Perturbation of wool fibre cell differentiation by a mixture of bromodeoxyuridine and fluorodeoxyuridine

Abstract

As part of investigations into the pattern of cell division and differentiation in the wool follicle bulb, the thymidine analogue 5-bromo-2'-deoxyuridine was used to label cells in S phase. A mixture of 5-bromo-2deoxyuridine and 5-fluoro-2'-deoxyuridine was injected into sheep held at a constant plane of nutrition. fibre length growth rates were measured by injecting the animals with either 35S-labelled methionine or cysteine, followed by autoradiography of individual fibres. Fibres from 5-bromo-2'-deoxyuridine/5-fluoro-2'-deoxyuridine treated animals exhibited both abnormal cuticle scale patterns and disorganized ortho- and paracortex as determined by staining with methylene blue. Orthocortex differentiation in wool follicle bulb keratogenous zones was visualized using a monoclonal antibody specific for orthocortical cells (HiT 96). We determined that the normal pattern of orthocortical cell differentiation was reversibly inhibited by 5-bromo-2'-deoxyuridine/5-fluoro-2'-deoxyuridine treatment. Fibre length growth rate was reversibly decreased very slightly as a result of 5-bromo-2'-deoxyuridine/5-fluoro- 2'-deoxyuridine administration. We conclude that 5-bromo-2'-deoxyuridine/5-fluoro-2'-deoxyuridine can grossly perturb aspects of wool follicle bulb cell differentiation without profoundly affecting fibre length growth rate. Although 5-bromo-2'-deoxyuridine/5-fluoro-2~-deoxyuridine labelling is an inexpensive, nonradioactive method of visualizing S phase nuclei, the possibility of artefacts resulting from such treatment should be borne in mind.