Published online by Cambridge University Press: 27 March 2009
1. Five pairs of Suffolk twin lambs were used and one of each pair was injected twice daily with 2 mg. of a growth hormone preparation for 2 weeks.
2. Treatment was begun when they were between 3 and 4 weeks old, the total number of follicles in the Suffolk not being complete until 6 weeks old. Skin samples were taken at the beginning and end of the experiment.
3. It was found that in 0·25 sq. cm. of skin the total number of primary follicles was reduced from the beginning to end of the experiment in both control and treated groups, probably because of the expansion of skin area during that time. While the total number of secondary, ‘news’ and ‘plug’ follicles was also reduced in the control group, they were increased in the treated group.
4. Since the secondary to primary follicle ratio was 5·3:1 for the treated group as compared with 4·5:1 for the controls it is concluded that growth hormone increases the number of secondary follicles which develop during the early weeks of postnatal life.