Abstract:
:Freshwater sponges of the family Spongillidae reproduce sexually through formation of a parenchymula larva. The cytochemical characteristics of parenchymula larval metamorphosis - beginning with the blastula and terminating with the motile escape stage - for the spongillid Eunapius fragilis (Leidy) have been defined using both absorption and fluorescent cytochemical methods, particularly those demonstrating protein end-groups. Morphogenesis of the parenchymula larva of E. fragilis involves the interrelated processes of cytodifferentiation and mobilization of reserve materials. Larval development has been categorized into five stages, from blastula (stage I) through the escape stage (stage V). Parenchymula development is characterized by morphogenetic precocity, a fact influencing the rate of mobilization of cytoplasmic reserves, cytodifferentiation, and the fate of individual cell types. With attainment of the stage V parenchymula, the larva is, essentially, a mobile adult sponge exhibiting flagellated chambers, canal systems, a well defined connective tissue stroma, a diverse cell population consisting of specialized elements and a totipotent archeocyte reserve, and a terminal epitheliocyte line. The present study recognizes differences in development within the spongillids as well as within more remote poriferan taxa - emphasizing the need for detiled understanding of particular processes in individual species before proposing major generalizations about development in this ancient but evolutionally specialized group.
journal_name
J Morpholjournal_title
Journal of morphologyauthors
Harrison FW,Cowden RRdoi
10.1002/jmor.1051450202subject
Has Abstractpub_date
1975-02-01 00:00:00pages
125-141issue
2eissn
0362-2525issn
1097-4687journal_volume
145pub_type
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