Johnsen D C, Karlsson U L
Anat Rec. 1977 Sep;189(1):29-43. doi: 10.1002/ar.1091890103.
Pulp development was studied with light and electron microscopy in apical portions of cat primary and permanent incisors at various stages of development in order to qualitatively assess hypothesized differences during maturation. Primary and permanent tooth pulps passed through similar stages up to when the primary teeth began to resorb. At that point permanent tooth pulps continued to develop in complexity relative to myelinated axons and developed thin epineurial sheaths. Although the stages were similar in several regards, the time needed by the permanent tooth pulps to reach each stage was considerably greater than for the primary tooth pulps. It is of interest that the young permanent teeth had only a small portion of their final complement of nerves in spite of their relatively complete development. Individual axons, especially myelinated axons, appeared more immature in younger primary and permanent teeth. This suggests a less mature sensory capability for erupting primary teeth as compared to fully developed primary teeth as well as for erupting and young permanent teeth compared to old permanent teeth.
为了定性评估发育成熟过程中假定的差异，利用光镜和电镜研究了处于不同发育阶段的猫乳切牙和恒切牙根尖部分的牙髓发育情况。乳牙和恒牙牙髓在乳牙开始吸收之前经历相似的阶段。此时，恒牙牙髓相对于有髓轴突在复杂性上继续发育，并形成薄的神经外膜鞘。尽管在几个方面阶段相似，但恒牙牙髓达到每个阶段所需的时间比乳牙牙髓长得多。有趣的是，尽管年轻恒牙发育相对完整，但其最终神经补充只有一小部分。在较年轻的乳牙和恒牙中，单个轴突，尤其是有髓轴突，看起来更不成熟。这表明，与完全发育的乳牙相比，正在萌出的乳牙感觉能力较不成熟，与老恒牙相比，正在萌出的恒牙和年轻恒牙感觉能力也较不成熟。
