甲状腺剤が緬羊の毛胞群に及ぼす影響

This work was undertaken to investigate the effect of thyroid preparation on the number of wool follicles, especially of secondary follicles and the value of the secondary to primary follicle ratio (S/P ratio) of skin samples of sheep. The animals used were four pairs of twins of Corriedale lambs and those were classified into two groups, each one of two groups being consisted of two pairs and one of each pair of one group was subcutaneously injected daily for 15 weeks with 4 mg of thyroid from two weeks after birth and one of each pair of the other group from four weeks after birth. Small skin samples were removed from left and right mid-side of each lamb at the beginning and end of the experiment and the histological preparations of skin samples were made and the number of primary follicles, secondary follicles, total follicles and the value of S/P ratio were counted and their changes during the period of experiment in control and treated groups were compared. The results obtained were as follows; 1) It was found that the number of primary follicles in both control and treated groups was reduced from the beginning to the end of the experiment, probably because of the expansion of skin area during the period of experiment. 2) The number of secondary follicles in the group in which treatment was begun when lambs were two weeks old, was reduced in control group and increased in treated group at the end of the experiment. The number of secondary follicles in the group in which treatment was begun when lambs were 4 weeks old, was reduced in both control and treated groups. 3) The ratio of secondary to primary follicle (S/P ratio) showed a greater value at the end of the experiment than at the beginning in both control and treated groups. In both two groups in which treatment was begun when lambs were two weeks and four weeks old, mean values of S/P ratio for the treated group were 9.65, 8.76, as compared with 8.92, 8.33 for the control group at the end of the experiment. 4) It seems that by injection of thyroid preparation during the early weeks of postnatal life it may be possible to increase the number of secondary follicles and the value of S/P ratio of sheep skin.