Which of the following describes continuous capillaries?

Continuous capillaries are characterized by their uninterrupted endothelial lining, which consists of tightly joined cells. This structural feature results in a highly selective barrier that restricts the passage of molecules, allowing only small ions and some small water-soluble molecules to diffuse through the endothelial cells. This makes them essential in tissues where a blood-tissue barrier is needed, such as in muscle and brain tissues.

In contrast, other types of capillaries, like fenestrated and sinusoidal capillaries, contain pores or gaps that allow larger molecules and even cells to pass through more freely. Therefore, the continuous nature of the endothelial lining in continuous capillaries is critical for maintaining specific functions in various tissues while controlling the exchange of materials. This structural attribute underlies why they are referred to as "continuous."