Picture from Olson SK et al. (2012) J Cell Biol "Hierarchical assembly of the eggshell and permeability barrier in C. ...."

(C) CPG-1 and CPG-2 are secreted CPGs composed of a protein core (blue) with covalently linked chondroitin side chains (thin black lines are putative chondroitin attachment sites based on sequence consensus; Olson et al., 2006) and chitin-binding domains. Images are electron micrographs of eggshells after immunogold labeling (10-nm beads) using antibodies recognizing both CPG-1 and CPG-2 (top) or specifically CPG-2 (bottom). Bars, 100 nm.

Picture from Olson SK et al. (2012) J Cell Biol "Hierarchical assembly of the eggshell and permeability barrier in C. ...."

Figure 1. Chitin and the CPG-1/2 localize to the middle and inner layers of the trilaminar eggshell, respectively. (middle) Transmission electron micrographs of the eggshell in high-pressure frozen embryos. (right) Pseudocolored micrographs illustrate the location of the outer (black), middle, and inner eggshell layers. Beneath the inner layer is the perivitelline space between the eggshell and embryo plasma membrane. (A, left) A schematic is provided for orientation, with the black box highlighting the imaged region. (B) Chitin is composed of repeating units of beta 1,4-linked N-acetylglucosamine. Image is an electron micrograph of an eggshell after immunogold labeling (10-nm gold beads) with a chitin-binding probe. (C) CPG-1 and CPG-2 are secreted CPGs composed of a protein core (blue) with covalently linked chondroitin side chains (thin black lines are putative chondroitin attachment sites based on sequence consensus; Olson et al., 2006) and chitin-binding domains. Images are electron micrographs of eggshells after immunogold labeling (10-nm beads) using antibodies recognizing both CPG-1 and CPG-2 (top) or specifically CPG-2 (bottom). Bars, 100 nm.