The microscopic bodies that carry genes and convey hereditary characteristics are called chromosomes.

Here's a breakdown:

* Genes: Segments of DNA that contain the instructions for building and maintaining an organism.

* Chromosomes: Structures made of tightly coiled DNA and proteins that contain many genes. They are found in the nucleus of cells.

* Hereditary characteristics: Traits passed down from parents to offspring.

So, chromosomes are the vehicles that carry the genetic blueprints (genes) responsible for transmitting hereditary characteristics from one generation to the next.