title: Characterization of calcium carbonate crystals in pigeon yolk sacs with different incubation times.
abstract: Calcium carbonate crystals are known to form in the yolk sacs of fertile pigeon eggs at late stages of incubation. The composition and structure of these crystals were investigated, the crystallization environment was inspected, and the physical chemistry constants of the yolk fluid were determined through the incubation period. Polarized light microscopy was used to observe the generation and distribution of calcium carbonate crystals in the yolk sac. In addition, X-ray diffraction was employed to analyze the composition and crystal phase of the yolk sac. A decalcification and deproteination method was established to analyze the ultrastructure and composition of the crystals, as well as the internal relationship between inorganic and organic phases of the crystals. Additionally, scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, and Fourier transform infrared spectroscopy were used to evaluate the characteristics of the crystals. Our results demonstrated that the calcium carbonate crystals were mainly composed of vaterite and calcite, with vaterite being the major component. Vaterite, a type of biomaterial generated by an organic template control, presented as a concentric hierarchical spherical structure. The organic nature of the biomaterial prevented vaterite from transforming into calcite, which is more thermodynamically stable than vaterite. Additionally, the configuration, size, and aggregation of vaterite were also mediated by the organic template. This bio-vaterite was found during the incubation period and is valuable in calcium transport during embryonic development.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Wuhan University), Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China; Analytical and Testing Center, Hubei University of Technology, Wuhan 430068, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Song
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Wuhan University), Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Cheng
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Wuhan University), Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Shen
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Wuhan University), Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Jingxiao
authors.initials: J
authors.lastname: Hu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Wuhan University), Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China. Electronic address: huatong09@126.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Tong
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000032:analysis*; D010856:Columbidae; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008859:Microscopy, Polarization; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction; D015017:Yolk Sac / Q000737:chemistry*
chemical_list: D002119:Calcium Carbonate
keywords: Biomineralization; Calcium carbonate; Pigeon; Vaterite; Yolk sac