Endocrine System
Dr..Deepak N.Khedekar
Asst professor
Dept of Anatomy

LTMMC & GH,MUMBAI
2013.
The Endocrine System…
• This system is comprised of a variety of ductless glands.
• Some exist as discrete organs, while o...
Hormones …
–
–
–
–
–

are “messenger molecules”
Circulate in the blood
Act on distant target cells
Target cells show recep...
Endocrine Organs
• Cells forming endocrine organs
–
–
–
–

Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal: 2 gla...
Pituitory gland…
1.Hypophysis (Pituitary Gland)
• The hypophysis consists of glandular(Adenohypophysis) &
nervous portions(Neurohypophysis)...
Hypophysis cerebri…
Anterior Pituitary (Pars Distalis /Pars Anterior)
• Cells can be divided into two classes on the
basis of their staining c...
Anterior pituitory…
Chromophil:
 Acidophils ;
 strongly-staining, acidophilic

cytoplasm due to granules.
 cells are la...
Anterior pituitory…
Chromophobe clear, faintly-staining, sparse
cytoplasm.
 Do not have granules
 Indistinct cell outli...
Pars Intermedia…
• Intermediate portion of
pituitary
• part of the adenohypophysis,
• is non-neural.
• composed of a thin ...
Pars Nervosa…
• is a downgrowth from the
hypothalamus
• Exhibits characteristics of nervous
tissue.
• Axon terminals withi...
Pars nervosa…
• Pituicytes :
 Glial cells, variable in cell size
and shape.
 barely visible having orange
stained cytopl...
Thyroid gland…
Thyroid Gland-General Structure
•

It stores the inactive form of
hormone extracellularly in
follicles .
• General Structu...
follicles -of various sizes,
 filled with pink-stained colloid
and lined by cuboidal epithelial
cells. These are the
 fu...
Thyroid Follicles
• Follicular epithelium:
 vary from high cuboidal to low
cuboidal ; reflects the level of
follicle secr...
Parafollicular Cells
 Found scattered singly or in
small groups present in
periphery of the follicles ,
 cells are respo...
Parafollicular Cell…
 can be distinguished from
follicular cells because
they are large oval have
eccentrically-placed
nu...
Thyroid gland…
Parathyroid Glands…
General Structure :
 Thin C.T. capsule that
surrounds each gland and
gives rise to internal septa.
 ...
Parathyroid Glands-Parenchyma
 present as a mass of crowded
single cells, not arranged as
follicles. It consist of 2 type...
Parathyroid Glands…
Oxyphil cells:
 single or clumps of larger
cells with acidophilic
(oxyphilic), cytoplasm
with dark st...
Adrenal gland…
Adrenal Glands…
Like the pituitary, they are composed
of two distinctly different components,
one of mesothelial origin an...
Adrenal Cortex…
• The cortex is divided into three layers:
– Zona glomerulosa
– Zona fasciculata
– Zona reticularis

medul...
Adrenal Cortex: Zona Glomerulosa
Identify…
• outermost cortical layer , and
note the presence of columnar
epithelial cells...
Adrenal Cortex: Zona Fasciculata…
• Note that this is the broadest,
lightest-staining of the three
cortical zones, with ep...
Adrenal Cortex: Zona Reticularis…
• Note that the epithelial cells of
this innermost, prominently
stained zone are arrange...
Adrenal Medulla: Chromaffin Cells
• Derived from neural crest, cells
of the medulla are functionally
equivalent to postgan...
Adrenal Medulla: Chromaffin Cells
Note that chromaffin cell
cytoplasm is quite
basophilic, compared to
the acidophilia of ...
Adrenal Medulla: Blood Supply
• The medullary capillary
network receives blood from a
capsular plexus both indirectly,
via...
Pineal Gland-General Structure
• The pineal gland is an evagination of the
diencephalon of the brain, and contains highly
...
Pineal Gland-Parenchyma
• The parenchyma contains two cell types,
pinealocytes and neuroglia.
• The pinealocytes are modif...
Pineal Gland-Pineal Sand
• Basophilic, extracellular
concretions . They are often
calcified, which makes the
pineal gland ...
Epiphysis (Pineal Gland)
• The pineal is innervated by
unmyelinated axons of
postganglionic sympathetic
neurons. This is a...
Endocrine Pancreas: Islets of Langerhans
• The pancreas is a mixed exocrine
and endocrine gland.
General Structure
• Note ...
Islet of Langerhans…
• Consist of 3 types of cells
 Alpha cells (30%)
Stains pinks present
more on peripheral region

 B...
Clinical Histology
1.Goiter (Multinodular)
•

common cause of overactivity
of the thyroid gland
(hyperthyroidism).
• Incre...
3. Hashimoto's Thyroiditis:
• Autoimmune condition in
which the immune system
attacks the thyroid, causing
a reduction in ...
4.Adrenal Atrophy:
– Hypoplasia (decrease in cells) usually in the cortex but
also gaps in the medulla
– Proliferation of ...
5.Hyperparathyroidism (bone):
– Within the bone spicules, you can see osteoclasts
degrading the bone (more osteoclasts tha...
7.Pituitary Acidophilic Adenoma:
– Tumors tend to be in the anterior pituitary; monoclonal
proliferations of 1 of the 3 co...
Thank u.
Histology of Endocrine system.
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Histology of Endocrine system.

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Histology of Endocrine System.

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Histology of Endocrine system.

  1. 1. Endocrine System Dr..Deepak N.Khedekar Asst professor Dept of Anatomy LTMMC & GH,MUMBAI 2013.
  2. 2. The Endocrine System… • This system is comprised of a variety of ductless glands. • Some exist as discrete organs, while others are associated with exocrine glands and/or found within complex organs. • All endocrine glands secrete their products (hormones) into the connective tissue surrounding the secretory elements; from there, those products enter the blood or lymph, in which they travel to their target organs. • While protein and steroid hormones differ in mechanism, the effects of both are mediated by specific receptors in their target cells.
  3. 3. Hormones … – – – – – are “messenger molecules” Circulate in the blood Act on distant target cells Target cells show receptors to respond to the hormones The effects are dependent on the programmed response of the target cells – Hormones are just molecular triggers • Basic categories of hormones… – Amino acid based: modified amino acids (or amines), peptides (short chains of amino acids), and proteins (long chains of amino acids) – Steroids: lipid molecules derived from cholesterol 3
  4. 4. Endocrine Organs • Cells forming endocrine organs – – – – Pituitary gland Thyroid gland Parathyroid glands Adrenal: 2 glands Cortex Medulla -Pineal gland • Endocrine cells in other organs – – – – Pancreas Thymus Gonads Hypothalamus • Isolated endocrine cells-APUD cell system 4
  5. 5. Pituitory gland…
  6. 6. 1.Hypophysis (Pituitary Gland) • The hypophysis consists of glandular(Adenohypophysis) & nervous portions(Neurohypophysis) •    •  At low power, identify: Adenohypophysis: Pars anterior (pars distalis; anterior pituitary). Pars intermedia( remnant of rathke pouch rudimentary in human beings) . Pars tuberalis Neurohypophysis: Pars nervosa ( posterior pituitary) consist of median eminence and infundibulum.
  7. 7. Hypophysis cerebri…
  8. 8. Anterior Pituitary (Pars Distalis /Pars Anterior) • Cells can be divided into two classes on the basis of their staining characteristics: • Chromophils ("color-loving"), and chromophobes ("color-fearing"). • Chromophils are further classified as acidophils and basophils. • Each cell type produces only one type of hormone. • parenchyma consists of secretory epithelial cells arranged in anastomosing cords and clusters. • Abundant sinusoidal capillaries with fenestration
  9. 9. Anterior pituitory… Chromophil:  Acidophils ;  strongly-staining, acidophilic cytoplasm due to granules.  cells are larger,most abundant than chromophobes.  well developed cell outline  Basophils-  Cells are variable in sixe and shape with basophilic cytoplasm.  secretory granules responsible for the staining characteristics of these cells are.
  10. 10. Anterior pituitory… Chromophobe clear, faintly-staining, sparse cytoplasm.  Do not have granules  Indistinct cell outline  Represent chromophil without granules or stem cells  Sinusoidal Capillaries in Anterior Pituitary  Chromophil granules are dense cored vesicles
  11. 11. Pars Intermedia… • Intermediate portion of pituitary • part of the adenohypophysis, • is non-neural. • composed of a thin layer of epithelial cells, which enclose colloid-filled spaces. • Identify colloid vesicles, and the surrounding low columnar cells .
  12. 12. Pars Nervosa… • is a downgrowth from the hypothalamus • Exhibits characteristics of nervous tissue. • Axon terminals within this area originate from cells in the hypothalamus; those in the supraoptic nucleus produce ADH (vasopressin), while those in the paraventricular nuclei produce oxytocin. • Cell bodies of these neurons are located in the hypothalamus, • The pars nervosa contains no neuronal cell bodies.
  13. 13. Pars nervosa… • Pituicytes :  Glial cells, variable in cell size and shape.  barely visible having orange stained cytoplasm. • Herring bodies:  large unmyelinated axon terminals, containing large numbers of neurosecretory granules.  Rich capillary network present in pars nervosa
  14. 14. Thyroid gland…
  15. 15. Thyroid Gland-General Structure • It stores the inactive form of hormone extracellularly in follicles . • General Structure. Identify …  connective tissue capsule .  connective tissue septa that divide the bilobed gland into lobules .
  16. 16. follicles -of various sizes,  filled with pink-stained colloid and lined by cuboidal epithelial cells. These are the  functional units of the thyroid gland.  follicle size varies inversely with secretory activity. Interfollicular regions –  the presence of connective tissue, sinusoidal capillaries into which hormone is released)  parafollicular cells
  17. 17. Thyroid Follicles • Follicular epithelium:  vary from high cuboidal to low cuboidal ; reflects the level of follicle secretory activity.  follicle cells (principal cells) have large, centrally- or basally-located nuclei,  cells active in protein secretion.  Storage and release of thyroid hormones involves the protein thyroglobulin .
  18. 18. Parafollicular Cells  Found scattered singly or in small groups present in periphery of the follicles ,  cells are responsible for production of calcitonin, a peptide hormone that is synthesized and secreted independently of thyroid hormone.  Also called C, clear, or light cells.
  19. 19. Parafollicular Cell…  can be distinguished from follicular cells because they are large oval have eccentrically-placed nuclei and extensive, but lightly-stained cytoplasm.  They are placed in periphery of follicles
  20. 20. Thyroid gland…
  21. 21. Parathyroid Glands… General Structure :  Thin C.T. capsule that surrounds each gland and gives rise to internal septa.  glands are actually embedded in the capsule of the thyroid gland.
  22. 22. Parathyroid Glands-Parenchyma  present as a mass of crowded single cells, not arranged as follicles. It consist of 2 type of cells: Chief cells (principal cells):  Numerous ,small cells with prominent nuclei, and the pale,scant cytoplasmic staining.
  23. 23. Parathyroid Glands… Oxyphil cells:  single or clumps of larger cells with acidophilic (oxyphilic), cytoplasm with dark staining nucleus.  Number inrease with age.  Oxyphil cells are not always present in a section of parathyroid gland.
  24. 24. Adrenal gland…
  25. 25. Adrenal Glands… Like the pituitary, they are composed of two distinctly different components, one of mesothelial origin and one of neural origin . General Structure • outer cortex , and the inner medulla . These zones are readily observed even in a fresh, unstained section. • 3 histological zones of the cortex. • tough connective tissue capsule and radial trabeculae that extend into the cortex. • Prominent central vein in the medulla.
  26. 26. Adrenal Cortex… • The cortex is divided into three layers: – Zona glomerulosa – Zona fasciculata – Zona reticularis medulla capsule reticularis
  27. 27. Adrenal Cortex: Zona Glomerulosa Identify… • outermost cortical layer , and note the presence of columnar epithelial cells arranged in long cords that appear as ovoid clumps when cut in crosssection. • cytoplasm is pink and relatively scant contain lipid droplets. • capillary sinusoids are abundant.
  28. 28. Adrenal Cortex: Zona Fasciculata… • Note that this is the broadest, lightest-staining of the three cortical zones, with epithelial cells that have large, abundant, poorly-stained cytoplasm. • Cells are arranged in vertical columns of radial plates • Identify capillary sinusoids between cords of secretory cells.
  29. 29. Adrenal Cortex: Zona Reticularis… • Note that the epithelial cells of this innermost, prominently stained zone are arranged in irregular, anastomosing cords and clumps with wide capillary sinuses intervening. • Note that the secretory cells are small, with relatively darkly stained cytoplasm that may contain yellow pigment.
  30. 30. Adrenal Medulla: Chromaffin Cells • Derived from neural crest, cells of the medulla are functionally equivalent to postganglionic sympathetic neurons. • Chromaffin cells. The secretory cells of the medulla contain catecholamines (norepinephrine and epinephrine) in cytoplasmic granules that are oxidized to a brown color by potassium bichromate (the chromaffin reaction).
  31. 31. Adrenal Medulla: Chromaffin Cells Note that chromaffin cell cytoplasm is quite basophilic, compared to the acidophilia of the adjacent zona reticularis. Note that the cells are arranged into tight clumps, with wide capillaries and venous channels intervening .
  32. 32. Adrenal Medulla: Blood Supply • The medullary capillary network receives blood from a capsular plexus both indirectly, via cortical capillary sinusoids, and directly, via small arteries passing through the cortex from the capsule. • Identify the extensive network of dilated capillaries in the medulla.
  33. 33. Pineal Gland-General Structure • The pineal gland is an evagination of the diencephalon of the brain, and contains highly modified neurons called pinealocytes. General structure • Under low power, identify trabeculae that arise from pia mater. Trabeculae divide the pineal parenchyma into indistinct lobules.
  34. 34. Pineal Gland-Parenchyma • The parenchyma contains two cell types, pinealocytes and neuroglia. • The pinealocytes are modified neurons. • You will not need to distinguish these two cell types.
  35. 35. Pineal Gland-Pineal Sand • Basophilic, extracellular concretions . They are often calcified, which makes the pineal gland an excellent radiological marker, particularly of the midline.
  36. 36. Epiphysis (Pineal Gland) • The pineal is innervated by unmyelinated axons of postganglionic sympathetic neurons. This is an unusual example of a central nervous system structure that receives sympathetic innervation. • Presence of a rich vascular supply characteristic of all endocrine glands.
  37. 37. Endocrine Pancreas: Islets of Langerhans • The pancreas is a mixed exocrine and endocrine gland. General Structure • Note that islet cells are found as clumps of small secretory cells with relatively lightly-stained cytoplasm present in connective tissue . • Compare their appearance to that of the prolific protein-secreting cells of exocrine pancreatic acini . • Identify the rich network of capillaries that characterize all endocrine organs.
  38. 38. Islet of Langerhans… • Consist of 3 types of cells  Alpha cells (30%) Stains pinks present more on peripheral region  Beta cells (70%) Stains blue More in the centre  Delta cells Least in no.
  39. 39. Clinical Histology 1.Goiter (Multinodular) • common cause of overactivity of the thyroid gland (hyperthyroidism). • Increased TSH production results in the formation of characteristic large nodules . • Rx- surgical removal of part of the thyroid, or by injection of radioactive iodine 2.Graves Disease (hyperthyroid) – Follicles are very small (little colloid) – Colloid appears to have open spaces along its edge scalloped edges (common to hyperthyroidism
  40. 40. 3. Hashimoto's Thyroiditis: • Autoimmune condition in which the immune system attacks the thyroid, causing a reduction in the number and size of follicles. • Rx replacement/ admin. of thyroid hormone.
  41. 41. 4.Adrenal Atrophy: – Hypoplasia (decrease in cells) usually in the cortex but also gaps in the medulla – Proliferation of parenchymal cells 5.Adrenal Pheochromocytoma: – Benign condition where Medulla is enlarged and represents the majority of the adrenal gland – Large, bizarre looking nuclei (large and dark-staining) – Large vascular spaces
  42. 42. 5.Hyperparathyroidism (bone): – Within the bone spicules, you can see osteoclasts degrading the bone (more osteoclasts than usual) – osteoclasts are multinucleate 6.Parathyroid Oxyphil Adenoma: – Identify healthy parathyroid for its darkly staining chief cells, pink oxyphil cells, and fat throughout – Tumor is made entirely of oxyphil cells – Monoclonal proliferation= tumor composed of 1 type of cell )
  43. 43. 7.Pituitary Acidophilic Adenoma: – Tumors tend to be in the anterior pituitary; monoclonal proliferations of 1 of the 3 common anterior pituitary cells – In this case, it is an acidophilic adenoma so the cytoplasms are predominantly pink-staining – Acidophils make hormones that serve non-endocrine glands (ex. Mammary gland) 8.Type II Diabetes (pancreas): – Enlarged islets of Langerhans – Hyaline deposits in the islets (pinker than usual)
  44. 44. Thank u.

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