vesicle
elevated, circumscribed, superficial, not into dermis; filled with serous fluid; less than 1 cm in diameter; examples are varicella (chickenpox), herpes zoster (shingles), impetigo, acute eczema
A vesicle is a small, membrane-bound sac or sac-like structure that plays a vital role in intracellular transport, storage, and communication in eukaryotic cells. Vesicles are formed by the inward budding of the plasma membrane or other membrane-bound organelles like the endoplasmic reticulum, Golgi apparatus, or lysosomes. They vary in size, shape, and composition, depending on their function and origin.
Some of the functions of vesicles include:
1. Transport of molecules: Vesicles transport molecules such as proteins, lipids, carbohydrates, and nucleic acids between different compartments of the cell. For instance, the Golgi complex forms vesicles that carry modified proteins to the cell membrane or lysosomes.
2. Storage of molecules: Some vesicles can store molecules within the cell, such as neurotransmitters in nerve cells.
3. Recycling cellular components: Lysosomes contain vesicles that can break down worn-out organelles or digest nutrients from the extracellular environment.
4. Secretion: Vesicles can also be used for the secretion of molecules outside of the cell, such as hormones or enzymes.
Overall, vesicles are crucial for the proper functioning of cells and the maintenance of cellular homeostasis.