Figure 2.

Primary cilia are observed in follicular cells of pigs (a-c), rabbits (d-e) and guinea pigs (f). Cilia are abundant in the follicular epithelium of pig and rabbit thyroid glands but are very scarce in guinea pigs (arrow). Normally, they emerged as single elements from the center of the cell apex, as observed in tangential sections of thyroid follicles (b,e). In contrast to those species, primary cilia were not detected in either rat (h) or mouse thyroid tissue (i). Ciliary tracheal epithelium from guinea pig (g) or rat (j) was used as positive control. Double immunofluorescence staining: E-cadherin (green); acetylated α-tubulin (red); blue (nuclear counterstaining with DAPI).