The spaces in spongy bone are filled with marrow.

The spaces in spongy bone are filled with red and yellow marrow.

Step 1: Understand the structure of bone Bones are made up of two types of tissue: compact bone and spongy bone. Compact bone is the hard outer layer of the bone, while spongy bone is found inside the bone.

Step 2: Identify the type of bone in the question The question refers to spongy bone, which is found inside the bone.

Step 3: Understand the composition of spongy bone Spongy bone is not completely solid. It has small spaces within it.

Step 4: Identify what fills these spaces The spaces in spongy bone are filled with marrow. There are two types of marrow: red marrow and yellow marrow.

Step 5: Answer the question Therefore, the spaces in spongy bone are filled with red and yellow marrow.