study on the development, aging and the regulation factors of the maintenance of the masticatory organs

咀嚼器官的发育、衰老和维持涉及多种因素。在本研究中，我们调查的感觉输入的缺乏牙周膜中的感觉末梢，导致牙齿缺失，和性激素对三叉神经运动核（Mo 5）的影响。此外，我们还研究了咬肌和三叉神经运动神经元中雌激素和/或雄激素受体的生后出现情况，感觉末梢感觉输入的缺乏导致支配咬肌的Mo 5神经元数量减少。在发育中的小鼠咬肌中，我们观察到了出生后第5天的阳性免疫反应细胞核。免疫反应性无性别差异。在M05中，雌激素和雄激素受体的阳性免疫反应分别在出生后第5天和第20天检测到。给雌性小鼠注射5 α-二氢睾酮，M05中运动神经元的数量增加到阳性比例。相比之下，在用17β-雌激素处理的雄性小鼠中，运动神经元数量下降到更典型的雌性水平。醋酸环丙孕酮，雄激素拮抗剂，治疗显着减少未成熟雄性小鼠的Mo 5运动神经元的数量。Me 5中的感觉神经元不受任何处理的影响。因此，雄激素和雌激素参与出生后的变化，运动神经元数量的Mo 5，但不是在数量的Me 5。

The various factors are involved in the development, aging and maintaenance of the masticatory organs. In the present study, we investigated effects of the lack of the sensory input from the sensory endings in the periodontal ligament, resulted from tooth loss , and those of sex hormones on the trigeminal motor nucleus (Mo5) . Moreover, we studied the postnatal appearance of the oestrogen and/or androgen receptors in the masseter muscle and trigeminal motor nuerones.The lack of the sensory input from the sensory endings caused decrease in the number of Mo5 neurones that innervate the masseter muscle. In the masseter muscle of developing mice, we observed the positive immunoreactive nuclei by the 5th postnatal day in mice. No sex difference in the immunoreactivity was detected. In the Mo5, positive immunoreactivities specific for estrogen and androgen receptors were detected on the 5th and 20th postnatal days, respectively.Administration of 5a-dihydrotestosterone to female mice increased the number of motoneurones in the M05 to masculine proportions. By contrast, in male mice , treated with 17β-oestrogen, motoneurone numbers decreased to levels more typical of females. Treatment of cyproterone acetate , an androgen antagonist, significantly decreased the number of motoneurones in the Mo5 of immature male mice . Sensory neurones in the Me5 were unaffected by any of the treatment. Thus, androgenic and oestrogenic hormones are involved in the postnatal changes in motoneurone numbers of the Mo5, but not in the number of the Me5.