Takayoshi Ino

Mitotic Activity in the Inbred and Hybrid Quail Embryos

In the previous papers5), marked retardation in embryonic development and decrease in embryonic weight were found in the inbred lines, while restoration of embryonic development and embryonic weight was observed in crosses between inbred lines of Japanese quail. It is well known 2-4,10) that cell number increases during morphogenesis of the early chick embryos and that a highly positive correlation is found between the early embryonic development and cell number. Furthermore, mitotic activity such as the number of mitotic cells and mitotic index 4,8,11) is used as an indication of cell increase in relation to the rate of embryonic development. However, there is very little published information on the relationship between embryonic development and mitotic activity of quail embryos. This study was undertaken to investigate the mitotic activity in the inbred and hybrid quail embryos. Materials and Methods The Japanese quail used in this study consisted of inbred lines (F=59.4%), crossbreds obtained by crossing between inbred lines (F= 50.0%) and a randombred population as described in our previous report5). The number of pair-matings used in the inbred lines, crossbreds and in randombred population were 38, 34 and 40, respectively. The quail were kept under 14 hours light per day and fed freely with a diet containing 24% protein. The eggs for this study were collected and incubated for 48 hours at 38.2°C. At the

Relationship between Egg Fertility and Testes Weight and Semen Characteristics in Japanese Quail Bred by Full-Sib Mating

本研究は,近交による日本ウズラの受精率低下の原因を明らかにするために,近交によっておこる受精率の低下と雄の性機能との関係について検討した.実験に使用した日本ウズラは,近交群と無作為交配群の1,2世代である.1. 近交群の受精率は2世代目で急激な低下がみられ,無作為交配群との間に有意差が認められた.2. 近交群では無作為交配群に比較して,精巣重量,精液量,精子濃度,精子の運動性はすべて減少し,これに対して奇形精子の出現頻度は増加した.しかしながら,精液pHには両群間で差異が認められなかった.3. 受精率の高い群では受精率の低い群に比べて,精巣重量,精液量,精子濃度,精子の運動性,奇形精子の出現頻度はいずれもすぐれた値を示した.4. 相関係数は,受精率と精巣重量の間では+0.535,受精率と精液量の間では+0.547,受精率と精子濃度の間では+0.824,受精率と精子の運動性の間では+0.875,受精率と奇形精子の出現頻度の間では-0.862となり,いずれも有意な値が認められた.5. 以上の結果から,近交による受精率の低下は雄での造精機能全体の低下,障害に起因するものと考えられる.