Comparative Studies of Brain Development

Acomys cahirinus (the "spiny mouse")

Acomys (a mouse indigenous to the Sinai desert) is in the same evolutionary group as the lab rat or mouse (Muridae). The more common lab animals are born in a very immature state (they are "altricial", see the rat pup at left above) while Acomys is born with its ears and eyes open and easily moves about within hours of birth. It is rare when two closely related animals have such divergent developments. In a series of studies (listed below) we compared patterns of brain growth between these species. Since every evolutionary change occurs as a result of a modification in development, the work addressed both issues.

Brunjes, P. C. Olfactory bulb maturation in Acomys cahirinus: Is neural growth similar in precocial and altricial murids? Developmental Brain Research 8, 335-341, 1983.
Brunjes, P. C. Hippocampal maturation in the precocial murid rodent Acomys cahirinus. Brain, Behavior and Evolution 24, 58-74, 1984.
Brunjes, P. C. A stereological study of neocortical maturation in the precocial mouse Acomys cahirinus. Developmental Brain Research 19, 279-287, 1985.
Brunjes. P. C. Plasticity and precocity: Odor deprivation and brain development in the precocial mouse Acomys cahirinus. Neuroscience 24, 579-582, 1988.
Tessitore, C. T., & Brunjes, P. C. A comparative study of myelination in precocial and altricial murid rodents. Developmental Brain Research 43, 139-147, 1988.
Brunjes, P. C. A comparative study of prenatal development in the olfactory bulb, neocortex and hippocampal region of the precocial mouse Acomys cahirinus and the rat. Developmental Brain Research 49, 7-25, 1989.
Brunjes, P. C., Korol, D. L., and Stern, K. G. Prenatal neurogenesis in the telencephalon of the precocial mouse Acomys cahirinus. Neuroscience Letters 107, 114-119, 1989.
Brunjes, P. C. The precocial mouse Acomys cahirinus. Psychobiology 18, 339-350, 1990.

Monodelphis domestica (gray, short-tailed opposum)

Monodelphis domestica

Monodelphis (a Brazilian opossum), like most marsupials, gives birth after a very short gestation (13 days) to very immature pups (the neural tube closes in the telencephalic regions about 24 hours before birth). Unlike other marsupials Monodelphis has no pouch: pups simply find a nipple on the mother's ventrum and firmly attach-- litters hang like grapes off of the the mother. As a result, they allow easy examination of very early stages of brain development. We took advantage of these features in the studies listed below.

Brunjes, P. C., Jazaeri, A. and Sutherland, M. J. Olfactory bulb organization and development in Monodelphis domestica (the grey, short-tailed opossum). Journal of Comparative Neurology 320, 544-554, 1992.
Philpot, B. D., Jazaeri, A. A., and Brunjes, P. C. The development of serotonergic projections to the olfactory bulb of Monodelphis domestica (the grey, short-tailed opossum). Developmental Brain Research, 77, 265-270, 1994.
Cummings, D., and Brunjes, P. C. Migrating luteinizing hormone-releasing hormone (LHRH) neurons and processes co-localize with a glial substrate that expresses S100. Developmental Brain Research 88, 148-157, 1995.
Philpot, B. D., Klintsova, A. Y., and Brunjes, P. C. Oligodendrocyte/myelin immunoreactivity in the developing olfactory system. Neuroscience 67 1009-1019, 1995.
Malun, D., and Brunjes, P. The development of olfactory glomeruli: temporal and spatial interactions between olfactory receptor axons and mitral cells in opossums and rats. Journal of Comparative Neurology 368 1-16, 1996.
Cummings, D., Malun, D., and Brunjes, P. The development of the anterior commissure in the grey, short-tailed opossum Monodelphis domestica: Midline extracellular space and glia coincide with early axon decussation. Journal of Neurobiology 32, 403-414, 1997.
Cummings, D. M., Knab, B. R., and Brunjes, P. C. The effects of unilateral olfactory deprivation on the developing opossum, Monodelphis domestica. Journal of. Neurobiology 33, 429-438, 1997.
Couper-Leo, J., and Brunjes, P. C. Developmental analysis of the peripheral olfactory organ of the opossum Monodelphis domestica. Developmental Brain Research 114, 43-48, 1999.

Monodelphis pups

FISH

fish

Fish are the most abundant and diverse of the vertebrates. In two sets of studies we examined several aspects of the development of their olfactory systems, including the ability of their olfactory nerves to regenerate after being cut and the early expression of the genes used to code olfactory receptors.

Goldfish

Stewart, J. S., and Brunjes, P. C. Olfactory bulb and sensory epithelium in goldfish: morphological alterations accompanying growth. Developmental Brain Research 54, 187-194, 1990.
Stewart, J. S., and Brunjes, P. C. Spatial organization and plasticity of the primary and secondary olfactory projections in goldfish. Brain Research 628, 243-253, 1993.

Zebrafish

Byrd, C. A., and Brunjes, P. C. Organization of the olfactory system in adult zebrafish: histological, immunohistochemical and quantitative analyses. Journal of Comparative Neurology. 358 247-259, 1995.
Byrd, C. A,, Jones, J. T.., Quattro, J. M., Rogers, M. E., Brunjes, P. C., and Vogt, R. G. Ontogeny of odorant receptor gene expression in zebrafish, Danio rerio. Journal of Neurobiology 29 445-458, 1996.
Byrd, C.A., Brunjes,P.C. Addition of new cells to the olfactory bulb of adult zebrafish Ann. NY Acad. Sci. 855:274-276 , 1998.
Poling, K. R., and Brunjes, P. C., Sensory deafferentation and olfactory bulb morphology in the zebrafish and related species. Brain Research, 21, 135-141, 2000.

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