Restricted distribution of S-phase cells in the anterior subventricular zone of the postnatal mouse forebrain

Abstract

The anterior subventricular zone (SVZa) is the site for postnatal neurogenesis of interneurons of the olfactory bulb (OB). Concurrently or after proliferation, neuronal precursors therein migrate within it to reach the OB, an event known as the rostral migratory stream (RMS). We used bromodeoxyuridine (BrdU) incorporation with short survival times to investigate the distribution of S-phase nuclei in the SVZa/RMS of the postnatal mouse. We observed that they were distributed along a radial, outside-in, decreasing gradient that persisted until postnatal day 10 (P10), then faded away to finally disappear by P16. After longer post-injection survival times labeled cell distribution became homogeneous. GFAP-positive glia are present at the periphery but not at the core of the SVZa. Our results represent the first evidence of a discrete spatial organization of a cell cycle phase within the SVZ, and also suggests a segregation of proliferating and migrating cells in the rostral migratory stream of the early postnatal mouse.

Gap Junction-Mediated Coupling in the Postnatal Anterior Subventricular Zone

“…3C) than in the rostral parts ( fig. 3A, B), suggesting a caudal-to-rostral gradient of coupling similar to the proliferative pattern previously described in this layer [Menezes et al, 1998]. …”

“…The distribution of LY+/RD-cells was found to form a peculiar cap in the dorsal part of the SVZa ( fig. 3), also reminiscent of the distribution of S-phase cells described previously [Menezes et al, 1998]. The number of coupled cells forming this cap increased caudally, and extended deeper into the slice ( fig.…”

“…Although gap junctions have been previously detected in the SVZa by EM and immunohistochemical studies [Miragall et al, 1997[Miragall et al, , 1992Yamamoto et al, 1990], our data represent a strong indication of cell coupling mediated by gap junctions in situ within the SVZa. Moreover, the spatial distribution of cell coupling suggests that junctional communication may correlate functionally with an S-phase zone described recently [Menezes et al, 1998]. Thus, GJC may be related to cell proliferation and/or migration in the SVZa.…”

“…Takahashi et al, 1992]. The SVZa, on the other hand, is a thick cell layer with no sign of any typical interkinetic nuclear migration, despite a spatial segregation of S-phase cells [Menezes et al, 1998]. The peak of proliferation within the VZ takes place during embryogenesis, after which the layer re-gresses and transforms into the ependymal lining of the lateral ventricles.…”

Multiple Cell Populations in the Early Postnatal Subventricular Zone Take Distinct Migratory Pathways: A Dynamic Study of Glial and Neuronal Progenitor Migration

“…A preferential labeling of glial progenitors with a lower titer virus could arise if the glial progenitor population were larger than the neuronal progenitor population or cycled more rapidly, or if a larger proportion of glial progenitors were cycling at the time of viral injection. There is little direct evidence at present to support such potential differences, although Menezes et al (1998) noted that those cycling progenitors labeled with BrdU after short survival preferentially resided at the periphery of the SVZa, rather than in the central zone.…”