Jeong Mi-Jin, Kim Hang-Gu, Jeon Chang-Jin
Department of Biology, School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, College of Natural Sciences, and Brain Science and Engineering Institute, Kyungpook National University, Daegu, South Korea.
PLoS One. 2018 Jan 5;13(1):e0190435. doi: 10.1371/journal.pone.0190435. eCollection 2018.
Intrinsically photosensitive retinal ganglion cells (ipRGCs) respond to light and play roles in non-image forming vision, such as circadian rhythms, pupil responses, and sleep regulation, or image forming vision, such as processing visual information and directing eye movements in response to visual clues. The purpose of the present study was to identify the distribution, types, and proportion of melanopsin-immunoreactive (IR) cells in the retina of a nocturnal animal, i.e., the microbat (Rhinolophus ferrumequinum). Three types of melanopsin-IR cells were observed in the present study. The M1 type had dendritic arbors that extended into the OFF sublayer of the inner plexiform layer (IPL). M1 soma locations were identified either in the ganglion cell layer (GCL, M1c; 21.00%) or in the inner nuclear layer (INL, M1d; 5.15%). The M2 type had monostratified dendrites in the ON sublayer of the IPL and their cell bodies lay in the GCL (M2; 5.79%). The M3 type was bistratified cells with dendrites in both the ON and OFF sublayers of the IPL. M3 soma locations were either in the GCL (M3c; 26.66%) or INL (M3d; 4.69%). Additionally, some M3c cells had curved dendrites leading up towards the OFF sublayer of the IPL and down to the ON sublayer of the IPL (M3c-crv; 7.67%). Melanopsin-IR cells displayed a medium soma size and medium dendritic field diameters. There were 2-5 primary dendrites and sparsely branched dendrites with varicosities. The total number of the neurons in the GCL was 12,254.17 ± 660.39 and that of the optic nerve axons was 5,179.04 ± 208.00 in the R. ferrumequinum retina. The total number of melanopsin-IR cells was 819.74 ± 52.03. The ipRGCs constituted approximately 15.83% of the total RGC population. This study demonstrated that the nocturnal microbat, R. ferrumequinum, has a much higher density of melanopsin-IR cells than documented in diurnal animals.
内在光敏性视网膜神经节细胞（ipRGCs）对光作出反应，并在非成像视觉（如昼夜节律、瞳孔反应和睡眠调节）或成像视觉（如处理视觉信息以及根据视觉线索引导眼球运动）中发挥作用。本研究的目的是确定夜行性动物——菊头蝠（Rhinolophus ferrumequinum）视网膜中黑素视蛋白免疫反应性（IR）细胞的分布、类型和比例。本研究观察到三种类型的黑素视蛋白IR细胞。M1型细胞的树突分支延伸至内网层（IPL）的OFF亚层。M1型细胞的胞体位于神经节细胞层（GCL，M1c；21.00%）或内核层（INL，M1d；5.15%）。M2型细胞在IPL的ON亚层有单分层树突，其胞体位于GCL（M2；5.79%）。M3型细胞为双分层细胞，树突分布于IPL的ON亚层和OFF亚层。M3型细胞的胞体位于GCL（M3c；26.66%）或INL（M3d；4.69%）。此外，一些M3c细胞有弯曲的树突，向上延伸至IPL的OFF亚层，向下延伸至IPL的ON亚层（M3c-crv；7.67%）。黑素视蛋白IR细胞的胞体大小和树突野直径中等。有2 - 5条初级树突，树突分支稀疏且有膨体。菊头蝠视网膜中GCL的神经元总数为12,254.17 ± 660.39，视神经轴突总数为5,179.04 ± 208.00。黑素视蛋白IR细胞总数为819.74 ± 52.03。ipRGCs约占视网膜神经节细胞总数的15.83%。本研究表明，夜行性菊头蝠视网膜中黑素视蛋白IR细胞的密度比昼行性动物中记录的密度高得多。
