Abstract

JARAMILLO, Jenny et al. Histology and morphometry of dorsal root ganglia and their neurons in a fish of indeterminate growth the White Cachama (Piaractus brachypomus). Actu Biol [online]. 2009, vol.31, n.90, pp.43-52. ISSN 0304-3584.

A histological and morphometric analysis of the Dorsal Root Ganglia (DRGs) and their sensorial neurons were carried out to contribute to the understanding of how do their nervous system adapt to their fast body growth. Two age group of fish (age 1 = 20 dph; age 2 = 30 dph), and three spinal sections were used (anterior, middle, and posterior). Histologically, the DRGs and their sensorial neurons are similar to those described for mammals, birds, amphibians, and reptiles. On the other hand, the DRGs and their neurons are larger in age group 2 fish compared with age group 1 fish. There were also differences in the DRGs spinal sections in volume and number of neurons, and the sensorial neurons differed in area. The distribution of the types A and B subpopulations was 36 and 64%, respectively for age group 1 fish; and 25 and 75%, respectively for age group 2 fish. The differences between the DRGs and their sensorial neurons can be attributed to the proportion of target tissue (muscular, cutaneous, and visceral) that each of the DRGs and their neurons must innervate depending on their location. In these species, even a small increment in body mass, represents a change in DRGs and their sensory neurons, suggesting that White Cachama is a good model for the study of the adaptation of the nervous system to large changes in body size.

Keywords : dorsal root ganglion; indeterminate growth; morphometry; Piaractus brachypomus; sensory neurons.

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