THYROID
GLAND
Thyroid gland consists of large numbers of follicles filled
with a proteinous secretory substance called colloid. The follicle is lined by
single layer of cuboidal epithelial cells which becomes flattened in inactivate
state and become tall columnar in active state.
Major constituent of colloid is thyroglobulin which contains
the thyroid hormones within its molecules. It also contain mono-iodotyrosin ,
di-iodotyrosin, tri- iodotyrosin.
The thyroid gland has a blood flow about five times the
weight of the gland each minute, which is a blood supply as rich as that of any
other area of the body, with the possible exception of the adrenal cortex.
The thyroid gland begins to function from the midterm of
fetal life. Food , iodine deficiency in
the mother diet may lead to hypo function of the thyroid in the fetus and its
consequent hazards.