Two types of shell globule clusters can be observed in the cytoplasm
of vitelline cells: shell globule clusters consisting of loosely packed
dense globules embedded in electron-lucent matrix and shell globule
clusters consisting of tightly packed dense shell globules in a matrix of
moderate density. Our observations show that the globule clusters in
D. latum are loosely packed and embedded in electron lucent matrix.
In addition to D. latum and the most basal cestodes, i.e. amphilinideans
and gyrocotylideans, such arrangement of shell globules is
present in some members of basal eucestodes, i.e., Spathebothriidea,
Caryophyllidea and Bothriocephalidea. In contrast,
tightly packed electron dense globules embedded in a matrix of moderate
density have been illustrated in three other caryophyllideans studied
. This character is also visualized in two spathebothriideans
studied. Both types of clusters are reported in Atractolytocestus
huronensis, a caryophyllidean cestode with parthenogenetic type
of reproduction. Moreover, variations in the number, size and arrangement of shell globules within the clusters have been
observed.