Poorly differentiated mesenchymal cells produce the connective tissue matrix (collagen and elastic fibers, ground substance). In the image, the cell seems to be a typical cell with protein-synthesizing machinery. One may find its main components: a large nucleus, with a prominent nucleolus and some active euchromatin, the cytoplasm with a highly developed rough endoplasmic reticulum (RER), whose cisterns contain synthesized products; and mitochondria #1, #2. The RER is connected with the perinuclear space. The cellular cytoplasm is demarcated from the extracellular environment by a cell membrane (plasma membrane). Heterochromatin is a type of chromatin that is inactive (not under transcription) at the moment.