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Fig. 2.49 Structure and development of bilobate cleithral ovicell
in Thalamoporella sp. ( A ) Part of non-cleaned colony. ( B ) General
view of two ovicells. ( C ) Basal view of zooidal orifice and paired
communication openings (shown by arrows ) of ooecium ( arrowhead indicates medial suture). ( D ) Developing ooecia at colony
periphery. ( E ) Fractured ooecium ( arrow indicates medial suture
corresponding to longitudinal septum between bases of ooecial
lobes). ( F ) Ooecium with fractured ectooecium showing entooecium (longitudinal septum absent, medial suture of ectooecium
arrowed ). Abbreviations: cr cryptocyst, ес ectooecium, en entooecium, оe ooecium, op operculum, tw transverse wall. Scale bars:
A – F , 100 μm
Figures