Is the endoplasmic reticulum contiguous with the nuclear envelope?

The endoplasmic reticulum (ER) is indeed contiguous with the nuclear envelope. This connection is significant because the outer membrane of the nuclear envelope is an extension of the endoplasmic reticulum. This relationship allows for direct communication and transport between the nucleus and the ER, facilitating the synthesis of proteins that are either secreted from the cell, incorporated into the cell's plasma membrane, or sent to organelles.

The fact that the ER is contiguous with the nuclear envelope enhances cellular efficiency in processes such as RNA translation into proteins, as ribosomes on the rough ER can synthesize proteins immediately adjacent to the genetic material housed in the nucleus. This structural integration reflects an essential aspect of cellular organization, underscoring the interconnectedness of various organelles within eukaryotic cells.