Riviere H L, Gentz E J, Timm K I
School of Dentistry, Department of Biological Structure and Function, Oregon Health Science University, Portland 97201-3097, USA.
Anat Rec. 1997 Dec;249(4):441-8. doi: 10.1002/(SICI)1097-0185(199712)249:4<441::AID-AR3>3.0.CO;2-U.
Attempts have been made to define the relationships among the South American camelids, the guanaco, llama, alpaca, and vicuna, by comparing the morphology of their incisors. The alpaca has been reported to have an incisor morphology similar to the vicuna, lacking enamel on the lingual surface. The llama and guanaco are said to have enamel on both the labial and lingual surface of their incisor teeth. These comparisons have been based on gross morphological observations and not on histologic analysis. This study was undertaken to determine whether or not alpaca teeth have enamel on the lingual surface. The cross-sectional histologic anatomy of the incisor teeth was compared in two closely related South American camelid species, the llama (Lama glama), and the alpaca (Lama pacos). Thick sections (300 microm) and scanning electron microscopy were the techniques utilized. The mandibular first, second, and third incisors were examined in four llamas and five alpacas. A substantial layer of enamel was present on all surfaces of all llama incisors. The enamel layer on the labial surface of the alpaca incisors closely resembled that found in the llama. The enamel layer on the lingual surface of the alpaca incisors, although greatly reduced, was distinctly present. Alpacas may be more closely related to guanacos and llamas than to vicunas. A histologic study of vicuna incisors would help to better define the relationships of the four camelids.
人们试图通过比较南美骆驼科动物原驼、美洲驼、羊驼和小羊驼的门齿形态来确定它们之间的关系。据报道，羊驼的门齿形态与小羊驼相似，舌面无釉质。据说美洲驼和原驼的门齿唇面和舌面都有釉质。这些比较是基于大体形态学观察，而非组织学分析。本研究旨在确定羊驼牙齿的舌面是否有釉质。对两种亲缘关系密切的南美骆驼科动物——美洲驼（小羊驼）和羊驼（无峰驼）的门齿进行了横断面组织解剖学比较。采用厚切片（300微米）和扫描电子显微镜技术。检查了4只美洲驼和5只羊驼的下颌第一、第二和第三门齿。所有美洲驼门齿的所有表面都有一层厚厚的釉质。羊驼门齿唇面的釉质层与美洲驼的非常相似。羊驼门齿舌面的釉质层虽然大大减少，但明显存在。羊驼与原驼和美洲驼的关系可能比与小羊驼的关系更密切。对小羊驼门齿进行组织学研究将有助于更好地确定这四种骆驼科动物之间的关系。
