Answer
An osteoid seam is an unmineralized band of the bony matrix that is about 10-12 micrometers wide. Between this seam and older bone is an abrupt transition called a calcification front. The osteoid seam always stays the same width, indicating that osteoid tissue must mature before it can be calcified. This area then changes quickly from an unmineralized matrix to a mineralized matrix.
Work Step by Step
The answer can be verified on page 187 of the textbook under the "Bone Deposit" section.