The worm-like cell structure derived from chromatin during reproduction is called a chromosome.

Here's why:

* Chromatin: Chromatin is the material that makes up chromosomes. It's a complex of DNA and proteins found in the nucleus of eukaryotic cells.

* Reproduction: During reproduction, the cell's genetic material (DNA) needs to be accurately copied and passed on to the offspring.

* Chromosomes: Chromatin condenses and becomes tightly packed into visible, thread-like structures called chromosomes. These chromosomes are essential for ensuring the accurate distribution of genetic material during cell division (both mitosis and meiosis).

So, while the term "worm-like" is a bit informal, it accurately describes the appearance of chromosomes when viewed under a microscope.