Parathyroid

PARATHYROID GLAND

PARATHYROID GLAND

• Four small glands

• Located behind the thyroid gland, one at each end of the upper and lower poles

• Can also be found in the mediastinum lying beside the thymus

• Usually embedded in the thyroid capsule

• Derived from the pharyngeal pouches

PARATHYROID GLANDS

• Contained within connective capsuleCapsules send septa into gland, merge with

reticular fibers that support secretory cells

• Consists of 2 cell typesChief CellsOxyphil Cells

PARATHYROID GLAND

TYPE OF CELLS

• Chief cells

• Oxyphil Cells

CHIEF CELLS

• Small polygonal cells with round nuclei

• Arranged in cords presenting whorl – like appearance

• Cytoplasm is filled with irregularly shaped granules

• Occasionally occur as clusters

• Synthesis and secretion of parathyroid hormone (parathormone)

CHIEF CELLS

RED - Chief Cells

OXYPHIL CELLS

• “Hürthle cells”

• Larger than chief cells

• Found singly or in small groups

• Less numerous than chief cells

OXYPHIL CELLS

RED – Oxyphil cells

PARATHYROID HORMONE

• Increases blood calciumIncreasing bone resorptionDecreasing renal excretionIncrease gastrointestinal uptake of calcium

Stimulating Vitamin D

Reduces blood phosphate

PARATHYROID PRINCIPAL CELLS

PARATHYROID PRINCIPAL CELLS