Previous experiments in Xenopus laevis have shown that transplantation of an olfactory placode can result in the connection of the transplanted olfactory placode with different portions of the brain where hypertrophy and hyperplasia occurs. This project intended to ascertain the morphological interactions of the olfactory placode with the central nervous system and to compare this with the interaction of the eye primordium with the CNS in young embryos of Xenopus. Normal development of the olfactory placode was also studied to describe the morphological sequence of events involved in the development of the olfactory placode. / The olfactory placode and optic vesicle of two different species of Xenopus(laevis and borealis) were transplanted between the species at stage 23 to exploit the differential nuclear straining with quinacrine of Xenopus borealis. The chimerae enabled us to recognize where the donor cells are located among the host cells. / The olfactory organ first appears at stage 23 as a paired thickening of the two ectodermal layers: the superficial non-nervous layer (NNL) and the inner nervous layer (NL). Receptor cells differentiate from the NL and the supporting cells develop from the NNL. Sensory axons reach the brain at stage 32. Primitive synaptic contacts first appear at stage 37/38. / The transplanted placode in place of the removed eye usually fuses with the host's ipsilateral olfactory placode producing a large and irregularly shaped olfactory organ. With the passage of time the cells of the fused olfactory placode acquire a staining pattern that is entirely characteristic of the host. From the transplanted placode a nerve develops and reaches the diencephalon which is not its normal target or at times the telencephalon. Many placodal cells migrate along this nerve and penetrate the brain. These cells form small aggregates in the host brain. The donor cells remain in the host CNS up to premetamorphic stages when my experiments terminated. / The eye transplanted in place of the excised olfactory placode develops well with all the retinal layers and lens, however, it grows into a large, irregular organ. From the eye transplant, a cellular bridge develops and specifically connects with the diencephalon which is its normal target. The cellular bridge consists of donor cells and fibers. Some of the donor cells penetrate the rostral diencephalon mixing with the host cells. / The transplanted olfactory placode shows plasticity in that it connects with unconventional targets. Many cells from the transplanted olfactory placode migrate and incorporate into the non-olfactory area of the host brain. As opposed to the olfactory organ, the transplanted eye specifically reaches its normal target in spite of the two host eyes. The retinal cells that migrate through the tissue bridge incorporate into the host diencephalon. / Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3752. / Major Professor: Pasquale P. C. Graziadei. / Thesis (Ph.D.)--The Florida State University, 1989.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78065 |
| Contributors | Kim, Hyeyoung., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 212 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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