| The innermost layer adjacent to the lumen was occasionally difficult to distinguish. |
| In the lumen of the cysts, eosinophilic or blue secretions were frequently seen, with sometimes targetoid secretion. |
| The tumors located centrally were polypoid, protruding into the lumen of the bronchus and narrowing the lumen. |
| The lumen or cell chain is not always clearly visible within all filaments, especially within densely granulated sheaths. |
| Four tunnels off the lumen of the proventriculus of the carpenter bee, Xylocopa virginica virginica, have been discovered. |
| In particular, the latter and their major branches were cross-sectioned at 3-mm intervals, with no gross evidence of lesion or lumen reduction. |
