Parry A L, Nixon A J, Craven A J, Pearson A J
AgResearch, Flock House Agricultural Centre, Bulls, New Zealand.
Acta Anat (Basel). 1995;154(4):283-99. doi: 10.1159/000147780.
Exposure of New Zealand Wiltshire sheep to long days, following 24 weeks of short days, caused a synchronised out-of-season wool follicle growth cycle. Skin biopsies were collected at intervals between 3 and 30 days and follicles were examined by light microscopy in both transverse and longitudinal section to describe the regressive (catagen), resting (telogen) and regenerative (proanagen) stages of the induced growth cycle. Follicles were generally in the growing phase (anagen) during short day treatment but by day 20 after exposure to long day photoperiod. 16% of follicles were in late catagen. By day 52, all follicles were in various stages of catagen, telogen and proanagen. The progression through the cycle occurred more slowly, but was morphologically similar to follicle growth cycles reported in rodents and goats, induced by plucking or melatonin, respectively. Follicles in early catagen were rarely observed, possibly reflecting the brevity of this phase of the cycle. Late catagen follicles were distinguished by the presence of a brush end and an inner root sheath, the latter disappearing as follicles entered telogen. Immunocytochemistry of proliferating cell nuclear antigen provided evidence that mitotic activity in the follicle bulb ceased completely during the brief telogen phase. The simultaneous absence of type I intermediate filament keratin mRNA indicated that keratinocyte differentiation had also been interrupted. Cell proliferation was re-established in early proanagen prior to observable changes in the follicle microanatomy. The relatively synchronised follicle growth cycle induced by photoperiod manipulation represents a potentially useful model for the study of changes in follicle ultrastructure and the endocrine and biochemical regulation of seasonal hair growth patterns.
在经历24周短日照后，将新西兰威尔特郡绵羊暴露于长日照环境下，引发了同步的非季节性毛囊生长周期。在3至30天的间隔时间内采集皮肤活检样本，并通过光学显微镜对毛囊进行横切和纵切检查，以描述诱导生长周期中的退行期（退行期）、静止期（休止期）和再生期（前期生长期）。在短日照处理期间，毛囊通常处于生长期（生长期），但在暴露于长日照光周期后第20天，16%的毛囊处于晚期退行期。到第52天，所有毛囊都处于退行期、休止期和前期生长期的不同阶段。整个周期的进展较为缓慢，但在形态上与分别由拔毛或褪黑素诱导的啮齿动物和山羊的毛囊生长周期相似。很少观察到早期退行期的毛囊，这可能反映了该周期这一阶段的短暂性。晚期退行期毛囊的特征是存在刷状末端和内根鞘，随着毛囊进入休止期，内根鞘消失。增殖细胞核抗原的免疫细胞化学分析提供了证据，表明在短暂的休止期，毛囊球中的有丝分裂活动完全停止。I型中间丝角蛋白mRNA的同时缺失表明角质形成细胞的分化也被中断。在毛囊微解剖结构出现明显变化之前，早期前期生长期就重新建立了细胞增殖。光周期调控诱导的相对同步的毛囊生长周期，为研究毛囊超微结构变化以及季节性毛发生长模式的内分泌和生化调节提供了一个潜在有用的模型。
