An improved method for whole mount embryo preparations from chick embryos.

ABSTRACT

Background: Embryology studies require good quality embryonic images. In addition, many teratology studies require the critical gross examination of embryos to determine the exact stage of embryonic development, or the extent of malformations. Objectives: The present study was designed to develop an improved method for preparing embryos. Materials and Methods: Sixty fertilized chicken eggs were divided into 6 groups of 10 and incubated at 38 oC foe various time periods (18, 20, 25, 30, 55, 72 hrs) depending on the developmental stage of the embryos. After incubation, the embryos were removed from the shells and yolk sacs. In each group, 5 embryos were stained using the Mayer’s carmine technique and the remaining 5 embryos were stained using the improved method. By the new method, the embryos were macerated in 3% potassium hydroxide for different length of time before the Mayer’s carmine staining. Results: It was found that the whole mount chick embryos which were stained with Mayer’s carmine after maceration were of better quality than those stained using the routine Mayer’s carmine technique. The new method gave superior preservation, clarity and contrast of the normal embryonic details. Interestingly, the advantage of the new method was clearly noted in the later stage of embryonic development, at the 30-somite and 30-somite stages. Using the routine Mayer’s carmine technique, the development of heart, circulation, and nervous system were not clearly differentiated, since those structures were concealed by soft tissues and/or many structures. In contrast, the new technique facilitated identification and allowed us to understand the whole development process of those structures. Conclusions: The new method improves the visibility of embryonic details normally seen or not seen with the Mayer’s carmine technique. It permits good quality photographs to be produced rapidly and consistently for the standard gross embryo analyses in embryology and teratology.