The thyroid gland is located in the neck region. It is composed of spherical follicles filled with colloid that contains thyroglobulin and iodide. Principal cells surrounding the follicles use these materials to produce thyroid hormones like thyroxine. Between follicles are parafollicular cells that produce calcitonin. Disorders include hyperthyroidism, Graves' disease, thyroiditis, and neoplasms. The histological slide shows thyroid follicles and colloid within.

2. •located anteriorly in
cervical region, just
inferior to thyroid
cartilage; two lobes
connected by thin
isthmus
•largest purely
endocrine gland in
body
THYROID GLAND

4. The thyroid gland is composed of many
spherical hollow sacs called thyroid follicles. In
this tissue section, each follicle (A) appears as
an irregular circle of cells. The principal cells,
which surround the follicle are simple cuboidal
epithelium. These follicles are filled with
a colloid (B), which usually stains pink. The
principal cells use the thyroglobulin and iodide
stored in the colloid to produce the primary
thyroid hormones - including thyroxine.
Between these follicles are the parafollicular
cells (C) which produce calcitonin.

10. Disorders of the thyroid gland:
Hyperthyroidism
• Increased metabolic rate (thyrotoxicosis)
• Causes
– overmedication in thyroid gland failure
– increased hormone due to thyroid gland
diseases – primary
– increased hormone due to TSH - secondary

11. over reactive thyroid gland

12. Graves Disease
• 80-90% of all hyperthyroidism
• One of most common autoimmune
diseases in US
• Mostly women
• Antibody that acts like TSH
• Gland is diffusely enlarged & smooth

13. graves disease

15. Thyroiditis
• Inflammation of thyroid
• Mostly chronic
– autoimmune
• Presents as goiter

16. hasimoto thyroiditis

17. Hasimoto Thyroiditis
One of most common causes of goiter &
hypothyroidism
Antibodies that block TSH

18. Neoplasms of Thyroid Gland
• Not common
• Neoplastic masses are more likely to
– be solitary masses
– “cold”
– in younger patients
– in males
• Most are from nodular goiter

20. Outline
• Introduction
• Adrenal cortex
• Cortical hormones
• Adrenal Medulla
• Medical application.

21. Introduction
• The adrenal glands are paired organs that
lie near the superior poles of the kidneys,
embedded in adipose tissue .
• They are flattened structures with a half-
moon shape; in the human, they are about
4–6 cm long, 1–2 cm wide, and 4–6 mm
thick.

22. …………….
• Together they weigh about 8 g, but their
weight and size vary with the age and
physiological condition of the individual.
• Examination of a fresh section of adrenal
gland shows that it is formed by two
concentric layers: a yellow peripheral layer,
the adrenal cortex; and a reddish-brown
central layer, the adrenal medulla

23. ……
• The adrenal cortex and the adrenal
medulla can be considered two organs
with distinct origins, functions, and
morphological characteristics that became
united during embryonic development.
• They arise from different germ layers. The
cortex arises from the coelomic epithelium,
whereas the cells of the medulla derive
from the neural crest, from which
sympathetic ganglion cells also originate.

24. ADRENAL CORTEX AND MEDULLA

25. HISTOLOGICAL SLIDE

26. Adrenal Cortex
• The cells of the adrenal cortex , which
have the typical ultrastructure of steroid-
secreting cells, do not store their secretory
products in granules;
• rather, they synthesize and secrete steroid
hormones upon demand.

27. ……
• Steroids, being low-molecular-weight lipid-
soluble molecules, diffuse through the
plasma membrane and do not require the
specialized process of exocytosis for their
release.

28. ……
• Because of the differences in disposition
and appearance of its cells, the adrenal
cortex can be subdivided into three
concentric layers whose limits are usually
not sharply defined in humans :
• the zona glomerulosa, the zona
fasciculata, and the zona reticularis.
• These layers occupy 15%, 65%, and 7%,
respectively, of the total volume of the
adrenal glands.

29. LAYERS OF ADRENAL CORTEX

30. ……
• The layer immediately beneath the
connective tissue capsule is the zona
glomerulosa, in which columnar or
pyramidal cells are arranged in closely
packed, rounded, or arched cords
surrounded by capillaries

32. ……
• The next layer of cells is known as the
zona fasciculata because of the
arrangement of the cells in one- or two-cell
thick straight cords that run at right angles
to the surface of the organ and have
capillaries between them .
• The cells of the zona fasciculata are
polyhedral, with a great number of lipid
droplets in their cytoplasm.

33. ……
• As a result of the dissolution of the lipids
during tissue preparation, the fasciculata
cells appear vacuolated in common
histological preparations.
• Because of their vacuolization, the cells of
the fasciculata are also called
spongyocytes

34. ADRENAL GLAND [H AND E ]

35. ……
• The zona reticularis , the innermost layer of
the cortex, lies between the zona fasciculata
and the medulla; it contains cells disposed in
irregular cords that form an anastomosing
network.
• These cells are smaller than those of the
other two layers.
• Lipofuscin pigment granules in the cells are
large and quite numerous. Irregularly shaped
cells with pyknotic nuclei—suggesting cell
death—are often found in this layer.

36. MEDICAL APPLICATION
• Because of the feedback mechanism of
adrenal cortex control, patients who are
treated with corticoids for long periods
should never stop taking these hormones
suddenly:
• secretion of ACTH in these patients is
inhibited, and thus the cortex will not be
induced to produce corticoids, causing a
severe misbalance in the levels of sodium
and potassium.

37. Adrenal Medulla
• The adrenal medulla is composed of
polyhedral cells arranged in cords or
clumps and supported by a reticular fiber
network.
• A profuse capillary supply intervenes
between adjacent cords, and there are a
few parasympathetic ganglion cells.

38. ……
• The medullary cells arise from neural crest
cells, as do the postganglionic neurons of
sympathetic and parasympathetic ganglia.
• Thus, the cells of the adrenal medulla can
be considered modified sympathetic
postganglionic neurons that have lost their
axons and dendrites during embryonic
development and have become secretory
cells.

40. ……
• Medullary cells have abundant membrane-
limited electron-dense secretory granules,
150–350 nm in diameter.
• These granules contain one or the other of
the catecholamines, epinephrine or
norepinephrine.
• The secretory granules also contain
adenosine triphosphate (ATP), proteins
called chromogranins (which may serve
as binding proteins for catecholamines),

41. ……
• dopamine -hydroxylase (which converts
dopamine to norepinephrine), and
opiatelike peptides (enkephalins)

42. …….
• A large body of evidence shows that
epinephrine and norepinephrine are
secreted by two different types of cells in
the medulla.
• When observed with the transmission
electron microscope epinephrine-secreting
cells show smaller and less electron-
dense granules, whose contents fill the
granule.

43. • Norepinephrine-secreting cells have larger,
more electron-dense granules. Their
content is irregular in shape, and there is
an electron-lucent layer beneath the
surrounding membrane. About 80% of the
catecholamine output of the adrenal vein
is epinephrine.

44. ……
• Unlike the cortex, which does not store
steroids, cells of the medulla accumulate
and store their hormones in granules.
• The adrenal medullary cells are innervated
by cholinergic endings of preganglionic
sympathetic neurons.
• Glucocorticoids produced in the cortex,
which reach the medulla through
capillaries that bathe cells of the cortex,
constitute another mechanism of control.

45. DISORDERS OF ADRENAL GLAND
Addison disease
• (or Addison's disease) is adrenocortical
insufficiency due to the destruction or
dysfunction of the entire adrenal cortex. It
affects glucocorticoid and
mineralocorticoid function. The onset of
disease usually occurs when 90% or more
of both adrenal cortices are dysfunctional
or destroyed.

46. cushing syndrome

47. SOME OTHER DISEASES

48. MEDICAL APPLICATION
• Epinephrine and norepinephrine are
secreted in large quantities in response to
intense emotional reactions, such as fright,
that are part of an alarm reaction (the
fight-or-flight response).
• Secretion of these substances is mediated
by the preganglionic fibers that innervate
medullary cells.

49. MEDICAL APPLICATION
• Vasoconstriction, hypertension, changes in
heart rate, and metabolic effects such as
elevated blood glucose result from the
secretion and release of catecholamines
into the bloodstream.
• During normal activity, the medulla
continuously secretes small quantities of
these hormones.

50. ……
• Medullary cells are also found in the
paraganglia (collections of catecholamine-
secreting cells adjacent to the autonomic
ganglia) as well as in various viscera.
• Paraganglia are, thus, a diffuse source of
catecholamines.

51. Draw

52. thyroid gland

54. HISTOLOGICAL SLIDE