Different morphotypes of functional dentition in the lower molar region of tabby (EDA) mice.

OBJECTIVES

To sort and classify the highly variable lower molar dentition in tabby (Ta) mice postnatally. The Ta syndome is homologous to the anhidrotic (hypohidrotic) ectodermal dysplasia (EDA) in human and includes severe developmental defects of teeth, hair and sweat glands.

DESIGN

Analysis of tooth shape and cusp pattern and measurement of the mesio-distal crown length.

SETTING AND SAMPLE POPULATION

Institute of Experimental Medicine, Academy of Sciences, Prague. Fixed heads of 107 tabby (Ta) homozygous and hemizygous mice and 90 wild type mice aged from post-natal day 11 to adulthood, collected during 1995-2001.

OUTCOME MEASURE

Identification of distinct morphotypes of Ta dentition. Reduced tooth length in Ta teeth and specific differences in tooth length between distinct morphotypes.

RESULTS

The variable dentitions in the lower molar region of Ta mice were classified in two basic morphotypes I and II. The morphotype I was further subdivided into particular morphotypes Ia, Ib and Ic. Proportion of the basic morphotypes I and II was different in the offspring of heterozygous (84% and 12%) compared with homozygous + hemizygous (45% and 52%) mothers. The proportions of particular morphotypes within a basic morphotype were similar in both offspring groups.

CONCLUSION

The identification of the distinct morphotypes made possible to classify the structural variability of the mandibular functional dentition in Ta mice.