Ostrovsky, Andrew Nickolaevitch, Schäfer, Priska and Gordon, Dennis Paul (2003) Ultrastructure and Development of the Ooecial Walls in Some Calloporid Bryozoans (Gymnolaemata: Cheilostomata). Zoologischer Anzeiger - A Journal of Comparative Zoology, 242 (3). pp. 223-240. DOI 10.1078/0044-5231-00100.

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Abstract

In the brood chambers (ovicells) of six calloporid cheilostomes studied each skeletal wall consists of four calcified layers: (1) a very thin superficial layer of planar spherulitic crystallites, (2) an upper (outer) layer with wall-perpendicular prismatic ultrastructure, (3) an intermediate lamellar layer, and (4) a lower (inner) wall-perpendicular prismatic layer. Comparative studies of both the ovicell wall ultrastructure and early ovicell formation showed a hypothetical opportunity for evolving complex (multilayered) skeletal walls by fusion of the initially separated gymnocystal and cryptocystal calcifications in Cheilostomata. In two species studied, a bilobate pattern in the final stage of the formation of the ooecial roof was encountered in specimens with the cuticle preserved. A possible explanation to this finding is discussed - the bilobate pattern is suggestive of the hypothetical origin of the brood chamber from (1) two flattened spines, or (2) reduction in spine number of an originally multispinous ovicell.

Document Type:	Article
Keywords:	Ovicells Callopora Tegella Crassimarginatella Bryozoa
Research affiliation:	Kiel University
Refereed:	No
Date Deposited:	02 Feb 2012 09:04
Last Modified:	09 Oct 2012 03:55
URI:	https://oceanrep.geomar.de/id/eprint/16212

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