Development of the oocyte and its accessory cells of the polychaete, Diopatra cuprea (Bosc)

Abstract

The oocyte-nurse cell complex of the polychaetous annelid, Diqpatra cuprea, has been explored by various methods of light microscopy and by the technique of electron microscopy. Early in its development the complex appears as a string of cells floating within the coelomic cavity. As this string of cells develops, the volume of one cell (approximately the middle one) increases greatly; while that of the remaining cells, referred to as nurse cells, increase slightly. Due to this differential growth, the two opposing strands of nurse cells are displaced to one side of the oocyte.Nurse cells are joined to one another by cytoplasmic bridges. Cytoplasmic bridges also exist between the strands of nurse cells and the oocyte. The presence of numerous ribosomes within the bridges between the oocyte and nurse cells encourages us to suggest that this organelle may be transferred to the oocyte via this route. The transported ribosomes may be used by the maturing oocyte, or they may be stored by the egg to be utilized during embryogenesis. Moreover, we believe that the nurse cells are not involved in the production of the protein-carbohydrate yolk bodies for we think that these are elaborated by the endoplasmic reticulum in collaboration with certain Golgi complexes of the oocyte.

Ultrastructural study of oogenesis in <em>Marphysa sanguinea</em> (Annelida: Polychaeta: Eunicida) from the Lagoon of Tunis

“…The density of the microvillar tips in the mature oocyte of M. sanguinea (55-62 microvillar tips/µm) is comparable to that described for the spionid Marenzellaria viridis (50-60 microvillar tips/µm, Bochert 1996). The high density of microvilli tips increases the available surface area of the oocyte, as described for the nereid Platynereis dumerilii where microvilli form about 14.6% of the whole egg membrane surface (Kluge et al 1995) and for the onuphid Diopatra cuprea (Anderson and Huebner, 1968). This feature may facilitate the uptake of low molecular weight precursors through the oolema (see Huebner and Enderson 1976).…”

“…In M. sanguinea, the external membrane of the nuclear envelope of previtellogenic oocyte II forms blebs. The same process has been reported in another species of Eunicida Diopatra cuprea (Anderson and Huebner 1968). In his description of the mechanism of synthesis of yolk in crustacean oocytes Kessel (1968) emphasized the part played by the external membrane of the nuclear envelope in the process of the formation of new vesicular cisternae of the ER needed for yolk synthesis.…”

“…The same type of eggs was observed in many other species of polychaetes such as Diopatra cuprea (Anderson and Huebner 1968), Platynereis dumerilii (Dorresteijn 1990) and Nereis virens (Dondua et al 1997). It can be hypothesized that the differential distribution of cytoplasmic components leads to qualitative differences in blastomere cytoplasm.…”

Formation of germ-line cysts with a central cytoplasmic core is accompanied by specific orientation of mitotic spindles and partitioning of existing intercellular bridges

“…Linear chains of cystocytes have been found in some polychateous annelids (e.g. in Diopatra cuprea; Anderson and Huebner 1968) and in some crustaceans (Criel 1989;Kubrakiewicz et al 1991) and endopterygote hexapods (for a review, see Biliński 1994).…”

hu-li tai shao, a gene required for ring canal formation during Drosophila oogenesis, encodes a homolog of adducin.

“…Bridges that are morphologically similar to Drosophila ring canals interconnect the oocyte and its accessory cells, or groups of oocytes, in diverse invertebrate and vertebrate organisms (Franchi and Mandl 1962;Weakley 1967;Anderson and Huebner 1968;Dyer et al 1968;Zamboni and Gondos 1968), including humans (Gondos 1987). Spermatocytes and spermatids in many species also contain cytoplasmic bridges (Burgos and Fawcett 1955;Fawcett et al 1959;Hoage and Kessel 1968;Kalt 1973;Russel et al 1987).…”