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Parafollicular cell

Parafollicular cell is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Parafollicular cell rather than just read about it. In short: Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin.

Parafollicular cell — main illustration
Parafollicular cell — illustration

Key takeaways

  • Parafollicular cell belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Parafollicular cell to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Parafollicular cell from memory before moving on to harder problems.

Reference excerpt

Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin. They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells. In birds and teleost fishes these cells occupy a structure outside the thyroid gland named the ultimopharyngeal body.

Structure Parafollicular cells are pale-staining cells found in small number in the thyroid and are typically situated basally in the epithelium, without direct contact with the follicular lumen. They are always situated within the basement membrane, which surrounds the entire follicle.

Development Parafollicular cells are derived from pharyngeal endoderm. Embryologically, they associate with the ultimopharyngeal body, which is a ventral derivative of the fourth (or fifth) pharyngeal pouch. Parafollicular cells were previously believed to be derived from the neural crest based on a series of experiments in quail-chick chimeras. However, lineage tracing experiments in mice revealed that parafollicular cells are derived from the endoderm origin.

Function Parafollicular cells secrete calcitonin, a hormone that participates in the regulation of calcium metabolism. Calcitonin lowers blood levels of calcium by inhibiting the resorption of bone by osteoclasts, and its secretion is increased proportionally with the concentration of calcium. Parafollicular cells are also known to secrete in smaller quantities several neuroendocrine peptides such as serotonin, somatostatin or CGRP. They may also have a role in regulating thyroid hormones production locally, as they express thyrotropin-releasing hormone.

Clinical significance When parafollicular cells become cancerous, they lead to medullary carcinoma of the thyroid.

See also List of human cell types derived from the germ layers List of distinct cell types in the adult human body

References

Further reading

External links Histology image: 42_04 at the University of Oklahoma Health Sciences Center Histology image: 14302loa – Histology Learning System at Boston University Histology at KUMC endo-/endo10 Anatomy Atlases – Microscopic Anatomy, plate 15.287

Illustrations

Parafollicular cell illustration

Worked examples

Example 1 — a first encounter with Parafollicular cell

Start with the simplest possible case. Write down what Parafollicular cell claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Parafollicular cell before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Parafollicular cell ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Parafollicular cell

In research
Parafollicular cell appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Parafollicular cell in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Parafollicular cell is common in secondary-school and first-year university syllabi. It links to neighbouring topics Endocrine system anatomy, Human cells, Peptide hormone secreting cells, so understanding it makes those chapters shorter.
In everyday life
Look for Parafollicular cell outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Parafollicular cell in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Parafollicular cell means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Parafollicular cell out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parafollicular cell in simple terms?

Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin.

Why does Parafollicular cell matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Parafollicular cell?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Parafollicular cell.

Tags

  • Endocrine system anatomy
  • Human cells
  • Peptide hormone secreting cells
  • Thyroid

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