Thyroid and parathyroid glands: Histology

Summary

The video provides an in-depth overview of the thyroid and parathyroid glands. The thyroid, a butterfly-shaped endocrine gland, stores inactive hormones in follicles, with its cells responsible for producing T3 and T4 hormones. Parafollicular cells in the thyroid secrete calcitonin. The parathyroid glands, consisting mainly of chief cells and oxyphil cells, secrete parathyroid hormone (PTH). The video emphasizes the unique structure and function of these glands, highlighting their cellular composition, hormone production, and changes that occur with age, offering crucial insights for current and future clinicians.

Takeaways

• 😀 The thyroid gland is butterfly-shaped and located below the larynx, producing T3, T4, and calcitonin.
• 😀 The thyroid stores its hormones extracellularly in follicles filled with colloid, which contains thyroglobulin and thyroid hormones.
• 😀 Follicular cells of the thyroid are cuboidal and secrete thyroid hormones when needed, and their nuclei are important for diagnosing thyroid cancer.
• 😀 C cells (parafollicular cells) are responsible for secreting calcitonin and are located at the periphery of thyroid follicles.
• 😀 The parathyroid glands are small, located behind the thyroid, and secrete parathyroid hormone (PTH) to regulate calcium levels.
• 😀 Parathyroid glands consist mainly of chief cells, which secrete PTH, and oxyphil cells, which increase with age but don't secrete PTH.
• 😀 Chief cells in the parathyroid have round nuclei, pale cytoplasm, and are active in secreting PTH when their cytoplasm appears darker due to increased rough endoplasmic reticulum.
• 😀 Oxyphil cells in the parathyroid have eosinophilic cytoplasm and large mitochondria, and their numbers increase with age.
• 😀 Adipocytes (fat cells) also accumulate in the parathyroid as a person ages.
• 😀 The thyroid and parathyroid glands have distinctive features, including the unique extracellular storage of thyroid hormones and the different types of cells involved in hormone secretion.

Q & A

What is the function of the thyroid gland?

The thyroid gland produces two main hormones, T3 (triiodothyronine) and T4 (thyroxine), which contain iodine. These hormones are responsible for regulating metabolism and energy production. The thyroid also produces calcitonin, which helps regulate calcium levels in the blood.

Where is the thyroid gland located in the human body?

The thyroid gland is located anterior (in front) and inferior (below) to the larynx, just below the Adam's apple in the neck.

What is unique about how the thyroid gland stores hormones?

The thyroid gland is unique because it stores its inactive hormones extracellularly in follicles filled with colloid, which consists of thyroglobulin and thyroid hormones bound to it.

What is the role of the follicular cells in the thyroid gland?

The follicular cells in the thyroid gland are simple cuboidal cells that secrete thyroid hormones (T3 and T4) when needed. These hormones help regulate metabolism and energy balance in the body.

What is the significance of nuclear features in follicular cells for diagnosing thyroid cancer?

In papillary thyroid carcinoma, the follicular cells exhibit distinct nuclear features, such as large, irregular nuclei with light chromatin. These features are important for diagnosis, as they help differentiate the cancer from normal thyroid tissue.

What are C cells in the thyroid gland and what do they secrete?

C cells, also called parafollicular cells, are found in the thyroid gland. They are responsible for secreting calcitonin, a hormone involved in lowering blood calcium levels.

How does the parathyroid gland differ from the thyroid gland in terms of function?

The parathyroid gland produces parathyroid hormone (PTH), which regulates calcium levels in the blood by increasing calcium release from bones and reducing calcium loss through urine. In contrast, the thyroid gland mainly regulates metabolism through thyroid hormones and calcium balance through calcitonin.

What types of cells make up the parathyroid gland, and what are their functions?

The parathyroid gland consists primarily of chief cells, which secrete parathyroid hormone (PTH). There are also oxyphil cells, which are larger and eosinophilic due to increased mitochondria but do not secrete PTH. These cells increase in number with age.

What is the role of adipose tissue in the parathyroid gland?

Adipose tissue in the parathyroid gland increases with age. It does not play a direct role in hormone secretion but contributes to the overall structure of the gland.

What changes occur in the parathyroid gland with age?

With age, the parathyroid gland shows an increase in adipose tissue and a higher number of oxyphil cells. These changes can affect the overall function and hormone secretion of the gland.