Fig. 6

C. daubneyi uses atypical eggshell crosslinking chemistry. A Transmission electron micrograph of a vitelline follicle of adult C. daubneyi. Vitelline cells at various stages of maturation are present, including undifferentiated stem cells (S), early intermediate type cells (It1) in which clusters of shell precursor protein globules (P) are accumulating in the cytoplasm, later intermediate type cells (It2) within which, in addition to shell protein globules, areas of glycogen are apparent (G), and mature vitelline cells (M) with large glycogen reserves, heterophagosomes (H) and peripherally situated clusters of shell protein globules. Cytoplasmic extensions of nurse cells, containing dense mitochondria and lysosomes, envelop the vitelline cells (arrowed), to which they are connected by junctional complexes. Occasional nurse cell bodies are evident, each featuring a nucleus (Nc) with perinuclear cytoplasm. B Amino acid composition of C. daubneyi and F. hepatica whole eggs and eggshell fragments. L-DOPA, which mediates dityrosine crosslinks in trematode eggshells was not detected in C. daubneyi. Data are the means ± standard deviation of three experiments