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Clonal mixing, clonal restriction, and specification of cell types in the developing rat olfactory bulb
1Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
The Journal of Comparative Neurology
|March 13, 1999
Summary
Olfactory bulb progenitor cells show limited migration to other brain regions. Most clones contained a single cell type, but some multipotent progenitors existed before the rostral migratory stream formed.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Understanding the cellular origins and relationships within the olfactory bulb (OB) is crucial for comprehending its development and function.
- Investigating progenitor cell behavior provides insights into neural lineage and differentiation pathways.
Purpose of the Study:
- To elucidate the clonal relationships and migratory potential of olfactory bulb progenitor cells.
- To determine the degree of multipotency in OB progenitors at different developmental stages.
Main Methods:
- Retroviral labeling of olfactory bulb progenitor cells at embryonic days 14, 15, and 17.
- Analysis of clonal progeny distribution and cell types at postnatal days 10-15 using polymerase chain reaction (PCR) and DNA amplification.
- Distinguishing sibling relationships based on unique retroviral sequences.
Main Results:
- Clonal progeny were widely dispersed within the olfactory bulb but showed no significant migration to the neocortex.
- Occasional clonal dispersion was observed between the OB and pyriform/hippocampal regions.
- The majority of clones (84%) comprised a single cell type, particularly after later embryonic injections, suggesting lineage restriction.
- Mixed clones (16%) containing multiple cell types demonstrated the presence of multipotent OB progenitors prior to the formation of the olfactory rostral migratory stream.
- Olfactory bulb glial cells were not labeled, indicating potentially distinct lineages or migratory paths compared to neurons.
Conclusions:
- A hierarchical cell lineage model is proposed, starting with multipotent progenitors that generate more restricted progenitors.
- The findings suggest that olfactory bulb development involves a combination of multipotent progenitors and lineage restriction, influenced by developmental timing.
- Distinct developmental trajectories for OB neurons and glia are indicated by the differential labeling results.