the blank is a series of canals that forms intricate connection links between the plasma membrane and the nuclear membrane
The structure you are referring to is called the endoplasmic reticulum (ER). It is a network of tubules and flattened sacs called cisternae that extends throughout the cytoplasm of eukaryotic cells. The ER can be classified into two regions: the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER).
The RER is characterized by the presence of ribosomes attached to its surface, giving it a "rough" appearance. These ribosomes are responsible for synthesizing proteins that are destined for export or insertion into the plasma membrane. As the newly synthesized proteins are produced, they are then transported into the ER lumen, the interior space of the ER.
The SER, on the other hand, lacks ribosomes and appears smooth under a microscope. It plays various roles, including lipid metabolism, detoxification of drugs and toxins, and maintaining calcium ion storage.
Both the RER and SER are physically connected, forming an intricate network that spans the entire cell. This network allows for the exchange and transport of molecules, lipids, and ions between the different regions of the ER, the plasma membrane, and even the nuclear membrane.
To visualize the endoplasmic reticulum in cells, scientists often employ different staining techniques or use fluorescent markers that specifically bind to ER components. Microscopy techniques, such as confocal microscopy or electron microscopy, can then be used to examine and study the ER structure in detail.