Final answer:
Avascular is the term used to indicate that some cells and tissues lack blood vessels. This is particularly true for epithelial tissues, which rely on diffusion or absorption for nutrients due to the absence of a direct blood supply.
Step-by-step explanation:
The term that means some cells and tissues lack blood vessels is avascular. Epithelial tissues are a prime example of avascular tissues, where no blood vessels cross the basement membrane to enter the tissue. These tissues must acquire nutrients by diffusion or absorption from underlying tissues or the surface. This characteristic allows epithelial tissues to rapidly renew and replace damaged and dead cells, which is vital for the protection and function of our airways and digestive tracts. Avascular tissues contrast with vascular tissues, which have an extensive network of blood vessels, facilitating the delivery and removal of substances.