Gilland E, Straka H, Wong T W, Baker R, Zottoli S J
Department of Physiology and Neuroscience, New York University Medical Center, New York, New York, 10016; Marine Biological Laboratory, Woods Hole, Massachusetts, 02543; Department of Anatomy, Howard University College of Medicine, Washington, DC, 20059.
J Comp Neurol. 2014 Jul 1;522(10):2446-64. doi: 10.1002/cne.23544.
The vertebrate hindbrain develops as a series of well-defined neuroepithelial segments or rhombomeres. While rhombomeres are visible in all vertebrate embryos, generally there is not any visible segmental anatomy in the brains of adults. Teleost fish are exceptional in retaining a rhombomeric pattern of reticulospinal neurons through embryonic, larval, and adult periods. We use this feature to map more precisely the segmental imprint in the reticular and motor basal hindbrain of adult goldfish. Analysis of serial sections cut in three planes and computer reconstructions of retrogradely labeled reticulospinal neurons yielded a segmental framework compatible with previous reports and more amenable to correlation with surrounding neuronal features. Cranial nerve motoneurons and octavolateral efferent neurons were aligned to the reticulospinal scaffold by mapping neurons immunopositive for choline acetyltransferase or retrogradely labeled from cranial nerve roots. The mapping corresponded well with the known ontogeny of these neurons and helps confirm the segmental territories defined by reticulospinal anatomy. Because both the reticulospinal and the motoneuronal segmental patterns persist in the hindbrain of adult goldfish, we hypothesize that a permanent "hindbrain framework" may be a general property that is retained in adult vertebrates. The establishment of a relationship between individual segments and neuronal phenotypes provides a convenient method for future studies that combine form, physiology, and function in adult vertebrates.
脊椎动物的后脑发育为一系列界限分明的神经上皮节段或菱脑节。虽然菱脑节在所有脊椎动物胚胎中都可见，但在成年动物的大脑中通常没有任何可见的节段性解剖结构。硬骨鱼是例外，它们在胚胎期、幼体期和成体期都保留着网状脊髓神经元的菱脑节模式。我们利用这一特征更精确地绘制成年金鱼网状和运动性基底后脑的节段印记。对在三个平面上切割的连续切片进行分析，并对逆行标记的网状脊髓神经元进行计算机重建，得到了一个与先前报道相符且更便于与周围神经元特征进行关联的节段框架。通过对胆碱乙酰转移酶免疫阳性或从颅神经根逆行标记的神经元进行定位，将脑神经运动神经元和八分体外侧传出神经元与网状脊髓支架对齐。这种定位与这些神经元已知的个体发生过程非常吻合，并有助于确认由网状脊髓解剖结构定义的节段区域。由于网状脊髓和运动神经元的节段模式在成年金鱼的后脑中都持续存在，我们推测一个永久性的“后脑框架”可能是成年脊椎动物普遍保留的特性。在个体节段与神经元表型之间建立关系，为未来结合成年脊椎动物的形态、生理和功能的研究提供了一种便捷的方法。
