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Lamellar bodies

Lamellar bodies 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 Lamellar bodies rather than just read about it. In short: In cell biology, lamellar bodies (otherwise known as lamellar granules, membrane-coating granules (MCGs), keratinosomes or Odland bodies) are secretory organelles found in type II alveolar cells in the lungs, and in keratinocytes in the skin. They are oblong structures, appearing about 300-400 nm in width and 100-150 nm in length in transmission electron microscopy images.

Lamellar bodies — main illustration
Lamellar bodies — illustration

Key takeaways

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

Reference excerpt

In cell biology, lamellar bodies (otherwise known as lamellar granules, membrane-coating granules (MCGs), keratinosomes or Odland bodies) are secretory organelles found in type II alveolar cells in the lungs, and in keratinocytes in the skin. They are oblong structures, appearing about 300-400 nm in width and 100-150 nm in length in transmission electron microscopy images. Lamellar bodies in the alveoli of the lungs fuse with the cell membrane and release pulmonary surfactant into the extracellular space.

Role in lungs In alveolar cells the phosphatidylcholines (choline-based phospholipids) that are stored in the lamellar bodies serve as pulmonary surfactant after being released from the cell. In 1964, using transmission electron microscopy, which at that time was a relatively new tool for ultrastructural elucidation, John Balis identified the presence of lamellar bodies in type II alveolar cells, and further noted that upon their exocytotic migration to the alveolar surface, lamellar contents would uniformly unravel and spread along the circumference of the alveolus, thus lowering surface tension and similarly, the required alveolar inflation force.

Role in epidermis In the upper stratum spinosum and stratum granulosum layers of the epidermis, lamellar bodies are secreted from keratinocytes, resulting in the formation of an impermeable, lipid-containing membrane that serves as a water barrier and is required for correct skin barrier function. These bodies release components that are required for skin shedding (desquamation) in the uppermost epidermal layer, the stratum corneum. These components include lipids (e.g. glucosylceramides), hydrolytic enzymes (e.g. proteases, acid phosphatases, glucosidases, lipases) and proteins (e.g. corneodesmosin). Lamellar bodies have been observed to contain distinct aggregates of the secreted components glucosylceramide, cathepsin D, KLK7, KLK8 and corneodesmosin. Transportation of molecules via lamellar bodies is thought to prevent enzymes from interacting with their relevant substrates or inhibitors prior to secretion. Recent work suggests that lamellar bodies form a continuous membranous structure with the trans-Golgi network. Lamellar body secretion and lipid structure is abnormal in the epidermis of patients with Netherton syndrome, a skin disorder characterised by chronic inflammation and universal pruritus (itch). Deficient lipid membrane causes cold damage in patients of asteatotic eczema (also known as winter eczema).

See also Lecithin–sphingomyelin ratio

References

External links Dr. Jastrow's Electron microscopic atlas Archived 2017-12-07 at the Wayback Machine EM at meddean.luc.edu

Illustrations

Lamellar bodies: Red arrows indicate secreted lamellar bodies, and green arrows indicate lamellar bodies in the cytoplasm. Scale bar = 200 nm.
Red arrows indicate secreted lamellar bodies, and green arrows indicate lamellar bodies in the cytoplasm. Scale bar = 200 nm.

Worked examples

Example 1 — a first encounter with Lamellar bodies

Start with the simplest possible case. Write down what Lamellar bodies 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 Lamellar bodies 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 Lamellar bodies 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 Lamellar bodies

In research
Lamellar bodies 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 Lamellar bodies 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
Lamellar bodies is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cell anatomy, Lung anatomy, Organelles, so understanding it makes those chapters shorter.
In everyday life
Look for Lamellar bodies 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 Lamellar bodies in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Lamellar bodies 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 Lamellar bodies out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lamellar bodies in simple terms?

In cell biology, lamellar bodies (otherwise known as lamellar granules, membrane-coating granules (MCGs), keratinosomes or Odland bodies) are secretory organelles found in type II alveolar cells in the lungs, and in keratinocytes in the skin. They are oblong structures, appearing about 300-400 nm i…

Why does Lamellar bodies 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 Lamellar bodies?

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 Lamellar bodies.

Tags

  • Cell anatomy
  • Lung anatomy
  • Organelles
  • Skin anatomy

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