Figure 3From: Exogenous estradiol improves shell strength in laying hens at the end of the laying periodLocalization of carbonic anhydrase (CA) activity in duodenum shown as black staining. Laying hens Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) treated with estradiol 3-benzoate or a placebo pellet at the end of the laying period. (a) Duodenum of 72-week-old LB hen treated with placebo pellet. Strong membrane-bound staining for CA activity in the lateral cell membranes and brush border of surface epithelium. Capillaries with intense membrane-bound staining in lamina propria, crypt region and muscularis. In the crypts of Lieberkühn membrane-bound staining is moderate to strong. Bar = 160 μm. (b) Higher magnification of the same treatment with moderate to strong membrane-bound staining in the crypts of Lieberkühn. Bar = 50 μm. (c) Duodenum of LB hen treated with estradiol pellet, with weak or almost absent membrane-bound staining in crypts of Lieberkühn. Bar = 50 μm. (d) Intensity scoring of carbonic anhydrase (CA) activity in duodenum. Score 1: weak or absent staining, score 2: intermediate staining, score 3: strong staining. Results are expressed as mean ± SE. **(P < 0.01).Back to article page