Ultrasonography as a tool for monitoring in ovo chicken development. 1. Technique and morphological findings

Preliminary studies were performed to develop a method for using real-time, B-mode ultrasonography (US) to directly image the internal morphology of the chicken egg and developing embryo. Different soft tissue interfaces will reflect US waves differentially. These reflected waves, or echoes are then converted into a two-dimensional image of internal morphology. A major limitation of diagnostic US is its inability to penetrate through gas or hard tissue (bone, shell) interfaces. Methodology development to overcome the acoustic obstacle presented by the eggshell and air cell constituted the initial part of the preliminary study. An acoustical window was achieved by creating a 2-cm fenestration through the large end of the eggshell, then filling the air cell with sterile saline. Morphological features of the yolk and embryo were recorded at 0, 2, 6, 9, 14, and 17 days of incubation. The second part of the preliminary study explores whether the acoustic window, once created, could then be closed, and if closed, whether egg viability could be maintained. A second concurrent trial was conducted with 32 eggs that were fenestrated, imaged, recorded, reclosed, and incubated. Two methods of closure were attempted: one using dialysis membrane and tape; the other using an eggshell allograft. Hatchability was partially retained with both window closure methods.