Figure 2

(A) The extent of X - zone vacuolation was evaluated semi - quantitatively or qualitatively based on the following four - grade system. “Grade 0” indicates that the X-zone contained only non-vacuolated cells; this corresponds to the X-zone morphology of the parental B6 (−A^y) strain. The layer of vacuolated cells in the X-zone of “Grade 3” was thickest among the grades; this corresponds to the X-zone morphology in the parental DDD (−A^y) strain. The layers of vacuolated cells in an X-zone of “Grade 1” and “Grade 2” were thinner than that of “Grade 3” The layer of vacuolated cells in an X-zone of “Grade 2” was apparently thicker than that in an X-zone of “Grade 1” (B) Histograms showing the grade distributions for F₂ non-A^y and F₂A^y mice. The mean ± S.E. grades for F₂ non-A^y and F₂A^y mice were 1.92 ± 0.09 and 2.05 ± 0.09, respectively. There was no significant difference between these two F₂ types. The number of mice with grade 0 (absence of vacuolation) was 16 (10.8%) in F₂ non-A^y and 24 (16.0%) in F₂A^y mice.