior Pituitary

From Wheater’s Functional Histology

Primary Capillary Plexus Secondary Capillary Plexus

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Anterior Pituitary (Pars Distalis)

  • Acidophils
  • Basophils
  • Chromophobes
  • Somatotrophs
  • Lactotrophs
  • Corticotrophs
  • TSH, MSH, FSH
  • Glandular epithelial cells with

fenestrated capillaries

  • Mixture of cell types producing

different polypeptide hormones

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Immunolabeling Can Be Used to Localize Specific Pituitary Hormones

  • Identification of

hormone-producing cells using specific antibodies

  • Method is used to

help establish tumor diagnosis (e.g., type

  • f pituitary adenoma)

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Dense, Membrane-Bound Secretory Granules Contain Pituitary Hormones

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Pars Intermedia

  • Epithelial cells

representing the residuum of Rathke’s pouch

  • Cords and

follicles that produce some melanocyte- stimulating hormone (MSH)

Anterior Pituitary Posterior Pituitary

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Craniopharyngioma

(tumor derived from remnants of Rathke’s pouch)

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Posterior Pituitary (Pars Nervosa)

  • Pituicytes - 25% of cells
  • Non-myelinated axons from

PV & SO nuclei

  • Herring bodies (storage)
  • ADH & Oxytocin
  • Fenestrated capillaries

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Herring Bodies in Neurohypophysis (dilated terminals of axons)

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Multiple effects of pituitary hormones

  • n target organs

with feedback inhibition…

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Adrenal (Suprarenal) Glands

  • Developmentally

regulated glands

  • Pituitary-dependent

function (ACTH)

  • Extra-adrenal cortical and

medullary tissues (relevant to rare tumors)

from Junquiera and Carneiro, Basic Histology

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Adrenal Cortex and Medulla

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Vascular Supply to the Adrenals

  • Cortex
  • Medull

a

Glomerulosa Fasiculata Reticularis

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Adrenal Zones and Hormones

***Zona Glomerulosa

Mineralocorticoid (aldosterone)

***Zona Fasiculata

Glucocorticoids (cortisol)

***Zona Reticularis

Weak androgens

***Medulla

Epinephrine, norepinephrine Cap

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Zona Glomerulosa (Aldosterone)

  • Thin outer zone

adjacent to capsule

  • Small clusters of cells

continuous with cords below

  • Aldosterone secretion

regulated primarily by the renin-angiotensin system

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Zona Fasiculata (Cortisol)

  • Middle and broadest of the 3

cortical zones

  • Narrow cords of secretory

cells with intracellular lipid droplets in long parallel columns (“spongyocytes”)

  • Separated by supporting

tissue containing sinusoidal capillaries

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Zona Reticularis (Weak Androgens)

Medulla Glandular epithelium arranged in cords and nests.

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Lipid Droplets in Steroid-Secreting Cells of the Adrenal Cortex

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Congenital Adrenal Hyperplasia

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Adrenal Medulla

  • Cords of glandular

epithelial cells supported by reticular fiber network

  • Neural crest cells
  • Modified sympathetic,

postganglionic neurons

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Chromaffin Cells Secrete Catacholamines*

A – Adrenaline (epinephrine) N – Noradrenaline (norepinephrine)

  • Stress response stimulated by

cholinergic endings of pre- ganglionic sympathetic nerves

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Endocrine Pancreas (Islets)

  • Islets of Langerhans
  • Micro-organs (approx. one

million per pancreas)

  • Polygonal cells with fine

reticular fiber capsule

  • Beta cells (70%) synthesize

insulin

  • Alpha cells (20%)

synthesize glucagon

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Blood Supply to Pancreatic Islets

  • 1-3 arterioles per islet
  • Branched, fenestrated capillaries
  • Venules drain to interlobular veins

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Localization of Pancreatic Hormones

  • Insulin
  • Glucagon
  • Somatostatin
  • VIP

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Thyroid Gland

  • Pituitary-dependent

endocrine organ (TSH)

  • Regulation of basal

metabolic rate

  • Extracellular storage of

hormone as colloid (thyroglobulin  T3, T4)

  • Highly vascularized tissue
  • Follicular and para-

follicular cells (C-cells)

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Thyroid Follicles Filled with Colloid

  • Follicles are

distended with colloid

  • Diameter is

variable

  • Range of

epithelial cell morphologies

  • Fenestrated

capillaries

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Follicles Store Thyroglobulin

  • Follicles store thyroid

hormone precursor (3 months)

  • Pituitary-derived TSH

stimulates thyroglobulin uptake and intracellular processing by epithelial cells

  • Active T3 and T4 are then

discharged into capillaries.

  • Size of follicles and lining cells

varies according to their activation state

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Calcitonin Producing C-Cells

  • Scattered neuroendocrine cells

from neural crest reside within the basal lamina of the follicle or in clusters between follicles

  • Referred to as parafollicular or

clear C-cells

  • Synthesize calcitonin to

decrease serum calcium

  • Medullary-type thyroid carcinoma

is derived from these C-cells

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Hyperthyroidism

  • Normal regulation of thyroid follicular

cells by pituitary TSH is circumvented by the production of anti-TSH receptor antibodies (autoimmune disease).

  • The result is unrelenting stimulation of

the thyroid gland and clinical features

  • f hyperthyroidism (Graves disease).

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Parathyroid Glands (4)

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Parathyroid Glandular Epithelium

  • Cord-like secretory cells and

adipose tissue (A). Adipose tissue increases significantly with patient age.

  • Composed of two cells types:

chief cells (principal cells) and oxyphil cells.

  • Chief cells synthesize and

secrete parathyroid hormone (PTH) in response to changes in blood calcium.

Oxyphil Cells Adipocytes Chief Cells

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Parathyroid Gland (H & E)

  • Chief cells (principal

cells) secrete PTH to increase serum Ca

  • Capillaries
  • Oxyphil cells

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Diffuse Neuroendocrine System

An example of the diffuse neuroendocrine system is gastrin-producing cells of stomach (APUD System). Enteroendocrine cells may be located at any level in the mucosa, from the base of glands to the tips of villi.

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Summary of Key Points

  • Pituitary (anterior & posterior lobes)
  • Adrenals (cortex 3 layers & medulla)
  • Pancreas (islets of Langerhans)
  • Thyroid (follicular & parafollicular C-cells)
  • Parathyroid (chief & oxyphil cells)

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Endocrine Organs Thank you… Questions?