Phenotypes Associated with This Genotype

Genotype
MGI:2175188

• Allelic Composition: Ntrk2^tm1Kln/Ntrk2^tm1Kln
• Genetic Background: involves: 129S1/Sv * 129X1/SvJ

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

nervous system

abnormal synapse morphology ( J:75365 )

• failure of synapse formation in vestibular sensory epithelia ; no fibers or synapses are seen in the canal epithelia and only small synaptic contacts or partial calyces are seen in the utricle or saccular epithelia, respectively

small vestibular ganglion ( J:49472 )

• vestibular ganglia are reduced in volume and cell number by about 25% at P7 and in adulthood, but not at birth

abnormal vestibulocochlear nerve morphology ( J:75365 )

• reduction in the diameter and area of the posterior vertical crista nerve

• posterior vertical crista nerve shows a reduction in size of individual fibers at P26 and P70

abnormal vestibular nerve morphology ( J:75365 )

• cell body sizes of vestibular neurons are modestly reduced; soma sizes at P7 and P70 are 21% and 27% smaller, respectively

• 25% reduction of NTRK2-dependent vestibular neurons at P7, the remaining 75% of vestibular neurons survive to adulthood

abnormal somatic sensory system morphology ( J:49472 , J:75365 )

• 30% of small diameter axons are missing in the saphenous nerve (J:49472)

• the aortic depressor nerve is reduced in size (J:75365)

abnormal sensory neuron innervation pattern ( J:75365 , J:84871 )

• vestibular neurons lose target innervation in adults (J:75365)

• at P8, but not at P0, mutants show a diminished density of fibers to all canal end organs and the utricle (J:75365)

• reduction in the number of myelinated fibers extending to the posterior vertical crista at P0 and reaching 30-40% at P26-P70 (J:75365)

• loss of baroreceptor innervation of the aortic arch (J:75365)

• defects in both afferent and efferent innervation of the vestibular sensory epithelium (J:84871)

decreased sensory neuron number ( J:75365 )

• 25% reduction of NTRK2-dependent vestibular neurons at P7 and in adulthood

small nodose ganglion ( J:49472 )

• 59% reduction in nodose neurons, primarily due to loss of NTF5 (NT4)-dependent neurons and not BDNF-dependent neurons

absent hair-down neurons ( J:49472 )

• loss of D-hair receptors

behavior/neurological

hyperactivity ( J:49472 )

hearing/vestibular/ear

abnormal inner ear vestibule morphology ( J:84871 )

• defects in both afferent and efferent innervation of the vestibular sensory epithelium