In situ hybridization analysis of cells expressing messenger RNAs (mRNAs) for the neurotrophins @entity2137 ( @entity2137 ), @entity2136 ( @entity2136 ) and @entity10862 ( @entity10862 ) and their high-affinity receptors ( @entity3249 , @entity10864 and @entity10865 ) in the @entity35 embryo revealed a complex but specific expression pattern for each of these mRNAs. For all mRNAs a developmentally regulated expression was seen in many different tissues. @entity2136 and @entity10862 mRNAs were expressed in the sensory epithelia of the cochlea and vestibule macula of the sacculus and utricle, and both @entity10864 and @entity10865 mRNA were expressed in the spiral and vestibule ganglia innervating these sensory structures. @entity2137 and @entity10862 mRNA were found in the iris, innervated by the sympathetic neurons of the superior cervical ganglion and sensory neurons from the trigeminal ganglion, which expressed both @entity3249 and @entity10865 mRNAs. Both @entity2137 and @entity10862 mRNAs were also expressed in other target fields of the trigeminal ganglion, the epithelium of the whisker follicles ( @entity10862 mRNA) and in the epithelium of the nose, tongue and jaw. @entity10862 mRNA was found in the cerebellar external granule layer and @entity10865 mRNA in the Purkinje layer of the cerebellar primordia. These sites of synthesis are consistent with a target-derived neurotrophic interaction for @entity2137 , @entity2136 and @entity10862 . However, in some cases mRNAs for both the neurotrophins and their high-affinity receptors were detected in the same tissue, including the dorsal root, geniculate, superior, jugular, petrose and nodose ganglia, as well as in the hippocampus, frontal cortical plate and pineal recess, implying a local mode of action. Combined, these data suggest a broad function for the neurotrophins and their receptors in supporting neural innervation during embryonic development. The results also identify several novel neuronal systems that are likely to depend on the neurotrophins in vivo.

Cells Expressing mRNA for Neurotrophins and their Receptors During Embryonic XXXX Development.

@entity2136 :: ('24225(Tax:10116)', 'Gene') :: ['BDNF', 'brain-derived neurotrophic factor'] @entity2137 :: ('310738(Tax:10116)', 'Gene') :: ['NGF', 'nerve growth factor'] @entity10865 :: ('29613(Tax:10116)', 'Gene') :: ['trkC'] @entity3249 :: ('59109(Tax:10116)', 'Gene') :: ['trk'] @entity10862 :: ('81737(Tax:10116)', 'Gene') :: ['NT-3', 'neurotrophin-3'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity10864 :: ('25054(Tax:10116)', 'Gene') :: ['trkB']
@entity35 :: (10116,Species) :: ['Rat']
