Lavker R M, Sun T T
J Invest Dermatol. 1983 Jul;81(1 Suppl):121s-7s. doi: 10.1111/1523-1747.ep12540880.
Stem cells are by definition present in all self-renewing tissues and are believed to play a central role in cell growth and differentiation. Existing evidence suggests that a subpopulation of epidermal basal keratinocytes represents stem cells; however, these cells have never been positively identified. In this paper we review evidence that in monkey palm epidermis there exist two morphologically distinct subpopulations of basal keratinocytes that are spatially segregated. One population, located in the shallow rete ridges, is characterized by a cytoplasm filled with tonofilaments and a highly convoluted ("serrated") dermal-epidermal junction; these cells may play a role in anchoring the epidermis to the dermis. In contrast, the other population, located at the tips of deep rete ridges, is characterized by a "primitive" cytoplasm containing abundant melanosomes and a relatively flattened ("nonserrated") dermal-epidermal junction. Tritiated thymidine labeling experiments suggest that the nonserrated basal keratinocytes are slow-cycling; however, a highly proliferative population of keratinocytes can be identified immediately above these basal cells. These findings are consistent with the concept that the nonserrated basal keratinocytes may represent stem cells that give rise to suprabasally located, transient amplifying cells before undergoing terminal differentiation. Monkey palm epidermis provides a model system for further studies of primate epidermal stem cells.
根据定义，干细胞存在于所有自我更新的组织中，并被认为在细胞生长和分化中起核心作用。现有证据表明，表皮基底角质形成细胞的一个亚群代表干细胞；然而，这些细胞从未被明确鉴定出来。在本文中，我们回顾了相关证据，即在猴掌表皮中存在两种形态上不同的基底角质形成细胞亚群，它们在空间上是分隔的。其中一群位于浅的 rete 嵴中，其特征是细胞质充满张力丝，真皮 - 表皮连接处高度卷曲（“锯齿状”）；这些细胞可能在将表皮锚定到真皮中起作用。相比之下，另一群位于深 rete 嵴的尖端，其特征是“原始”细胞质含有丰富的黑素体，真皮 - 表皮连接处相对扁平（“非锯齿状”）。氚标记胸腺嘧啶核苷标记实验表明，非锯齿状基底角质形成细胞的细胞周期较慢；然而，在这些基底细胞上方紧邻处可鉴定出一群高度增殖的角质形成细胞。这些发现与以下概念一致，即非锯齿状基底角质形成细胞可能代表干细胞，在经历终末分化之前产生位于基底上方的短暂扩增细胞。猴掌表皮为进一步研究灵长类表皮干细胞提供了一个模型系统。
