Myelination in the Chorda Tympani of the Postnatal Rat: A Quantitative Electron Microscope Study

Ferrell, Fay; Tsuetaki, Tracy K.; Chole, Richard A.

doi:10.1159/000146006

Cited by 13 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…No muscles were cut. The chorda tympani is still undergoing the process of myelinization at this age (Ferrell et al, 1985) and is delicate, and difficult to locate, thereby necessitating an alternative surgical approach. Since the rat chorda tympani has its origin in the facial nerve canal (Green 19551, about a 6 mm length of facial nerve was evulsed (n = 4) as it exited the adjacent stylomastoid foramen.…”

Section: Methodsmentioning

confidence: 99%

“…Surgery was performed in the fifth postnatal week, after weaning was complete. This relatively young prepubertal age may highlight a critical taste bud-neural dependency or, conversely, optimize the potential for plasticity and regenerative capacity since gustatory system maturation progresses gradually over the first 90 postnatal days in rats (e.g., Farbman, 1965;Ferrell et al, 1981Ferrell et al, , 1985Hill and Almli, 1980;Mistretta, 1972;Yamada, 1980). Furthermore, criteria for bud counting did not rely exclusively on the presence of a taste pore.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Long‐term effects of gustatory neurectomy on fungiform papillae in the young rat

Ganchrow

1989

Anat. Rec.

View full text Add to dashboard Cite

Recent evidence from mature hamster fungiform papillae indicates that following denervation taste buds are present from 21 to 330 days in the absence of discernible intragemmal nerve fibers. In contrast, most prior taste bud degeneration studies focused on shorter survival times. The present inquiry in young rats examined the issue of postneurectomy buds, in which regeneration of the resected chorda tympani or facial nerves was prevented and anterior tongue tissue examined over a range of relatively long survival times (30-90 days). Conditions for observing potential taste buds used three histologic stains and a definition of the taste bud not necessarily requiring pore identification. In each case, serial section examination of the anterior-most 2-3 mm of lingual epithelium revealed 29-56 bud-containing fungiform papillae on the unoperated side. In contrast, ipsilateral to the neurectomy, only zero-7 medially-placed, mature-looking buds were observed per case, as well as zero-3 more laterally situated fungiform papillae containing small clusters of cells in basal epithelium that lacked the vertical organization and cytoplasmic staining intensity of mature taste buds. These cell aggregates were distributed evenly across survival time and stain used. Therefore, in young rats following gustatory neurectomy, longer survival times, per se, would not appear to be a prerequisite for sustaining fungiform taste buds. The appearance of "midline" buds postsurgery may be attributed to either normal contralateral or a net bilateral innervation, and/or ipsilateral denervation and bud loss inducing neural sprouting from the contralateral side.

show abstract

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Long‐term effects of gustatory neurectomy on fungiform papillae in the young rat

Ganchrow

1989

Anat. Rec.

View full text Add to dashboard Cite

show abstract

“…The maturation of the rNST IPSPs is just one of many other developmental changes that occur in the developing taste system during the first postnatal weeks. For example the chorda tympani nerve becomes increasingly myelinated (Ferrell et al 1985), and both the chorda tympani and glossopharyngeal nerves enter the NST and continue to develop until P45 (Lasiter 1992). There is a rapid period of growth of first-and second-order dendrites of rNST elongate and ovoid neurons from P6 to P20, and the first-order dendrites of multipolar cells continue to increase in length up to at least P70 .…”

Section: Functional Significancementioning

confidence: 99%

Postnatal Development of Inhibitory Synaptic Transmission in the Rostral Nucleus of the Solitary Tract

Grabauskas

Bradley

2001

Journal of Neurophysiology

View full text Add to dashboard Cite

To explore the postnatal development of inhibitory synaptic activity in the rostral (gustatory) nucleus of the solitary tract (rNST), whole cell and gramicidin perforated patch-clamp recordings were made in five age groups of rats [postnatal day 0-7 (P0-7), P8-14, P15-21, P22-30, and P >55]. The passive membrane properties of the developing rNST neurons as well as the electrophysiological and pharmacological characteristics of single and tetanic stimulus-evoked inhibitory postsynaptic potentials (IPSPs) were studied in brain slices under glutamate receptor blockade. During the first postnatal weeks, significant changes in resting membrane potential, spontaneous activity, input resistance, and neuron membrane time constant of the rNST neurons occurred. Although all the IPSPs recorded were hyperpolarizing, the rise and decay time constants of the single stimulus shock-evoked IPSPs decreased, and the inhibition response-concentration function to the gamma-aminobutyric acid (GABA) receptor antagonist bicuculline methiodide (BMI) shifted to the left during development. In P0-7 and P8-14, but not in older animals, the IPSPs had a BMI-insensitive component that was sensitive to block by picrotoxin, suggesting a transient expression of GABA(C) receptors. Tetanic stimulation resulted in both short- and long-term changes of inhibitory synaptic transmission in the rNST. For P0-7 and P8-14 animals tetanic stimulation resulted in a sustained hyperpolarization that was maintained for some time after termination of the tetanic stimulation. In contrast, tetanic stimulation of neurons in P15-21 and older animals resulted in hyperpolarization that was not sustained but decayed back to a more positive level with an exponential time course. Tetanic stimulation resulted in potentiation of single stimulus shock-evoked IPSPs in ~50% of neurons in all age groups. These developmental changes in inhibitory synaptic transmission in the rNST may play an important role in shaping synaptic activity in early development of the rat gustatory system during a time of maturation of taste preferences and aversions.

show abstract

“…That is, the differential amount of neurotrophic factors produced may support corresponding numbers of innervating ganglion cells, even at maturity. Although this implies that differential numbers of ganglion cells innervating a specific taste bud may be maintained, depending on the amount of neurotrophic factors produced by that taste bud, the total number of neurons available to innervate all taste buds probably do not change during the ages studied here (Ferrell et al, 1985).…”

Section: Discussionmentioning

confidence: 85%

Neuron/target matching between chorda tympani neurons and taste buds during postnatal rat development

Krimm

Hill

2000

J. Neurobiol.

View full text Add to dashboard Cite

During postnatal development, a relationship is established between the size of individual taste buds and number of innervating neurons. To determine whether rearrangement of neurons that innervate taste buds establishes this relationship, we labeled single taste buds at postnatal day 10 (P10) and again at either P15, P20, or P40 with retrograde fluorescent neuronal tracers. The number of single‐ and double‐labeled geniculate ganglion cells was counted, and the respective taste bud volumes were measured for the three groups of rats. The current study replicates findings from an earlier report demonstrating that the larger the taste bud, the more geniculate ganglion cells that innervate it. This relationship between taste bud size and number of innervating neurons is not apparent until P40, when taste bud size reaches maturity. These findings are extended here by demonstrating that the number of neurons that innervate taste buds at P10, when taste bud size is small and relatively homogeneous, predicts the size that the respective taste bud will become at maturity. Moreover, while there is some neural rearrangement of taste bud innervation from P10 to P40, rearrangement does not impact the relationship between taste bud size and innervating neurons. That is, the neurons that maintain contact with taste buds from P10 through P40 accurately predict the mature taste bud size. Therefore, the size of the mature taste bud is determined by P10 and relates to the number of sensory neurons that innervate it at that age and the number of neurons that maintain contact with it throughout the first 40 days of postnatal development. © 2000 John Wiley & Sons, Inc. J Neurobiol 43: 98–106, 2000

show abstract

Myelination in the Chorda Tympani of the Postnatal Rat: A Quantitative Electron Microscope Study

Cited by 13 publications

References 14 publications

Long‐term effects of gustatory neurectomy on fungiform papillae in the young rat

Long‐term effects of gustatory neurectomy on fungiform papillae in the young rat

Postnatal Development of Inhibitory Synaptic Transmission in the Rostral Nucleus of the Solitary Tract

Neuron/target matching between chorda tympani neurons and taste buds during postnatal rat development

Contact Info

Product

Resources

About