Thyroid gland parafollicular cells are also known as C cells, calcitonin-secreting cells, and ultimobranchial body-derived cells. They are located in the thyroid gland and are responsible for producing the hormone calcitonin. Calcitonin is a hormone that helps to regulate calcium levels in the blood.
Structure of Thyroid Gland Parafollicular Cells
Parafollicular cells, also known as C cells, are specialized cells located in the thyroid gland. They play a crucial role in calcium metabolism and hormone secretion. Here’s an in-depth look at their structure:
Histology
- Located between thyroid follicles, scattered throughout the gland
- Polygonal or round in shape
- Pale-staining cytoplasm with a central nucleus
- Characterized by numerous secretory granules
Cell Membrane
- Contains receptors for calcitonin gene-related peptide (CGRP), which stimulates hormone release
- Responds to changes in calcium levels
Cytoplasm
- Rich in mitochondria, which provide energy for hormone synthesis
- Abundant rough endoplasmic reticulum, where calcitonin is synthesized
- Golgi apparatus, responsible for packaging and secretion of calcitonin
Nucleus
- Central location
- Contains DNA and regulates gene expression
Hormone Secretion
- Parafollicular cells secrete calcitonin, a hormone that regulates calcium levels
- Calcitonin release is stimulated by high calcium levels or CGRP
- Calcitonin inhibits bone resorption and promotes calcium deposition in bone, lowering blood calcium levels
Table: Summary of Thyroid Gland Parafollicular Cell Structure
| Feature | Description |
|---|---|
| Location | Between thyroid follicles |
| Shape | Polygonal or round |
| Cytoplasm | Pale-staining, numerous secretory granules |
| Cell Membrane | Receptors for CGRP |
| Nucleus | Central location |
| Hormone | Calcitonin |
| Function | Regulates calcium metabolism |
Question 1:
What are the characteristics of parafollicular cells in the thyroid gland?
Answer:
Parafollicular cells, also known as C-cells, are specialized epithelial cells located in the thyroid gland. They are polygonal or spindle-shaped, with clear cytoplasm and a round nucleus. These cells possess Golgi complexes, mitochondria, and secretory granules containing the hormone calcitonin.
Question 2:
How do parafollicular cells contribute to calcium homeostasis?
Answer:
Parafollicular cells are responsible for the synthesis and secretion of calcitonin. Calcitonin is a hormone that acts on osteoclasts to inhibit bone resorption. By suppressing bone resorption, parafollicular cells help maintain calcium homeostasis in the body.
Question 3:
What is the clinical significance of parafollicular cell abnormalities?
Answer:
Abnormalities in parafollicular cells can lead to disorders of calcium metabolism. Hyperactivity of these cells, resulting in excessive calcitonin secretion, can cause medullary thyroid carcinoma, a rare but aggressive type of thyroid cancer. Conversely, underactivity of parafollicular cells can lead to hypocalcemia, a condition characterized by low levels of calcium in the blood.
Alrighty folks, that’s it for our deep dive into the world of thyroid gland parafollicular cells. Hopefully, you’ve learned a thing or two about these tiny but mighty cells. They might be little, but they play a big role in our health. So, next time you’re feeling a little under the weather, give a shoutout to your parafollicular cells for keeping you going. Thanks for reading, and be sure to check back soon for more science-y adventures!