Summary
The North American opossum is born 12 days after conception and is therefore available for experimental manipulation in an immature state. We have used the opossum to study the growth of cortical axons into the brainstem and spinal cord and have obtained evidence that such growth occurs in an orderly fashion. Cortical axons reach the ventral mesencephalon 12 days after birth and some of them have grown into the caudal medulla where they decussate by 23 days. At the latter stage immature cortical axons also distribute to the midbrain tegmentum, the basilar pons, the inferior olive and the hilum of the nucleus cuneatus. Cortical axons first enter the spinal cord about 30 days after birth where they are present in the white matter before growing into the dorsal horn. The forelimb placing reaction does not develop until well after cortical axons have reached cervical levels. Axons from the cerebral cortex grow into the spinal cord before there is evidence for cortical innervation of either the red nucleus or the bulbar reticular formation and well before pyramidal cells of the neocortex are mature. The relatively late development of corticospinal and corticobulbar systems contrasts markedly with the early growth of bulbospinal axons.
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References
Bautista NA, Matzke HA (1965) A degeneration study of the course and extent of pyramidal tract of the opossum. J Comp Neurol 124:367–376
Bromily RB, Brooks C McC (1940) Role of neocortex in regulating postural reactions of the opossum (Didelphis virginiana). J Neurophysiol 3: 339–346
Cabana T, Martin GF (1980) The origin of brainstem projections to the thoracic cord at different stages of development in the North American opossum. Soc Neurosci Abst 6:649
Crutcher KA, Humbertson AO, Martin GF (1978) The origin of brainstem-spinal pathways in the North American opossum (Didelphis virginiana). Studies using the horseradish peroxidase method. J Comp Neurol 179:160–194
Cutts JH, Krause WJ, Leeson CR (1978) General observations on the growth and development of the young pouch opossum, Didelphis virginiana. Biol the Neonate 33:264–272
DeMeyer W (1967) Ontogenesis of the rat corticospinal tract. Arch Neurol Paris 16:203–211
Dom R, Falls W, Martin GF (1973) The motor nucleus of the facial nerve in the opossum (Didelphis marsupialis virginiana). Its organization and connections. J Comp Neurol 152:373–402
Donatelle JM (1977) Growth of the corticospinal tract and the development of placing reactions in the postnatal rat. J Comp Neurol 175:207–232
Fink RP, Heimer L (1967) Two methods for selective silver impregnation of degenerating axons and their synaptic endings in the central nervous system. Brain Res 4:369–374
Gilbert M, Stelzner D (1979) The development of descending and dorsal root connections in the lumbosacral spinal cord of the postnatal rat. J Comp Neurol 184:821–838
Gray PA (1924) The cortical lamination patterns of the opossum, Didelphis virginiana. J Comp Neurol 37:221–263
Hicks SP, D'Amato CJ (1970) Motor-sensory cortex-corticospinal system and developing locomotion and placing in rats. Am J Anat 143:1–42
Hostege G, Kuypers HGJM (1977) Propriobulbar fibre connections to the trigeminal, facial, and hypoglossal motor nuclei. I. An anterograde degeneration study in the cat. Brain 100:239–264
Humbertson AO, Martin GF (1979) The development of monoaminergic brainstem-spinal systems in the North American opossum. Anat Embryol 156:301–318
Humphrey T (1960) The development of the pyramidal tracts in human fetuses correlated with cortical differentiation. Soc Int Meet Neurol, Amsterdam 93–103
Langworthy OR (1927) Correlated physiological and morphological studies of the development of electrically responsive areas in the cerebral cortex of the opossum. Contrib Embryol, Carnegie Inst Wash 19:149–175
Lende RA (1963) Motor representation in the cerebral cortex of the opossum (Didelphis virginiana). J Comp Neurol 121:405–415
Leonard CM (1973) A method for assessing stages of neuronal maturation. Brain Res 53:412–416
Leonard CM (1974) Degenerating argyrophilia as an index of neuronal maturation: Studies on the optic tract of the golden hamster. J Comp Neurol 156:435–458
Leonard CM (1975) Developmental changes in olfactory bulb projections revealed by degeneration argyrophilia. J Comp Neurol 162:467–486
Lund RD, Mustari MJ (1977) Development of the geniculocortical pathway in rats. J Comp Neurol 173:289–305
Martin GF (1968) The pattern of neocortical projections to the mesencephalon of the opossum, Didelphis virginiana. Brain Res 11:593–610
Martin GF, Fisher AM (1968) A further evaluation of the origin, the course and the termination of the opossum corticospinal tract. J Neurol Sci 7:177–187
Martin GF, Beattie MS, Bresnahan JC, Henkel CK, Hughes HC (1975a) Cortical and brain stem projections to the spinal cord of the American opossum (Didelphis marsupialis virginiana). Brain Behav Evol 12:270–310
Martin GF, Bresnahan JC, Henkel CK, Megirian D (1975b) Corticobulbar fibers in the North American opossum (Didelphis marsupialis virginiana) with notes on the Tasmanian brush-tailed possum (Trichosurus vulpecula) and other marsupials. J Anat (London) 120:439–484
Martin GF, Beals JK, Culberson JL, Dom R, Goode G, Humbertson AO (1978) Observations on the development of brainstem-spinal systems in the North American opossum. J Comp Neurol 181:271–290
Martin GF, Culberson JL, Tschismadia I (1980) The development of major projections to the inferior olivary nucleus. Experimental studies using the North American opossum Anat Embryol 160:187–202
Morest DK (1970) A study of neurogenesis in the forebrain of opossum pouch young. Z Anat Entwickl Gesch 130:265–305
Panneton WM, Martin GF (1979) Midbrain projections to the trigeminal, facial and hypoglossal nuclei in the opossum. A study using axonal transport techniques. Brain Res 168:493–511
Rakic P (1977) Prenatal development of the visual system in rhesus monkey. Phil Trans R Soc Ser B 278:245–260
Schneider GE (1969) Two visual systems. Science 163:895–902
Turner EL (1924) The pyramidal tract of the virginian opossum (Didelphis virginiana). J Comp Neurol 36:387–397
Ulinski PS (1971) External morphology of pouch young opossum brains: A profile of opossum neurogenesis. J Comp Neurol 142:33–58
Vaughn JE, Hendrickson CK Grieshaber JH (1974) A quantitative study of synapses on motor neuron dendritic growth cones in developing mouse spinal cord. J Cell Biol 60:664–672
Ward J (1954) The development of the cortico-spinal tract in the pouch young of the opossum. J Comp Neurol 101:483–494
Weed LH, Langworthy OR (1925) Developmental study of excitatory areas in the cerebral cortex of the opossum. Am J Physiol 72:8–24
Wise SP, Jones EG (1976) Organization and postnatal development of the commissural projections of the rat somatic sensory cortex. J Comp Neurol 168:313–343
Wise SP, Hendry SHC, Jones EG (1977) Prenatal development of sensory-motor cortical projections in cats. Brain Res 138:538–544
Wise SP, Fleshman JW, Jones EG (1979) Maturation of pyramidal cell form in relation to developing afferent and efferent connections of rat somatic sensory cortex. Neuroscience 4:1275–1297
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This investigation was supported by NS-07410 and BNS-8008675 as well as the WVa Medical Corporation
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Martin, G.F., Cabana, T., Culberson, J.L. et al. The early development of corticobulbar and corticospinal systems. Anat Embryol 161, 197–213 (1980). https://doi.org/10.1007/BF00305344
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DOI: https://doi.org/10.1007/BF00305344