. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 174 R. P. ELINSON ET AL imental purposes, embryos can he cultured in water (Lynn and Peadon. 1955) or in 20% Steinberg's solution (Elinson. 1987b). Jellied embryos are submerged in 20% Steinberg's, and the outer and middle jelly layers are removed with watchmaker's forceps. Embryos with intact jelly show re- tarded development, possibly because of reduced gas ex- change. It is initially difficult to remove the fertilization envelope and inner jelly layer, but it becomes easy to do so by Townsend/Stewart stage 7. The embryos
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 174 R. P. ELINSON ET AL imental purposes, embryos can he cultured in water (Lynn and Peadon. 1955) or in 20% Steinberg's solution (Elinson. 1987b). Jellied embryos are submerged in 20% Steinberg's, and the outer and middle jelly layers are removed with watchmaker's forceps. Embryos with intact jelly show re- tarded development, possibly because of reduced gas ex- change. It is initially difficult to remove the fertilization envelope and inner jelly layer, but it becomes easy to do so by Townsend/Stewart stage 7. The embryos continue to develop in 20% Steinberg's until Townsend/Stewart stages 14-15 when they are allowed to crawl onto land. Development of embryos from most clutches occurs normally in 20% Steinberg's, although embryos in some clutches develop edema around Townsend/Stewart stage 7. Normal development Eleutherodactylus coqui lends itself to the study of de- velopment because of several features. Eggs are large, av- eraging 4 mm, and are virtually unpigmented for the first two-thirds of development. Many internal features, in- cluding the cardiovascular system, nervous system, the development of eyes and ears, and the formation of en- dolymphatic calcium deposits, are clearly visible in the rather translucent embryo (Townsend and Stewart, 1985). Developmental studies have been conducted on several Eleutherodactylus species, including studies by Sampson (1904), Lynn (1942), Gitlin (1944), Lynn and Lutz (1946, 1947), Coin (1947). Jameson (1950), Hughes (1959, 1962), Adamson el al. (1960). Chibon (1960), Valett and Jameson (1961), Wake (1978), and Townsend and Stewart (1985). Detailed histological descriptions of organ for- mation are provided by Lynn (1942), Adamson et al. (1960). and Chibon (1962). Unlike the many normal tables available for Rana spe- cies, A". Uievis, and other species with typical embryonic development followed by a free-living larval stage, there are few detailed
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
