. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. • ^ /^L -•» -•* \. Figure 5. Morphological development of control and transplanted stage E1-E2 (2-4 cell stages) embryos at °C. A control embryo developed from the 4-cell stage to hatching in 13 days. Similarly, a transplanted embryo developed from the 2-cell stage to hatching at the same rate. The transplanted embryo was isolated from the same C'j'j mass as the control embryo. The transplanted embryos lagged behind the control embryo by 1 cleavage division at Day 0 because of the isolation and the l-h incubation in sal
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. • ^ /^L -•» -•* \. Figure 5. Morphological development of control and transplanted stage E1-E2 (2-4 cell stages) embryos at °C. A control embryo developed from the 4-cell stage to hatching in 13 days. Similarly, a transplanted embryo developed from the 2-cell stage to hatching at the same rate. The transplanted embryo was isolated from the same C'j'j mass as the control embryo. The transplanted embryos lagged behind the control embryo by 1 cleavage division at Day 0 because of the isolation and the l-h incubation in saline prior to transplantation. The host embryo (arrows) in the transplantation group was killed by heat shock (45 °C, 25 min) prior to transplantation. Scale bar: 300 /.mi. growth and survival, but failed to promote normal develop- ment over the long term. That embryos at early stages (pre-shell stages) fail to develop normally under various ex ovo conditions suggests that some key growth-promoting factors or certain environ- mental conditions are missing in ex ovo culture. It has been reported in several species that encapsulated embryos can- not develop normally if they are removed from the egg capsules at early stages of development (Morrill. 1982: Pechenik et al., 1984: Stockmann-Bosbach and Althoff. 1989: Meshcheryakov, 1990). This is probably because the environment in the capsttlar matrix is extremely complex and can hardly be mimicked in vitro. The situation is further complicated by the substantial variation in the composition of CF among species (Morrill et 1964; Morrill, 1982; Heras et 1998). Even less is known about the physical properties of the CF and the membranes surrounding it, such as viscosity, electrical charge, pressure, osmolarity, and pH (Beadle, 1969; Taylor. 1973; Morrill, 1982). For instance, this study indicates that Helisonui embryos naturally de- velop in a slightly acidic environment. Furthermore, acidic pH promoted growth and dev
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
