Mechanisms of Ageing and Development 105 (1998) 45–59 Primmorphs generated from dissociated cells of the sponge Suberites domuncula : a model system for studies of cell proliferation and cell death Marcio Reis Custodio a,b , Ivo Prokic a , Renate Steffen a , Claudia Koziol a , Radovan Borojevic b , Franz Bru ¨ mmer c , Michael Nickel c , Werner E.G. Mu ¨ ller a, * a Institut fu ¨r Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Uniersita ¨t, Duesbergweg 6, Mainz, D-55099, Germany b Departamento de Histologia e Embriologia, Instituto de Cie ˆcias Biome ´dicas, Uniersidade Federal de Rio de Janeiro, Rio de Janeiro, CEP 21941 -970, CP 68021, Brazil c Biologisches Institut, Abteilung Zoologie, Uniersita ¨t, Pfaffenwaldring 57, Stuttgart, 70550, Germany Received 5 May 1998; received in revised form 19 June 1998; accepted 29 June 1998 Abstract Sponges (Porifera ) represent the lowest metazoan phylum; they have been shown to be provided with the characteristic metazoan structural and functional molecules. One autapo- morphic character of sponges is the presence of high levels of telomerase activity in all cells (or almost all cells, including somatic cells). In spite of this fact previous attempts to cultivate sponge cells remained unsuccessful. It was found that dissociated sponge cells do not replicate DNA and lose their telomerase activity. In addition, no nutrients or metabolites have been detected that would stimulate sponge cells to divide. In the present study we report the culture conditions required for the formation of multicellular aggregates from dissociated single cells of Suberites domuncula, termed primmorphs. These primmorphs are formed in seawater without addition of further supplements, and have an organised tissue-like struc- ture; they have been cultured for more than 5 months. Cross-sections revealed a distinct * Corresponding author. Tel.: +49 6131 395910; fax: +49 6131 395243; e-mail: wmueller@ mail.uni-mainz.de 0047-6374/98/$ - see front matter © 1998 Elsevier Science Ireland Ltd. All rights reserved. PII S0047-6374(98)00078-5