Document Detail

The internal-brooding apparatus in the bryozoan genus Cauloramphus (Cheilostomata: Calloporidae) and its inferred homology to ovicells.
MedLine Citation:
PMID:  18271635     Owner:  NLM     Status:  MEDLINE    
We studied by SEM the external morphology of the ooecium in eight bryozoans of the genus Cauloramphus (Cheilostomata, Calloporidae): C. spinifer, C. variegatus, C. magnus, C. multiavicularia, C. tortilis, C. cryptoarmatus, C. niger, and C. multispinosus, and by sectioning and light microscopy the anatomy of the brooding apparatus of C. spinifer, C. cryptoarmatus, and C. niger. These species all have a brood sac, formed by invagination of the non-calcified distal body wall of the maternal zooid, located in the distal half of the maternal (egg-producing) autozooid, and a vestigial, maternally budded kenozooidal ooecium. The brood sac comprises a main chamber and a long passage (neck) opening externally independently of the introvert. The non-calcified portion of the maternal distal wall between the neck and tip of the zooidal operculum is involved in closing and opening the brood sac, and contains both musculature and a reduced sclerite that suggest homology with the ooecial vesicle of a hyperstomial ovicell. We interpret the brooding apparatus in Cauloramphus as a highly modified form of cheilostome hyperstomial ovicell, as both types share 1) a brood chamber bounded by 2) the ooecium and 3) a component of the distal wall of the maternal zooid. We discuss Cauloramphus as a hypothetical penultimate stage in ovicell reduction in calloporid bryozoans. We suggest that the internal-brooding genus Gontarella, of uncertain taxonomic affinities, is actually a calloporid and represents the ultimate stage in which no trace of the ooecium remains. Internal brooding apparently evolved several times independently within the Calloporidae.
Andrew N Ostrovsky; Matthew H Dick; Shunsuke F Mawatari
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Zoological science     Volume:  24     ISSN:  0289-0003     ISO Abbreviation:  Zool. Sci.     Publication Date:  2007 Dec 
Date Detail:
Created Date:  2008-02-14     Completed Date:  2008-06-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8702287     Medline TA:  Zoolog Sci     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  1187-96     Citation Subset:  IM    
Department of Invertebrate Zoology, Faculty of Biology & Soil Science, St. Petersburg State University, Universitetskaja nab. 7/9, St. Petersburg 199034, Russia.
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MeSH Terms
Bryozoa / anatomy & histology*,  embryology,  ultrastructure*
Embryonic Development*
Evolution, Molecular*
Microscopy, Electron, Scanning / methods,  veterinary*
Oviposition / physiology
Species Specificity

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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