本文重新审视了支持“前兆”存在的分子证据,存在于脊椎动物中的尾部中脑区域(在小鼠中进行了研究)。据认为,它来自胚胎m2中胚层,并且似乎插在峡部(尾部)和下丘(头部)之间。在从艾伦发育和成年大脑Atlases检查的大量基因表达映射列表中,一些相当一致的选择性阳性标记,加上一些整齐的负面标记,在胚胎阶段E11.5,E13.5,E15.5,E18.5和几个出生后阶段一直到成年大脑。探索并说明了该横向区域的鼻翼和基底子域。有人认为,前峡的特殊分子和结构特征是由于其位置与峡部组织者相邻,在胚胎早期阶段必须存在高水平的FGF8和WNT1形态发生原。在这种情况下讨论了中脑的等位模式。对峡部形态发生素的影响的研究通常不涉及很大程度上未知的前复合体。证实了前鼻梁的成年鼻翼衍生物包含导水管周围灰色的特定前鼻翼,以经典楔形核为代表的中间地层,和包含臂下核的浅层。基础衍生物,占据插入动眼神经和滑车运动核之间的狭窄的回音域,包括多巴胺能和5-羟色胺能神经元,以及各种肽能神经元类型。
This essay reexamines molecular evidence supporting the existence of the \'preisthmus\', a caudal midbrain domain present in vertebrates (studied here in the mouse). It is thought to derive from the embryonic m2 mesomere and appears intercalated between the isthmus (caudally) and the inferior colliculus (rostrally). Among a substantial list of gene expression mappings examined from the Allen Developing and Adult Brain Atlases, a number of quite consistent selective positive markers, plus some neatly negative markers, were followed across embryonic stages E11.5, E13.5, E15.5, E18.5, and several postnatal stages up to the adult brain. Both alar and basal subdomains of this transverse territory were explored and illustrated. It is argued that the peculiar molecular and structural profile of the preisthmus is due to its position as rostrally adjacent to the isthmic organizer, where high levels of both FGF8 and WNT1 morphogens must exist at early embryonic stages. Isthmic patterning of the midbrain is discussed in this context. Studies of the effects of the isthmic morphogens usually do not attend to the largely unknown preisthmic complex. The adult alar derivatives of the preisthmus were confirmed to comprise a specific preisthmic sector of the periaqueductal gray, an intermediate stratum represented by the classic cuneiform nucleus, and a superficial stratum containing the subbrachial nucleus. The basal derivatives, occupying a narrow retrorubral domain intercalated between the oculomotor and trochlear motor nuclei, include dopaminergic and serotonergic neurons, as well as a variety of peptidergic neuron types.