Kaye, H.R. (1991). Sexual reproduction in four Caribbean commercial sponges. II. Oogenesis and transfer of bacterial symbionts. Invertebrate Reproduction and Development. 19 (1): 13-24.
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Kaye, H.R.
1991
Sexual reproduction in four Caribbean commercial sponges. II. Oogenesis and transfer of bacterial symbionts
Oogenesis in four commercial Caribbean sponge species, Hippospongia lachne, Spongia
barbara, S. cheiris and S. graminea, was studied using light and transmission electron
microscopy. Eggs and embryos develop asynchronously in localized endosomal nurseries
of these viviparous and gonochoristic species. Statistical analyses of specific morphological
characteristics of reproductive elements have unequivocally identified four specific stages
in the process of oogenesis. Oogonia undergo mitotic division to produce primary oocytes.
Meiotic division occurs producing secondary oocytes which are fertilized before zygotes
undergo major growth by phagocytosis and the transfer of nutrients through cytoplasmic
bridges. During cleavage of the zygote, umbilici form between embryos and nurse cell
layers and these function in the transfer of symbiotic bacteria and other mesohyl
substances from the maternal parent to the embryo. These symbionts were observed
dispersed between blastomeres of all young and maturing embryos and between internal
cells of cytodifferentiated parenchymella larvae. Extracellular transfer of symbiotic bacteria
from maternal tissues to developing embryos has not been reported in any other
viviparous invertebrate.