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The Influence of Hen Aging on Eggshell Ultrastructure and Shell Mineral Components
Korean J. Food Sci. An. 2018;38:1080-1091
Published online October 31, 2018;
© 2018 Korean Society for Food Science of Animal Resources

Ji-Ae Park and Sea-Hwan Sohn*

Department of Animal Science and Biotechnology, Gyeongnam National University of Science and Technology, Jinju 52725, Korea
Correspondence to: Sea-Hwan Sohn
Department of Animal Science and Biotechnology, Gyeongnam National University of Science and Technology, Jinju 52725, Korea
Tel: +82-55-751-3264
Fax: +82-55-761-8308
Received August 17, 2018; Revised September 10, 2018; Accepted September 10, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The eggshell, which is a complex and highly ordered structure, is very important factor for food safety and egg marketing. This study investigated the changes in eggshell structure and shell components in relationship to hen age. For this study, we examined the histological change of the endometrium of the 30-, 60-, and 72-wk-old commercial layers, and analyzed the ultrastructure and ionic composition of their eggshells. The results showed that histological deformation, fibrosis, atrophy and elimination of micro-villi in the uterus endometrium were found through microscopic observation that was associated with increasing hen age. Concentration of blood-ion components such as Ca2+, Na+, K+, and Cl ions did not change with age. Along with the results from the ultrastructure analysis of the eggshell, the palisade layer ratio and the density of mammillary knobs were significantly decreased in older hens. In addition, the type B mammillary knobs were frequently observed with increasing hen age. In the mineral element assay from the eggshell, Ca2+, S2– , and Co2+ significantly decreased with increasing hen age, whereas Na+, K+, and V2+ significantly increased. Therefore, the damages of endometrial tissue inhibit the processes of ion transmission and the crystallization of eggshell formation, resulting in a large and non-uniform mammillary knob formation. This means the conditions of endometrial cells affect the formation of the eggshell structure. In conclusion, hen aging causes the weakness of the eggshell and degrades the eggshell quality.
Keywords : aging, eggshell ultrastructure, eggshell components ions, chicken

October 2018, 38 (5)