166 JOURNAL OF COSMETIC SCIENCE Figure 4. Guinea pig epidermis. Group IV (gel + glycolic acid). Figure 5. Guinea pig epidermis. Group V (gel + vitamin A + glycolic acid).

VITAMIN A AND GLYCOLIC ACID FORMULATIONS 167 Table I Mean Karyometric Values of Cells of the Basal Epidermal Layer of Control Guinea Pigs and of Guinea Pigs Topically Treated With Cosmetic Preparations (Mann-Whitney test) Groups Parameter Control T n T m T•v T v Larger diameter (prn) 6.88 9.18' 7.82** 8.68* 8.38* Smaller diameter (pm) 4.79 5.96* 5.52* 5.84* 5.28* Mean geometric diameter (pm) 5.72 7.37* 6.55* 7.09* 6.62* D/d ratio 1.46 1.57' 1.43 ns 1.51 ns 1.61' Volume (pm 3) 101.88 215.71' 151.13' 192.74' 155.83' Area (pm 2) 26.03 43.08* 33.99* 39.91' 34.74* V/A ratio 3.81 4.91' 4.36* 4.73* 4.42* Perimeter (pm) 18.50 24.09* 21.13* 23.06* 21.79' Eccentricity 0.70 0.74 '•s 0.69 '•s 0.71 " 0.75* Form coefficient 0.94 0.93 '•s 0.95 n• 0.94 ns 0.92* Outline index 3.65 3.69** 3.64 n• 3.67 ns 3.71' * p 0.01 **p 0.05 ns, Nonsignificant. Table II Mean Karyometric Values of the Spinous Layer Cells of the Epidermis of Control Guinea Pigs and of Guinea Pigs Topically Treated With Cosmetic Preparations (Mann-Whitney test) Groups Parameter Control T n T m T•v T v Larger diameter (prn) 6.78 9.18* 7.94'* 8.23' 7.21' Smaller diameter (Fro) 4.50 6.10* 5.50* 5.87' 5.68' Mean geometric diameter (Fro) 5.55 7.46* 6.59* 6.93* 6.68* D/d ratio 1.51 1.5 3 ns 1.46 • 1.42'* 1.41 ** Volume (pm 3) 90.95 222.62* 153.13' 178.93' 161.52' Area (pm 2) 24.33 44.05* 34.35* 38.05* 34.46* V/A ratio 3.69 4.97* 4.39* 4.62* 4.45' Perimeter (Fro) 17.81 24.31' 21.333' 22.34* 21.54' Eccentricity 0.73 0.72 ns 0.69** 0.67* 0.66* Form coefficient 0.96 0.94 n• 0.95 • 0.95 n• 0.95 ns Outline index 3.63 3.68 ns 3.65 n• 3.64 n• 3.64 n• *p 0.01 **p 0.05 ns, Nonsignificant. STEREOLOGIC RESULTS The basal layer was stereologically thicker in the areas treated with the formulations, and this was more evident in the presence of glycolic acid. Although thicker, the basal layer presented a smaller number of cells. This increase was compared on the basis of increased cytoplasmic and cellular volumes (Table III). The same was observed with respect to the spinous layer (Table III). When the epidermis was considered as a whole, there was increased thickening, espe- cially after the use of glycolic acid. This increased thickening was also reflected on the decreased surface density. The number of cells per mm 3 was decreased (Table III). The horny layer was not evaluated quantitatively because of the trauma cased by shaving.