Limits...
Morphological and Phagocytic Profile of Microglia in the Developing Rat Cerebellum(1,2,3).

Perez-Pouchoulen M, VanRyzin JW, McCarthy MM - eNeuro (2015)

Bottom Line: We found that microglial morphology changed from amoeboid to ramified during the first 3 postnatal weeks in a region specific manner.At P17 males showed an approximately twofold increase in microglia with thin processes compared with females.Our findings indicate a continuous process of microglial maturation and a nonuniform distribution of microglia in the cerebellar cortex that implicates microglia as an important cellular component of the developing cerebellum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, University of Maryland School of Medicine , Baltimore, Maryland 21201.

ABSTRACT
Microglia are being increasingly recognized as playing important roles in neurodevelopment. The cerebellum matures postnatally, undergoing major growth, but the role of microglia in the developing cerebellum is not well understood. Using the laboratory rat we quantified and morphologically categorized microglia throughout the vermis and across development using a design-based unbiased stereology method. We found that microglial morphology changed from amoeboid to ramified during the first 3 postnatal weeks in a region specific manner. These morphological changes were accompanied by the sudden appearance of phagocytic cups during the third postnatal week from P17 to P19, with an approximately fourfold increase compared with the first week, followed by a prompt decline at the end of the third week. The microglial phagocytic cups were significantly higher in the granular layer (∼69%) than in the molecular layer (ML; ∼31%) during a 3 d window, and present on ∼67% of microglia with thick processes and ∼33% of microglia with thin processes. Similar proportions of phagocytic cups associated to microglia with either thick or thin processes were found in the ML. We observed cell nuclei fragmentation and cleaved caspase-3 expression within some microglial phagocytic cups, presumably from dying granule neurons. At P17 males showed an approximately twofold increase in microglia with thin processes compared with females. Our findings indicate a continuous process of microglial maturation and a nonuniform distribution of microglia in the cerebellar cortex that implicates microglia as an important cellular component of the developing cerebellum.

No MeSH data available.


Related in: MedlinePlus

Identification of pyknotic bodies by Nissl staining in the postnatal developing cerebellum. A, The density of pyknotic bodies (red arrows) decreased only in the GL after the first postnatal week at P14, P17 and P21 (***p < 0.000), but not at P7 (p = 0.302), compared with P5. No changes in the density of pyknotic bodies were detected in the ML across the developmental time points analyzed when compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375). The GL exhibited more pyknotic bodies than the ML only during the first postnatal week at P5 (#p < 0.000) and P7 (^p < 0.000). Scale bar, 25 µm. Data are expressed as mean ± SEM (*n = 6, 3 males + 3 females; ^n = 4, 2 males + 2 females: *P5, ^P7, *P14, *P17, and *P21). B, P7 cerebellar sagittal section stained with cresyl violet showing pyknotic bodies pointed out by red arrows. Pk, Purkinje layer; EGL, external granular layer. C, Confocal colocalization of a pyknotic body (fragmented nucleus in yellow) and a phagocytic cup (red) in the cerebellar cortex at P17. Scale bars, 15 µm. D, 3D confocal image depicting a colocalization of a microglial phagocytic cup (red) and a cleaved caspase-3-positive cell (green) at the tip of a microglia process (white arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4596010&req=5

Figure 6: Identification of pyknotic bodies by Nissl staining in the postnatal developing cerebellum. A, The density of pyknotic bodies (red arrows) decreased only in the GL after the first postnatal week at P14, P17 and P21 (***p < 0.000), but not at P7 (p = 0.302), compared with P5. No changes in the density of pyknotic bodies were detected in the ML across the developmental time points analyzed when compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375). The GL exhibited more pyknotic bodies than the ML only during the first postnatal week at P5 (#p < 0.000) and P7 (^p < 0.000). Scale bar, 25 µm. Data are expressed as mean ± SEM (*n = 6, 3 males + 3 females; ^n = 4, 2 males + 2 females: *P5, ^P7, *P14, *P17, and *P21). B, P7 cerebellar sagittal section stained with cresyl violet showing pyknotic bodies pointed out by red arrows. Pk, Purkinje layer; EGL, external granular layer. C, Confocal colocalization of a pyknotic body (fragmented nucleus in yellow) and a phagocytic cup (red) in the cerebellar cortex at P17. Scale bars, 15 µm. D, 3D confocal image depicting a colocalization of a microglial phagocytic cup (red) and a cleaved caspase-3-positive cell (green) at the tip of a microglia process (white arrow).

Mentions: We quantified the density of pyknotic bodies in the cerebellar cortex (Fig. 6B) at different postnatal time points to establish a pattern of cell death and to see whether it correlated with the pattern of increased phagocytosis at P17. A significant interaction between age X cerebellar layer for pyknotic bodies was detected (p < 0.000)p. Pyknotic bodies density decreased in the GL at P14 (p < 0.000), P17 (p < 0.000) and P21 (p < 0.000) compared with P7, but not at P5 (p = 0.751; Fig. 6A). No changes in the density of pyknotic bodies were detected in the ML in any of the developmental time points analyzed compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375; Fig. 6). Moreover, there were more pyknotic bodies in the GL than the ML at P5 (p < 0.000) and P7 (p < 0.000), but not at later ages (P14, p = 0.134; P17, p = 0.922; P21, p = 0.194; Fig. 6A). These data indicate there is not a clear relationship between the appearance of both phagocytic cups and pyknotic bodies in the developing cerebellum.


Morphological and Phagocytic Profile of Microglia in the Developing Rat Cerebellum(1,2,3).

Perez-Pouchoulen M, VanRyzin JW, McCarthy MM - eNeuro (2015)

Identification of pyknotic bodies by Nissl staining in the postnatal developing cerebellum. A, The density of pyknotic bodies (red arrows) decreased only in the GL after the first postnatal week at P14, P17 and P21 (***p < 0.000), but not at P7 (p = 0.302), compared with P5. No changes in the density of pyknotic bodies were detected in the ML across the developmental time points analyzed when compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375). The GL exhibited more pyknotic bodies than the ML only during the first postnatal week at P5 (#p < 0.000) and P7 (^p < 0.000). Scale bar, 25 µm. Data are expressed as mean ± SEM (*n = 6, 3 males + 3 females; ^n = 4, 2 males + 2 females: *P5, ^P7, *P14, *P17, and *P21). B, P7 cerebellar sagittal section stained with cresyl violet showing pyknotic bodies pointed out by red arrows. Pk, Purkinje layer; EGL, external granular layer. C, Confocal colocalization of a pyknotic body (fragmented nucleus in yellow) and a phagocytic cup (red) in the cerebellar cortex at P17. Scale bars, 15 µm. D, 3D confocal image depicting a colocalization of a microglial phagocytic cup (red) and a cleaved caspase-3-positive cell (green) at the tip of a microglia process (white arrow).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596010&req=5

Figure 6: Identification of pyknotic bodies by Nissl staining in the postnatal developing cerebellum. A, The density of pyknotic bodies (red arrows) decreased only in the GL after the first postnatal week at P14, P17 and P21 (***p < 0.000), but not at P7 (p = 0.302), compared with P5. No changes in the density of pyknotic bodies were detected in the ML across the developmental time points analyzed when compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375). The GL exhibited more pyknotic bodies than the ML only during the first postnatal week at P5 (#p < 0.000) and P7 (^p < 0.000). Scale bar, 25 µm. Data are expressed as mean ± SEM (*n = 6, 3 males + 3 females; ^n = 4, 2 males + 2 females: *P5, ^P7, *P14, *P17, and *P21). B, P7 cerebellar sagittal section stained with cresyl violet showing pyknotic bodies pointed out by red arrows. Pk, Purkinje layer; EGL, external granular layer. C, Confocal colocalization of a pyknotic body (fragmented nucleus in yellow) and a phagocytic cup (red) in the cerebellar cortex at P17. Scale bars, 15 µm. D, 3D confocal image depicting a colocalization of a microglial phagocytic cup (red) and a cleaved caspase-3-positive cell (green) at the tip of a microglia process (white arrow).
Mentions: We quantified the density of pyknotic bodies in the cerebellar cortex (Fig. 6B) at different postnatal time points to establish a pattern of cell death and to see whether it correlated with the pattern of increased phagocytosis at P17. A significant interaction between age X cerebellar layer for pyknotic bodies was detected (p < 0.000)p. Pyknotic bodies density decreased in the GL at P14 (p < 0.000), P17 (p < 0.000) and P21 (p < 0.000) compared with P7, but not at P5 (p = 0.751; Fig. 6A). No changes in the density of pyknotic bodies were detected in the ML in any of the developmental time points analyzed compared with P7 (P5, p = 0.199; P14, p = 0.688; P17, p = 0.487; P21, p = 0.375; Fig. 6). Moreover, there were more pyknotic bodies in the GL than the ML at P5 (p < 0.000) and P7 (p < 0.000), but not at later ages (P14, p = 0.134; P17, p = 0.922; P21, p = 0.194; Fig. 6A). These data indicate there is not a clear relationship between the appearance of both phagocytic cups and pyknotic bodies in the developing cerebellum.

Bottom Line: We found that microglial morphology changed from amoeboid to ramified during the first 3 postnatal weeks in a region specific manner.At P17 males showed an approximately twofold increase in microglia with thin processes compared with females.Our findings indicate a continuous process of microglial maturation and a nonuniform distribution of microglia in the cerebellar cortex that implicates microglia as an important cellular component of the developing cerebellum.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology, University of Maryland School of Medicine , Baltimore, Maryland 21201.

ABSTRACT
Microglia are being increasingly recognized as playing important roles in neurodevelopment. The cerebellum matures postnatally, undergoing major growth, but the role of microglia in the developing cerebellum is not well understood. Using the laboratory rat we quantified and morphologically categorized microglia throughout the vermis and across development using a design-based unbiased stereology method. We found that microglial morphology changed from amoeboid to ramified during the first 3 postnatal weeks in a region specific manner. These morphological changes were accompanied by the sudden appearance of phagocytic cups during the third postnatal week from P17 to P19, with an approximately fourfold increase compared with the first week, followed by a prompt decline at the end of the third week. The microglial phagocytic cups were significantly higher in the granular layer (∼69%) than in the molecular layer (ML; ∼31%) during a 3 d window, and present on ∼67% of microglia with thick processes and ∼33% of microglia with thin processes. Similar proportions of phagocytic cups associated to microglia with either thick or thin processes were found in the ML. We observed cell nuclei fragmentation and cleaved caspase-3 expression within some microglial phagocytic cups, presumably from dying granule neurons. At P17 males showed an approximately twofold increase in microglia with thin processes compared with females. Our findings indicate a continuous process of microglial maturation and a nonuniform distribution of microglia in the cerebellar cortex that implicates microglia as an important cellular component of the developing cerebellum.

No MeSH data available.


Related in: MedlinePlus