CYTOGENESIS IN THE MONKEY RETINA
CYTOGENESIS IN THE MONKEY RETINA
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DOI：
10.1002/cne.903090107
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发表时间：
1991-07-01
影响因子：
2.5
通讯作者：
RAKIC, P
中科院分区：
文献类型：
--
作者：
LAVAIL, MM;RAPAPORT, DH;RAKIC, P
通过绘制 2 至 6 个月大的动物放射自显影图中重度放射性标记的细胞核数量来研究恒河猴 (Macaca mulatta) 视网膜中细胞起源的时间，每个动物在单个胚胎 (E) 或出生后 (P) 日均暴露于 H-3-胸苷 (H-3-TdR) 脉冲。 猴子视网膜中的细胞在 E27 之后开始生成，大约 96% 的细胞是由 E120 生成的。 剩余的细胞是在产前最后（大约 45 天）和出生后最初几周内产生的。 细胞发生在中央凹附近开始，并向周边进行。 E56 在中心凹和中心凹周围区域的细胞分裂很大程度上停止。尽管存在广泛的重叠，但观察到了特定类别的细胞诞生顺序。 首先诞生的神经节细胞和水平细胞的细胞发生时期基本一致，峰值在 E38 和 E43 之间，终止于 E70 左右。 第一个标记的视锥细胞在 E33 时很明显，它们的最高密度在 E43 和 E56 之间达到，在 E70 时逐渐减小到较低值，尽管晚至 E110 在最外围生成了一些视锥细胞。 无长突细胞是细胞诞生序列中的下一个细胞，在 E43 开始发生，在 E56 和 E85 之间达到峰值，并在 E110 停止。 双极细胞的诞生与无长突同时开始，但似乎在时间上与无长突细胞分离，因为它们的产生在 E56 和 E102 之间达到顶峰，并持续到出生当天之后。 Muller细胞和视杆光感受器在E45开始生成，达到峰值，并与双极细胞同时密度下降，但在出生当天继续以低密度生成。 因此，双极细胞、穆勒细胞和杆状细胞具有相似的时间或起源。 细胞诞生的最大时间间隔是在视锥细胞和无长突细胞之间，因此细胞生成表现出两个相对不同的阶段：第一阶段产生神经节细胞、水平细胞和视锥细胞，第二阶段产生无长突细胞、双极细胞、杆状细胞和米勒细胞。 此外，第一相细胞的生成速度比第二相细胞快，并且两相之间标记细胞的扩散地形存在差异。每个细胞类别在发生过程中都显示出中央到外周的梯度，尽管不同类别之间梯度的时空特征不同。 重度标记的神经节细胞、水平细胞和视锥细胞（第 1 阶段）在视网膜边缘附近比无长突细胞、双极细胞、Muller 细胞和视杆细胞（第 2 阶段）更早被发现。 因此，第 1 相细胞的发生通常发生在更广泛的视网膜区域，延伸至视网膜边缘，而第 2 相细胞发生在细胞在边缘附近开始发生时集中停止。 细胞分裂最初停止的部位比细胞发生开始时的部位变化更大，尽管对于所有细胞类别来说，它大致以中央凹为中心。
Time of cell origin in the retina of the rhesus monkey (Macaca mulatta) was studied by plotting the number of heavily radiolabeled nuclei in autoradiograms prepared from 2- to 6-month-old animals, each of which was exposed to a pulse of H-3-thymidine (H-3-TdR) on a single embryonic (E) or postnatal (P) day. Cell birth in the monkey retina begins just after E27, and approximately 96% of cells are generated by E120. The remaining cells are produced during the last (approximately 45) prenatal days and into the first several weeks after birth. Cell genesis begins near the fovea, and proceeds towards the periphery. Cell division largely ceases in the foveal and perifoveal regions by E56.Despite extensive overlap, a class-specific sequence of cell birth was observed. Ganglion and horizontal cells, which are born first, have largely congruent periods of cell genesis with the peak between E38 and E43, and termination around E70. The first labeled cones were apparent by E33, and their highest density was achieved between E43 and E56, tapering to low values at E70, although some cones are generated in the far periphery as late as E110. Amacrine cells are next in the cell birth sequence and begin genesis at E43, reach a peak production between E56 and E85, and cease by E110. Bipolar cell birth begins at the same time as amacrines, but appears to be separate from them temporally since their production reaches a peak between E56 and E102, and persists beyond the day of birth. Muller cells and rod photoreceptors, which begin to be generated at E45, achieve a peak, and decrease in density at the same time as bipolar cells, but continue genesis at low density on the day of birth. Thus, bipolar, Muller, and rod cells have a similar time or origin. The maximal temporal separation of cell birth is between cones and amacrine cells so that cell generation exhibits two relatively distinct phases: the first phase gives rise to ganglion, horizontal, and cone cells, and the second phase to amacrine, bipolar, rod, and Muller cells. In addition, cells of the first phase are generated faster than the second phase cells, and there are differences in the topography of spread of labeled cells between the two phases.Each cell class displays a central-to-peripheral gradient in genesis, although the spatiotemporal characteristics of the gradients differ between the classes. Heavily labeled ganglion cells, horizontal cells, and cone photoreceptors (phase 1) are found near the retinal margin much sooner than amacrine, bipolar, Muller, and rod photoreceptor cells (phase 2). As a consequence, genesis of phase 1 cells generally occurs over a more extensive retinal area, extending to the retinal margin, while phase 2 cell genesis ceases centrally by the time cell birth begins near the margin. The site of initial cessation of cell division is more variable than it is for the beginning of cytogenesis, although for all cell classes it is roughly centered on the fovea.