The origin and translocation of primordial germ cells (PGCs) in goldfish Carassius auratus were studied, using both histological observations during embryonic development and by following the effects of partial elimination and duplication of blastoderm on the numbers of PGCs at the mid-blastu la stage.Goldfish PGCs are distinguished from somatic cells by their large size, distinct outline and large nucleus, because they are morphologically identical with those of the other fish species . They were locat ed in the gonadal anlage at ten days post-fertilization, and were traced back to 30-hour post-fertiliza tion (hpf) embryos with seven to nine somites. They were distributed widely in an embryo at 30 hpf, ex cept for brain, spinal cord, notochord and the enveloping layer. The numbers of PGCs did not increase from 30 hours to ten days post-fertilization. When the lower part of the blastoderm was eliminated at the mid-blastula stage, the number of PGCs decreased at the gonadal anlage. But, elimination of the up per part at same stage did not effect the number of PGCs. Moreover, the number of PGCs increased in the duplicated embryos, in which a normal blastoderm was transplanted onto a host embryo from which the upper part of the blastoderm had been removed. These results suggest that the PGCs-bear ing-cells could be predetermined by cytoplasmic factor and were already distributed in the lower part of blastoderm at the mid-blastula stage, and that they can not regenerate after that.

Germ-line chimerism was successfully induced by blastoderm transplantation from donor triploid crucian carp, which reproduces gynogenetically, to recipient diploid goldfish, which reproduces bisexually. Lower part of donor blastoderm including primordial germ cells (PGCs) was sandwiched between recipient blastoderm at the mid- to late-blastula stage. When donor grafts were prepared from intact embryos or ventralized ones by removing vegetal yolk hemisphere at the 1- to 2-cell stage, malformations including double axes were observed in the resultant chimeras transplanted with grafts from intact embryos at the hatching stage, while a few malformations in those from ventralized embryos. PGCs originated from donor grafts were observed around the gonadal anlage at 10 days post-fertilization in chimeras. When ploidy of erythrocytes and epidermal cells in chimeric fish was examined by flow-cytometry, no triploid cells were detected at 1- and 5-year-old chimeras. Three-year-old chimeric fish (n = 5) laid eggs originated from the donor together with those from the recipient. The frequency of eggs from the donor crucian carp blastoderm varied from 3.1 to 89.3% between chimeras.

Eight species of Pectinariidae de Quatrefages, 1866 were recorded from Japan and adjacent waters. We studied four species of the family and redescribe the poorly known species from the Seto Inland Sea and Ariake Sound, Kyushu based on recently collected material. The species covered in this study are Amphictene japonica (Nilsson, 1928), Lagis bocki (Hessle, 1917), Pectinaria okudai (Imajima & Hartman, 1964) and Pectinaria hiuchiensis Kitamori, 1965.