Tateki Chikamune

Germ line chimera produced by transfer of cultured chick primordial germ cells.

Intrinsic primordial germ cells (PGCs) from stage 27 (5‐day‐old) chick embryonic germinal ridges were cultured in vitro for a further 5 days, and shown to proliferate on stroma cells derived from the germinal ridge. To determine whether these cultured PGCs could colonize and contribute to the germ‐line, PGCs were isolated by gentle pipetting, labeled with PKH26 fluorescent dye and injected into the blood stream of stage 17 (2.5‐day‐old) chick embryos. The recipient embryos were incubated until they reached stage 28. Thin sections of these embryos were analysed by fluorescent confocal laser microscopy. These analyses showed that the labeled donor PGCs had migrated into the germinal ridges of the recipient embryos, and transplanted PGCs had undergone at least 3‐7 divisions. These results suggest that PGCs that had passed far beyond the migration stage in vivo were still able to migrate, colonize and proliferate in recipient chick embryonic gonads.

Proliferation of chick primordial germ cells cultured on stroma cells from the germinal ridge.

Fluorescent reagent‐labelled PGCs isolated from the blood of 2‐day‐old chick embryos were cultured on stroma cells derived from 5‐day‐old germinal ridge in Medium 199 supplemented with 10% FBS, human IGF‐1, bovine FGF‐b, and murine LIF. In 7 experiments, the number of MCs increased by an average of 4.8 fold in 4 days. Intrinsic PGCs in the 5‐day embryonic germinal ridge were observed loosely attached to the stroma cells, and they also increased 3.8 fold during culture for 4 days. These results indicate the possibility of applying this culture method to the production of transgenic chickens.

Study on the concentration of circulating primordial germ cells (cPGCs) in early chick embryos.

Experiments were conducted to elucidate the factor that influences the concentration of circulating primordial germ cells (cPGCs) in two-day old chick embryos. The concentration of cPGCs was observed to be highest at stage 14 (66.9 +/- 23.2 microliters) and decreased thereafter. However, considerable egg to egg variations in cPGC concentration, especially at stages 13, 14, 15, and 16 were observed. After conducting experiments to elucidate the source of egg to egg variation in cPGC concentration among embryos, it was revealed that there are hens that lay eggs which contain either constantly high (more than 80 PGCs/microliter) or constantly low (less than 30 PGCs/microliter) concentration of cPGCs. The results obtained from the present experiments showed that one of the major source of egg to egg variation in the concentration of cPGCs was due to the individual differences among females that produced the eggs.

Simple method for isolation of primordial germ cells from chick embryos.

A simple one step centrifugation method was developed for purification of primordial germ cells (PGCs) of chick embryos. PGCs, constituting less than 0.1% of the total blood cells of stage 13-14 embryos that contained a microliter amount of blood, were concentrated at the interface of a 6.3% (w/v) and 14.4% (w/v) Ficoll bilayer by centrifugation at 800 x g for 30 min. the purity of these PGCs was 86%, which was 22 times that obtained previously.

The Effects of Nursing Environmental Conditions on aliability in Inbred, Random Bred and F1 Hybrid of Young Mice

近交系,近交系間F1および無作為交配マゥスを用いて,母の哺育能力が子群の15日令体重および開眼時期の変異に及ぼす影響に関して調査した。得られた結果は次の如くである.1) 分散分析の結果,15日令体重および開眼時期のいずれにおいても,哺育母の哺育能力が大きな影響を及ぼし,子の遺伝性の違いにもとつく部分も有意であつた.他方性による相違およびこれらの間の相互作用は有意でなかつた.2) 15日令体重の変異は,いずれの群においても哺育環境が劣つた条件下において増加したが,とりわけ近交系群の変異の増加が著しかつた。3) 無作為交配群および近交系間F1群の開眼時期の変異は,劣つた哺育環境下において増加する傾向がみられた.他方近交系群の開眼時期の変異は,哺育環境の優劣に関係なく常に大きな価を示した.4) 近交系間F1および無作為交配群の15日令体重の変異は,哺育環境の変異が増加するにしたがつて増加した.これは,ヘテロ性の高い個体が,自己がおかれた部分的状態に対して適応力が高く,よりflexibleに発育する能力を有するためと推論された.