title: Changes in somatodendritic morphometry of rat oculomotor nucleus motoneurons during postnatal development.
abstract: This work investigates the somatodendritic shaping of rat oculomotor nucleus motoneurons (Mns) during postnatal development. The Mns were functionally identified in slice preparation, intracellularly injected with neurobiotin, and three-dimensionally reconstructed. Most of the Mns (approximately 85%) were multipolar and the rest (approximately 15%) bipolar. Forty multipolar Mns were studied and grouped as follows: 1-5, 6-10, 11-15, and 21-30 postnatal days. Two phases were distinguished during postnatal development (P1-P10 and P11-P30). During the first phase, there was a progressive increase in the dendritic complexity; e.g., the number of terminals per neuron increased from 26.3 (P1-P5) to 47.7 (P6-P10) and membrane somatodendritic area from 11,289.9 microm(2) (P1-P5) to 19,235.8 microm(2) (P6-P10). In addition, a few cases of tracer coupling were observed. During the second phase, dendritic elongation took place; e.g., the maximum dendritic length increased from 486.7 microm (P6-P10) to 729.5 microm in adult Mns, with a simplification of dendritic complexity to values near those for the newborn, and a slow, progressive increase in membrane area from 19,235.8 microm(2) (P6-P10) to 24,700.3 microm(2) (P21-P30), while the somatic area remained constant. In conclusion, the electrophysiological changes reported in these Mns with maturation (Carrascal et al. [2006] Neuroscience 140:1223-1237) cannot be fully explained by morphometric variations; the dendritic elongation and increase in dendritic area are features shared with other pools of Mns, whereas changes in dendritic complexity depend on each population; the first phase paralleled the establishment of vestibular circuitry and the second paralleled eyelid opening.
authors.affiliation: Department of Physiology and Zoology, University of Seville, 41012 Seville, Spain.
authors.forename: Livia
authors.initials: L
authors.lastname: Carrascal
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Nieto-Gonzalez
authors.forename: Blas
authors.initials: B
authors.lastname: Torres
authors.forename: Pedro
authors.initials: P
authors.lastname: Nunez-Abades
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D001933:Brain Stem / Q000166:cytology* / Q000254:growth & development*; D003712:Dendrites / Q000502:physiology*; D005260:Female; D021621:Imaging, Three-Dimensional / Q000379:methods; D066298:In Vitro Techniques; D008297:Male; D008953:Models, Anatomic; D009046:Motor Neurons / Q000166:cytology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009802:Oculomotor Nerve / Q000254:growth & development*; D051381:Rats; D017208:Rats, Wistar
chemical_list: C070614:neurobiotin; D001710:Biotin