THE EFFECTS OF EXOGENEOUS MELATONIN AND PROLACTIN ON WOOL FOLLICLE DEVELOPMENT IN OVINE FETAL SKIN-GRAFTS

The fleece of the Merino sheep is composed predominantly of wool fibre s grown froin secondary wool follicles. This study investigates the ef fects of melatonin and prolactin on the development of secondary folli cles in grafted ovine foetal skin. Skin from day 85 ovine foetuses was grafted onto nude mice, developed for 40 days and then excised. Mice received either 30 mug prolactin ip mouse-1 day-1 (P), one melatonin i mplant (Regulin(R)) sc mouse-1 (M), commencing at grafting or no furth er treatment (C). Wool follicle density and development, were assessed in grafted skin and compared with day 125 control foetal skin. Cuticl e structure of graft fibres was also examined and compared with those of day 125 foetuses. Total follicle density and the rate of follicle i nitiation were reduced in the grafts compared with control foetal skin . Total follicle density did not vary significantly between treatments , but the number of derived secondary follicles was greater in grafts from mice receiving prolactin (group P). Follicles in grafted skin wer e larger, produced medullated fibres. and were not grouped, in compari son with follicles in the, control foetal skin. Epidermal thickness wa s greater in grafts than in control foetal skin. The cuticle structure of graft fibres from all groups was similar to the control wool fibre s. These findings indicate that prolactin, but not, melatonin, may be involved in the regulation of derived secondary follicle development.