At 100x this large bronchiole can be distinguished from larger passageways by its lack of cartilage, and by the simple ciliated columnar epithelium, with its single layer of nuclei. The thin-walled structures surrounding the bronchiole are the alveolar sacs.  Blood vessels such as this arteriole can be seen as well Note also the dark carbon particles which have collected in the lung, and the infusion of lymphocytes, part of the MALT (Mucosa Associateed Lymph Tissue) found in the lungs.