Suzuki M, Raisman G
Norman and Sadie Lee Research Centre, Laboratory of Neurobiology, National Institute for Medical Research, London, United Kingdom.
Glia. 1994 Dec;12(4):294-308. doi: 10.1002/glia.440120406.
The development of the rat fimbria over the first postnatal month is associated with an approximate doubling of the tract diameter, a large increase in the number of glial cells, and the transformation of the prenatal radial glial skeleton into the adult interfascicular glial rows of solitary astrocytes and contiguous myelinating oligodendrocytes. The ventricular zone is reduced from a heterogeneous germinal layer of three or more cells thick at birth to the mature adult unicellular ependyma of homogeneous pale, mitotically inactive cells by the end of the second postnatal week. Mitoses are present throughout the body of the tract at all times, and persist, at reduced levels, in the adult. At birth the interior of the fimbria has only few scattered glial cell nuclei, largely solitary, or at most in longitudinal pairs. Over the first two postnatal weeks, the numbers and density of the interfascicular glia increase continuously. The scattered cells and cell clusters become progressively transformed into longer unicellular rows, which are aligned along the longitudinal axis of the tract, and which finally coalesce to form the continuous regular astrocyte/oligodendrocyte units that make up the interfascicular glial rows of the adult fimbrial glial skeleton. The increased cell packing density of the developing fimbrial glia is associated with a substantial decrease in nuclear and cytoplasmic size. From the end of the second postnatal week, the characteristic, large pale solitary astrocytes, and the smaller, more numerous, densely stained, closely packed oligodendrocytes are recognisable. Immunostaining for glial fibrillary acidic protein shows that immediately after birth the characteristic embryonic pattern of regular parallel radial glial processes starts to be modified by the progressive accumulation of longitudinal astrocytic processes, so the prenatal radial glial framework is rapidly transformed into the adult type of rectilinear array of radial and longitudinal processes. The development of the oligodendrocytes is shown clearly by immunostaining for myelin basic protein in enlarged, cytoplasm-rich, symmetrically placed cell pairs first seen at around P7. At P8-P10, there is a characteristic pattern of simultaneous multifocal maturation in which a single oligodendrocyte in each cluster develops a full complement of parallel, rather varicose myelinating processes. By P14 myelination is becoming confluent, oligodendrocytes are smaller, darker, with little cytoplasm, and individual myelinating processes cannot be discerned. Even at the end of the first postnatal month there are still many immature glia of indeterminate morphology. Myelination tends at first to be concentrated in the region adjacent to the hippocampus, and only reaches completion by the end of the second month.(ABSTRACT TRUNCATED AT 400 WORDS)
出生后第一个月大鼠海马伞的发育与束直径大约翻倍、胶质细胞数量大幅增加以及产前放射状胶质骨架转变为成人间质胶质细胞行（由单个星形胶质细胞和相邻的有髓少突胶质细胞组成）有关。脑室区从出生时三层或更多细胞厚的异质生发层，在出生后第二周结束时减少为成熟成人的单细胞室管膜，其由均匀浅色、有丝分裂不活跃的细胞组成。有丝分裂始终存在于束的整个主体中，并在成体中以较低水平持续存在。出生时，海马伞内部只有少数散在的胶质细胞核，大多为单个，或最多呈纵向成对。在出生后的前两周，束间胶质细胞的数量和密度持续增加。散在的细胞和细胞簇逐渐转变为更长的单细胞行，这些细胞行沿束的纵轴排列，最终合并形成构成成年海马伞胶质骨架束间胶质细胞行的连续规则星形胶质细胞/少突胶质细胞单元。发育中的海马伞胶质细胞的细胞堆积密度增加与细胞核和细胞质大小的显著减小有关。从出生后第二周结束开始，特征性的、大的浅色单个星形胶质细胞以及较小的、数量更多的、染色深且紧密排列的少突胶质细胞变得可识别。胶质纤维酸性蛋白的免疫染色显示，出生后立即，规则平行的放射状胶质细胞突起的特征性胚胎模式开始被纵向星形胶质细胞突起的逐渐积累所改变，因此产前放射状胶质框架迅速转变为成体类型的径向和纵向突起的直线排列。通过对髓鞘碱性蛋白的免疫染色可以清楚地看到少突胶质细胞的发育，在大约出生后7天首次在扩大的、富含细胞质的、对称放置的细胞对中看到。在出生后8 - 10天，有一种特征性的同时多灶成熟模式，其中每个簇中的单个少突胶质细胞发育出一整套平行的、相当曲张的有髓突起。到出生后14天，髓鞘形成开始融合，少突胶质细胞更小、颜色更深、细胞质很少，单个有髓突起无法分辨。即使在出生后第一个月末，仍有许多形态不确定的未成熟胶质细胞。髓鞘形成最初倾向于集中在海马附近区域，直到第二个月末才完成。（摘要截于400字）
