Mitotic Events in Cerebellar Granule Progenitor Cells That Expand Cerebellar Surface Area Are Critical for Normal Cerebellar Cortical Lamination in Mice

Abstract

Late embryonic and postnatal cerebellar folial surface area expansion promotes cerebellar cortical cytoarchitectural lamination. We developed a streamlined sampling scheme to generate unbiased estimates of murine cerebellar surface area and volume using stereological principles. We demonstrate that during the proliferative phase of the external granule layer (EGL) and folial surface area expansion, EGL thickness does not change and thus is a topological proxy for progenitor self-renewal. The topological constraints indicate that during proliferative phases, migration out of the EGL is balanced by self-renewal. Progenitor self-renewal must, therefore, include mitotic events yielding either 2 cells in the same layer to increase surface area (β-events) and mitotic events yielding 2 cells, with 1 cell in a superficial layer and 1 cell in a deeper layer (α-events). As the cerebellum grows, therefore, β-events lie upstream of α-events. Using a mathematical model constrained by the measurements of volume and surface area, we could quantify inter-mitotic times for β-events on a per-cell basis in post-natal mouse cerebellum. Furthermore, we found that loss of CCNA2, which decreases EGL proliferation and secondarily induces cerebellar cortical dyslamination, shows preserved α-type events. Thus, CCNA2-null cerebellar granule progenitor cells are capable of self-renewal of the EGL stem cell niche; this is concordant with prior findings of extensive apoptosis in CCNA2-null mice. Similar methodologies may provide another layer of depth to the interpretation of results from stereological studies.

Intrauterine Growth Restriction Affects Cerebellar Granule Cells in the Developing Guinea Pig Brain

“…Thus, we did not detect any major effect in proliferation; however, we acknowledge that markers of cell cycle dynamics other than those used here might have detected abnormalities. It is important, for example, that the appropriate type of cell division occurs at different stages of EGL development: predominantly symmetric division initially for surface area expansion and then asymmetric division during the growth phase [35]. With this caveat and taking our findings together across the 2 ages studied, we posit that there has been no major alteration in proliferation or cell cycle exit.…”

Surface topography during neural stem cell differentiation regulates cell migration and cell morphology

“…Timed‐pregnant CD‐1 females (Charles River, Burlington, MA) were sacrificed by CO 2 asphyxiation according to Institutional Animal Care and Use Committee (IACUC) guidelines. Fixation was performed as described previously (Chang et al, ; Otero et al, ). Briefly, embryos were dissected out and the brains were drop‐fixed in 4% paraformaldehyde overnight at 4 ºC.…”

“…The Journal of Comparative Neurology | Research in Systems Neuroscience (IACUC) guidelines. Fixation was performed as described previously (Chang et al, 2015;Otero et al, 2014). Briefly, embryos were dissected out and the brains were drop-fixed in 4% paraformaldehyde overnight at 4 C. The next day, the brains were transferred to a solution of 30% sucrose in phosphate-buffered saline (PBS) and incubated at 4 C with gentle agitation until they sank to the bottom of the tube (16-24 hours).…”

The influence of neurotransplantation with different allogenic tissues on the course of the spasticity and chronic pain syndrome after experimental spinal cord injury

“…• фетальний мозочок (перинатальний період розвитку) -містить значну кількість прекурсорів глутаматергічних нейронів [45,46], дозріваючі ГАМК*-ергічні клітини Пуркіньє [47] та численні онтогене-тичні регулятори -ефрини, семафорини, нетрини, кадгерини, представники сімейств FGF (fibroblast growth factor), Wnt ("wingless-like" intermediate) та BMP (bone morphogenetіc proteіn), білки Shh (sonіc hedgehog), PDGF (platelet-derived growth factor) та VEGF (vascular endothelial growth factor) [48][49][50][51];…”

“…На відміну від прекурсорів ГАМК-ергічних нейронів нюхової цибулини, попередники глутаматергічних нейронів кори мозочка в інтактних умовах мігрують на вкрай обмежену відстань (між шарами незрілої кори мозочка), причому за сприятливого тканинного ото-чення, наповненого достатньою кількістю необхідних репелентів чи атракторів [45,46]. Якщо тканина зрі-лого СМ певною мірою може нагадувати астроцитарні тунелі рострального міграторного потоку, подібність її з тканиною незрілого мозочка в усіх відношеннях за очевидних причин мінімальна.…”