Morphological study of the connective tissue papillae and the capillary loops on the lingual dorsum in the type 2 diabetes mellitus model rats.

We performed a morphological study in type 2 diabetes mellitus (DM) model rats by focusing on the connective tissue papillae (CTPe) and capillary loops (CLs) of filiform papillae in the lingual dorsum in the type 2 DM model rats (GK rats). The normal group comprised nine 8-week-old male Wistar rats. The DM group comprised nine 8-week-old male GK rats. Image analysis of light microscopic specimens in CTPe was performed (height and cross-sectional area). Image analysis of scanning electron microscopic specimens (acrylic plastic injection method) in CLs was performed (number, thickness, height, interval between the tops of the two CLs, and crossing ratio between ascending and descending crura (CRC)). We compared these values between both groups (Student's t test). The former analysis revealed that the height and cross-sectional area of CTPe were smaller in the DM group than in the normal group. The latter analysis revealed that the thickness, height, and CRC of the CLs were smaller in the DM group than in the normal group. However, no significant differences were detected in the number and interval of CLs between both groups. Therefore, we concluded that DM caused regressive change in CTPe and CLs.