GROWTH-FACTOR EXPRESSION IN SKIN DURING WOOL FOLLICLE DEVELOPMENT

A variety of growth factors are likely to be involved in initiation an d morphogenesis of wool follicles, To enable direct comparisons of the expression of different growth factors, reverse transcriptase-polymer ase chain reactions (RT-PCR) were developed for ovine and murine TGF a lpha, TGF beta 1, TGF beta 2, TGF beta 3, IGF1, IGF2, and FGF-2, which could all be carried out on a single cDNA sample, These RT-PCR were u sed with 16 sheep RNA samples from different foetal stages, neonatal s heep and mouse skin, The mRNAs for these growth factors were detected throughout gestation in sheep skin, except for TGF beta 1 mRNA which w as not expressed in 51-day-old skin, but was expressed in 54-day and o lder samples, Since the first microscopically visible changes of folli cle initiation occur around 62 days gestation, these results suggest t hat TGF beta 1 expression may be a signal for follicle initiation.