. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 210 IIKKMFKT [•.. I' tubes by means of heavy dissecting needles. Opercular brood pouches containing embryos, at various stages of development, together with pouches from which larvae recently emerged, were removed at the base of the opercular crowrn with #5 watch- maker's forceps. The brood pouches were fixed in an ice-cooled mixture of one part 5% glutaraldehyde. one part 5% osmium tetroxide, and two parts of M phos- phate buffer at pM (Stanley, 1967). Numerous attempts to use glutaraldehyde, utilizing a num
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 210 IIKKMFKT [•.. I' tubes by means of heavy dissecting needles. Opercular brood pouches containing embryos, at various stages of development, together with pouches from which larvae recently emerged, were removed at the base of the opercular crowrn with #5 watch- maker's forceps. The brood pouches were fixed in an ice-cooled mixture of one part 5% glutaraldehyde. one part 5% osmium tetroxide, and two parts of M phos- phate buffer at pM (Stanley, 1967). Numerous attempts to use glutaraldehyde, utilizing a number of different buffers and made isotonic with sea water, as a primary fixative have not been successful with this material. Following fixation, the opercular brood pouches were dehydrated in a graded series of alcohols from 30% to absolute and then embedded in Epon 812 (Luft, 1961). Brood pouches were flat embedded, cut out of block, and oriented, in three planes, on chucks. Each specimen was pared down with a razor blade to just within the region of the pore. One micron thick sections were then cut with a Porter Blum MT-1, affixed to glass slides and stained with Richardson's stain (Richardson, Jarett, and Finke, 1960). Adjacent thin sections were cut with a diamond knife, picked up on 200 mesh grids, and stained in saturated 50/f. alcoholic uranyl acetate for 20 minutes followed by lead citrate reagent (Reynolds, 1963) for five minutes. The specimens were examined and photographed with an RCA EMU-3E electron microscope. RESULTS The operculum of Spirorbis uiocrchi contains a spacious cavity, the brood chamber, and is capped by a characteristically bilobed calcareous plate (Fig. 1). As observed from the side with a dissecting microscope, a thickening, indicating the site of the opercular pore, can be seen in the opercular epithelium. A section through a brood pouch containing embryos shows that the epithelium surrounding the opercular pore is simple columnar, the cells vary
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
