. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SHELL DEPOSITION IN AN ACOEL 57 Type A 16 5 6 7 8 9 1C 11 Feret Diameter (x 100 nm) 13 H 15 TypeB find _n 567 8 9 1C 11 Feret Diameter (x 100 nm) 12 13 14 15 Figure 2. Feret diameter distribution of granule Types A and B. Each number on the abscissa represents the stated value ±; n = 200. loses some of its volume, shrinking away from the shell. Since the two possibilities affect the interpretation of the changes in volume densities of the granules, the absolute volumes of eggs prior to egg-laying and of embryos after egg-
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. SHELL DEPOSITION IN AN ACOEL 57 Type A 16 5 6 7 8 9 1C 11 Feret Diameter (x 100 nm) 13 H 15 TypeB find _n 567 8 9 1C 11 Feret Diameter (x 100 nm) 12 13 14 15 Figure 2. Feret diameter distribution of granule Types A and B. Each number on the abscissa represents the stated value ±; n = 200. loses some of its volume, shrinking away from the shell. Since the two possibilities affect the interpretation of the changes in volume densities of the granules, the absolute volumes of eggs prior to egg-laying and of embryos after egg-laying were determined. Serial 2 ^in-thick sections were viewed with a Zeiss Axioskop light microscope equipped with a Sony DXC-3000A color video camera and a Sony PVM-1343MD Trinitron color monitor. Each section of egg or embryo was traced from the monitor screen onto transparent plastic. The ZIDAS was used to calculate the area of each drawn section; the area, in turn, was multiplied by the thickness of the sections and these numbers summed for all sections to determine the volume of each egg or embryo. Four eggs with mature shells and four laid eggs were analyzed. ANOVA was used to com- pare the mean volume of eggs with mature shells to that of embryos within the laid eggs. Results Stages of shell formation Based on the ultrastructural features described in detail below, development of the eggshell in Convoluta pulchra -. 14 - 10 - Ol D m 6 3 I • Type A E3 TypeB D Lipid. JL PS M Stage of Shell Synthesis Figure 3. Volume densities of granular inclusions. PS = stage of Primary Shell synthesis; MS = stage of Mature Shell synthesis; M = stage of Mature Shell; L = stage of Laid Shell. was divided into four sequential stages: Primary Shell Synthesis, Mature Shell Synthesis, Mature Shell, and Laid Shell. The germinal vesicle persists into the Mature Shell stage, during which it breaks down. Because the time of fertilization is not known for the species, the Mature Shell stage ma
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
