Wool follicles initiate, develop and produce fibres in ovine foetal skin grafts.

Abstract

Proc. Aust. Soc, Anim. Prod. Vol. 18 WOOL FOLLICLES INITIATE, DEVELOP AND PRODUCE IN OVINE FOETAL SKIN GRAFTS FIBRES C.E. McCLOGHRY*, D.E. HOLLIS*, K.A. RAPHAEL*, R.C. MARSHALL**, J.P. KENNEDY*** and P.C. WYNN* Research into the mechanisms controlling wool follicle initiation and development has been severely hampered by the inaccessibility of the foetal sheep skin within the uterus. It was our aim to develop a method whereby skin from the foetus could be maintained outside the uterine environment and still retain its ability to initiate follicles that would develop and produce wool fibres. The nude mouse (nu/nu) is athymic. The thymus governs the mechanisms for the rejection of foreign substances and the level of antibody production within the The absence of a thymus in the nude mouse causes it to be immunoMYdeficient, enabling foreign tissue to be grafted onto the mouse without being rejected. Using the adult nude mouse as a recipient, skin samples were removed from the mid-side region of ovine foetuses ranging from day 45 to day 105 of gestation, and transferred to graft beds prepared on the mice. The grafts were allowed to develop for 20 days on the hosts, at which time the mice were terminated and grafts removed and processed for histological examination. Graft success rate varied from 67-100%. Successful grafts were elevated and well defined whereas the graft beds in which transplanted tissue failed to Follicle initiation was observed in grow, constricted to form small scars. grafts obtained from day 45 foetal skin (grafted prior to the commencement of follicle initiation), and also in grafts prepared from skin containing developing follicles (day 65-105). This event, the first stage of follicle development, was characterized by the aggregation of dermal, and overlying epidermal cells at regular intervals in the skin. In days 65-105 grafts, in which follicles were already present, the newly initiated follicles developed simultaneously along with those already present according to the normal sequence of events observed in foetal skin (Hardy and Lyne 1956). However, in many cases this pattern of developmental events appeared to occur more quickly in the grafted tissue than on the normal foetus in utero. Grafts from day 85, 95 and 105 skin produced a profuse eruption of fibres. Electrophoretic analysis of these fibres (Marshall and Gillespie 1982) showed that the pattern of proteins resembled the characteristic high and low sulphur and high tyrosine proteins which form the microfibrils and matrix of wool fibres. Graft life was indefinite, limited only by the longevity of the host, which is particularly susceptible to generalized infection. A constant feature of all grafts was the initial loss of the periderm (surface layer of cells) and the cornification of the epidermis. This is in marked contrast to normal epidennal development, where the periderm is shed at a much later stage. We believe this unique model shows great promise as a system for investigating the factors controlling follice initiation and development in sheep. BARDY, M-H, and LYNE, A.G. (1956), Aust. J. Biol, Sci. 9: 423. MARSHALL, RX. and GILLESPIE, J.M, (1982). J, Forensic Sci. Soc. 22: 377. * +** CSIRO, Division of Animal Production, PO Box 239, Blacktom, N.S.W. 2148. CSIRO, Division of Wool Technology, 343 Royal Parade, Parkville, Vic. 3052. Dept Wool and Animal Science, University of New South Wales Kensington, N.S.W. 2033. 518