. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PREMETAMORPHIC SHELL MINERALIZATION 219. Sh 8 £&•' ' 7 ,fr-i" !.• ;... ' -.; ;, -;.., iv-a-rfJyW • '• - Nu ^ ".. 7' "-•'. -;*^*" • ' . 2 um FIGURES 7 and 8. Sections through trochophores (33-h-old) of the bivalve Spisula solidissima at onset of shell mineralization. Both figures are in the same orientation. The SFI lumen (arrowheads) was still present. FIGURE 7. Schematic diagram of section through ciliated (C) trochophore showing two invaginations, the archenteron (A) and the dorsal shell field in
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PREMETAMORPHIC SHELL MINERALIZATION 219. Sh 8 £&•' ' 7 ,fr-i" !.• ;... ' -.; ;, -;.., iv-a-rfJyW • '• - Nu ^ ".. 7' "-•'. -;*^*" • ' . 2 um FIGURES 7 and 8. Sections through trochophores (33-h-old) of the bivalve Spisula solidissima at onset of shell mineralization. Both figures are in the same orientation. The SFI lumen (arrowheads) was still present. FIGURE 7. Schematic diagram of section through ciliated (C) trochophore showing two invaginations, the archenteron (A) and the dorsal shell field invagination associated with formation of the early shell (Sh). The small amount of shell material present at this stage would lie at the tip of the pointer and is omitted for clarity. Not to scale. FIGURE 8. Unstained section through a trochophore fixed in potassium pyroantimonate—osmium tetroxide to localize calcium at onset of shell mineralization. Electron-dense reaction product (arrows) was observed within the shell field cells, extracellularly within the narrow SFI lumen (arrowheads), and clustered at the junction of the SFI pore and the extrapallial space beneath the shell (Sh). Nu = nucleus. A = artifact. transmission electron microprobe analysis, some calcium may be present in the lumen of the shell field invagination of Spisula solidissima during early shell formation. In one embryo of the gastropod Hermissenda crassicornis incubated in PPA, an elongated region consistent with the location and morphology of the SFI was located (Figs, 9, 10). Within this region were large clusters of electron-dense reaction product, in addition to moderately electron-dense material resembling the 'albumen' of the capsular fluid found elsewhere between the embryo and the capsule wall. Within the shell field cells the reaction product was much finer grained (not clumped) than that observed extracellularly. Electron microprobe analysis of reaction product in the lumen of the
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
