Organization of hindbrain segments in the zebrafish embryo

The dorsal hindbrain includes distinct classes of neurons for processing various sensory stimuli, but the developmental aspects of these neurons remain largely unknown. We identify here two distinct classes of neurons in the dorsal hindbrain of developing zebrafish: (1) neurons that express the inhibitory neuronal marker Gad1/2, and (2) neurons that express the zn-5 antigen and Lhx2/9 and require the basic helix-loop-helix transcription factor Atoh1a for development. Neurons were traced to their axon terminals by expressing green fluorescent protein using the Gal4VP16-UAS (UAS, upstream activating sequences) system in combination with the promoter/enhancer regions of gad2 for the Gad1/2(؉) neurons and zic1 for the zn-5(؉)Lhx2/9(؉) neurons. The Gad1/2(؉) neurons projected to the contralateral hindbrain, while the zn-5(؉)Lhx2/9(؉) neurons projected to the contralateral midbrain torus semicircularis, suggesting a role in auditory and lateral line sensory processing. Comparison of these projections with those from the cochlear nuclei to the inferior colliculus in mammals suggests similarities across vertebrate species. Developmental Dynamics 236:706 -718, 2007.

Section: Two Distinct Classes Of Neurons In the Dorsal Hindbrain Basementioning

confidence: 84%

Section: Gad1/2(؉) Neurons Project To the Contralateral Hindbrainmentioning

confidence: 99%

Visualization of two distinct classes of neurons by gad2 and zic1 promoter/enhancer elements in the dorsal hindbrain of developing zebrafish reveals neuronal connectivity related to the auditory and lateral line systems

Sassa

Aizawa

Okamoto

2007

“…Hindbrain neuroanatomy corresponds with morphological segmentation ( Fig. 3; Hanneman et al, 1988;Lumsden and Keynes, 1989;Trevarrow et al, 1990). This correspondence, although true of many neuronal types, is most dramatically illustrated by the individually identified reticulospinal interneurons of the zebrafish.…”

Section: Principles Of Hindbrain Developmentmentioning

confidence: 89%

Constructing the hindbrain: Insights from the zebrafish

Moens¹,

Prince²

2002

197

179

The hindbrain is responsible for controlling essential functions such as respiration and heart beat that we literally do not think about most of the time. In addition, cranial nerves projecting from the hindbrain control muscles in the jaw, eye, and face, and receive sensory input from these same areas. In all vertebrates that have been studied, the hindbrain passes through a segmented phase shortly after the neural tube has formed, with a series of seven bulges-the rhombomeres-forming along the anterior-posterior extent of the neural tube. Our current understanding of vertebrate hindbrain development comes from integrating data from several model systems. Work on the chick has helped us to understand the cell biology of the rhombomeres, whereas the power of mouse molecular genetics has allowed investigation of the molecular mechanisms underlying their development. This review focuses on the special insights that the zebrafish system has provided to our understanding of hindbrain development. As we will discuss, work in the zebrafish has elucidated inductive events that specify the presumptive hindbrain domain and has identified genes required for hindbrain segmentation and the specification of segment identities.

“…1), because the array of genetic, genomic, molecular, and embryologic tools available in these organisms holds great promise for elucidating the mechanisms underlying the development of these neurons and their axonal projections. Figure 1 and the following text are based upon data or adapted from figures in the following studies: zebrafish (Kimmel et al, 1985;Hatta et al, 1990;Trevarrow et al, 1990;Chandrasekhar et al, 1997;Schilling and Kimmel, 1997;Higashijima et al, 2000); chick (Lumsden and Keynes, 1989;Simon and Lumsden, 1993;Gilland and Baker, 1993;Simon et al, 1994;Fritzsch, 1996;Lumsden and Krumlauf, 1996;Jacob and Guthrie, 2000); mouse (Carpenter et al, 1993;Gilland and Baker, 1993;Fritzsch, 1996;Studer et al, 1996;SchneiderMaunoury et al, 1997;Garel et al, 2000;Studer, 2001). The neuroanatomy described below is limited to observations up to specific embryonic stages (Fig.…”

Section: Organization Of Bmns and Other Hindbrain Efferent Neuronsmentioning

confidence: 99%

Turning heads: Development of vertebrate branchiomotor neurons

Chandrasekhar

2003

164

204

The cranial motor neurons innervate muscles that control eye, jaw, and facial movements of the vertebrate head and parasympathetic neurons that innervate certain glands and organs. These efferent neurons develop at characteristic locations in the brainstem, and their axons exit the neural tube in well-defined trajectories to innervate target tissues. This review is focused on a subset of cranial motor neurons called the branchiomotor neurons, which innervate muscles derived from the branchial (pharyngeal) arches. First, the organization of the branchiomotor pathways in zebrafish, chick, and mouse embryos will be compared, and the underlying axon guidance mechanisms will be addressed. Next, the molecular mechanisms that generate branchiomotor neurons and specify their identities will be discussed. Finally, the caudally directed or tangential migration of facial branchiomotor neurons will be examined. Given the advances in the characterization and analysis of vertebrate genomes, we can expect rapid progress in elucidating the cellular and molecular mechanisms underlying the development of these vital neuronal networks.