Here's a breakdown:

1. Endoplasmic Reticulum (ER): Lysosomal enzymes are initially synthesized on ribosomes attached to the ER.

2. Transport to Golgi: The newly synthesized enzymes are transported to the Golgi apparatus in vesicles.

3. Golgi Modification: Within the Golgi, the enzymes undergo modifications, including glycosylation (addition of sugars), which are essential for their proper function.

4. Lysosome Formation: The Golgi packages these modified enzymes into small vesicles, which bud off and mature into lysosomes.

So, while the building blocks of lysosomes (enzymes) originate in the ER, the final assembly and packaging of these enzymes into functional lysosomes takes place in the Golgi apparatus.