Page 769 - Atlas of Histology with Functional Correlations

show retraction (1) from the follicular wall or distortion (1) as a result of

chemicals used in slide preparation.

The parafollicular cells (3, 11) (C cells) are adjacent to the follicular cells
(2, 10) or in small clumps (3) adjacent to the thyroid follicles (7). These cells (3,
11) are larger than the follicular cells (2, 10) with an oval shape and lighter-
staining cytoplasm.

Surrounding the thyroid follicles (7), the follicular cells (2, 10), and the

parafollicular cells (3, 11) (C cells) is a thin interfollicular connective tissue (9)
with numerous blood vessels (5) and capillaries (4, 8) that are very close to the
individual follicles.

FIGURE 19.10 ■ Thyroid gland follicles: canine (sectional view). Stain:
hematoxylin and eosin. High magnification.

FUNCTIONAL CORRELATIONS

19.4Thyroid Gland

Formation of Thyroid Hormones

The follicular cells that produce the thyroid hormones in the thyroid
gland are controlled by thyroid-stimulating hormone (TSH) from the
adenohypophysis. Iodide is an essential element for the production of the

active thyroid hormones triiodothyronine (T ) and tetraiodothyronine, or
3
thyroxine (T ).
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