Jacquin M F, Rhoades R W
Brain Res. 1987 Feb;428(2):161-75. doi: 10.1016/0165-3806(87)90114-3.
At birth (gestational day 16), the hamster infraorbital nerve projects to the appropriate portion of the brainstem, though the projection lacks adult-like internal organization (patchiness). Infraorbital nerve damage at this time does not produce appreciable transganglionic atrophy in the central projections of the infraorbital nerve, but it does result in a failure to develop normal infraorbital primary afferent patches. Such damage also produces a more widespread central projection of spared mandibular afferents into regions occupied by 'regenerate' infraorbital terminals (J. Comp. Neurol., 235 (1985) 129-143). In the present study, transganglionic transport techniques were again used to show that, by postnatal day 5 (gestational day 21), rostrocaudally continuous aggregates of horseradish peroxidase-labelled infraorbital terminals are visible throughout the trigeminal brainstem nuclear complex. This aggregation pattern is nearly adult-like and isomorphic with the distribution of the mystacial vibrissae on the face. A similar infraorbital lesion performed on postnatal day 5, however, markedly decreased the density of the adult central projection of the infraorbital nerve to subnuclei principalis, oralis, interpolaris, and the magnocellular laminae of caudalis. The projection to superficial laminae of caudalis and the cervical dorsal horn was maintained. A postnatal-day-5 infraorbital lesion also failed to produce a more widespread central projection from spared mandibular primary afferents. These data suggest a relationship between the postnatal maturity of trigeminal primary afferents and the response of damaged and undamaged trigeminal afferents to infraorbital nerve transection in hamster. The similarity in the central primary afferent response to lesions at equivalent gestational times (postnatal days 5 and 0, respectively) in hamster and rat, suggests that this plasticity gradient may be a general characteristic of mammalian trigeminal primary afferents.
出生时（妊娠第16天），仓鼠眶下神经投射至脑干的相应部位，不过这种投射缺乏成年动物那样的内部组织结构（呈斑片状）。此时的眶下神经损伤不会在眶下神经的中枢投射中产生明显的跨节变性萎缩，但会导致眶下初级传入斑不能正常发育。这种损伤还会使未受损的下颌传入神经更广泛地向“再生”眶下终末所占据的区域进行中枢投射（《比较神经学杂志》，第235卷（1985年）第129 - 143页）。在本研究中，再次运用跨节运输技术来表明，到出生后第5天（妊娠第21天）时，在整个三叉神经脑干核复合体中可见到辣根过氧化物酶标记的眶下终末呈头尾连续的聚集。这种聚集模式近乎成年动物的模式，且与面部触须的分布同构。然而，在出生后第5天进行类似的眶下损伤，会显著降低眶下神经向三叉神经主核、口核、极间核以及尾侧大细胞层的成年中枢投射密度。向尾侧浅层和颈背角的投射得以保留。出生后第5天的眶下损伤也未能使未受损的下颌初级传入神经产生更广泛的中枢投射。这些数据表明仓鼠三叉神经初级传入神经的出生后成熟度与受损和未受损的三叉神经传入神经对眶下神经横断的反应之间存在关联。仓鼠和大鼠在等效妊娠时间（分别为出生后第5天和第0天）对损伤的中枢初级传入神经反应相似，这表明这种可塑性梯度可能是哺乳动物三叉神经初级传入神经的一个普遍特征。
