박쥐 망막의 조직화학적 분석 = Histochemical analysis of the Bat retina

다국어 초록 (Multilingual Abstract)

Many people think that bats are blind and it has been known that bats use acoustic orientations more than visual abilities to catch a prey and monitor their surroundings. Nevertheless, bats clearly have eyes. And so, these studies are intended to help to provide fundamental knowledge for the better understanding of the unique behavioral aspects of bat flight maneuverability by investigating and analyzing various neurons of outer nuclear layer, inner nuclear layer and ganglion cell layer of bat (the greater horseshoe bat, Rhinolophus ferrumequinum) for the first time.
At first, the quantitative analysis of cone and rod photoreceptors was made. The average cone density was 9,535 cells/mm2, giving the average number of cones of 33,538 cells per retina. The average rod density was 368,891 cells/mm2, giving the average number of rods of 1,303,517 cells. On average, rods were 97.49%, and cones were 2.51% of all the photoreceptors. Rod: cone ratios ranged from 33.85:1 centrally to 42.26:1 peripherally, with a mean ratio of 38.96:1. The average regularity index of the cone mosaic in bat retina was 3.04. The present results confirm that the greater horseshoe bat retina to be strongly rod-dominated.
Second, the investigation of parvalbumin-immunoreactive amacrine cells of inner nuclear layer in bat retina through immunocytochemistry, quantitative analysis, and confocal microscopy was made in detail. For the first time in a bat (the greater horseshoe bat, Rhinolophus ferrumequinum), it was identified that parvalbumin immunoreactivity is present in ganglion cell and inner nuclear layers. The regular distribution of parvalbumin-immunoreactive neurons, the inner marginal location of their cell bodies in the inner nuclear layer, and the distinctive bilaminar morphologies of their dendritic arbors in the inner plexiform layer suggested that these parvalbumin-immunoreactive cells were AⅡ amacrine cells. The average number of parvalbumin-immunoreactive amacrine cells was 11,033 cells per retina (n=3), and the mean density was 3,208 cells/mm2. The average regularity index of the parvalbumin-immunoreactive cell mosaic was 3.31. These results indicate that parvalbumin antibodies can be used to label AⅡ amacrine cells selectively in bats.
Finally, in this study, the parvalbumin-immunoreactive neurons in the ganglion cell layer of the retina of a bat, Rhinolophus ferrumequinum, and the distribution pattern of the labeled neurons were identified. Parvalbumin immunoreactivity was found in numerous cell bodies in the ganglion cell layer. Quantitative analysis showed that these cells had medium to large-sized somas. The soma diameter of the parvalbumin-immunoreactive cells in the ganglion cell layer ranged from 12.35 to 19.12 μm (n=166). As the fibers in the nerve fiber layer were also stained, the majority of parvalbumin-immunoreactive cells in the ganglion cell layer must be medium to large-sized retinal ganglion cells. The mean nearest neighbor distance of the parvalbumin-immunoreactive cells in the ganglion cell layer of the bat retina ranged from 59.57 to 62.45μm and the average regularity index was 2.95 ± 0.3 (n=4). The present results demonstrate that parvalbumin is expressed in medium to large-sized retinal ganglion cells in bat retina, and they have a well-organized distributional pattern with regular mosaics.
From the above studies, the rod-dominated retina with the existence of AII amacrine cells suggests that the greater horseshoe bat retina may have functional scotopic property of vision. Besides, the existence of cone cells suggests that the bat retina may have functional photopic property of vision, too.
Also, as AII cells are critically involved in both rod- and cone-driven signals by sending a vertical flow of information within the On- and Off- layers, the existence of AII amacrine cells suggests that bat retina has versatile synaptic connectivity and diverse functional physiology for vision.
And, retinal ganglion cells collect visual information in the eyes and finally send it to the brain for visual perception. Studies on the expression and cellular distribution of neurochemical substances in retinal ganglion cells are the basic information to understand a specific function of retinal ganglion cells. And so the immunocytochemical evidence of retinal ganglion cells expressing a specific protein in a microbat retina must be important.
Through these studies of bat retina, we are sure that microchiroptera not only rely on echolocation but also have functional eyes to help flight maneuverability and that these data are applicable to a better understanding of the unsolved issue of a bat vision.

목차 (Table of Contents)

• Ⅰ. 서론 = 1
• Ⅱ. 재료 및 방법 = 7
• 1.재료 및 조직준비 = 7
• 2.광수용체세포 staining = 8
• 3.면역세포화학적 조사 = 9
• 1) 내핵층-AⅡ 무축삭세포 = 9
• 2) 신경절세포층-신경절세포 = 10
• 4.정량 분석 = 12
• 1) 외핵층 = 12
• 2) 내핵층 = 13
• 3) 신경절세포층 = 14
• Ⅲ. 결과 및 고찰 = 15
• 1. 외핵층-광수용체세포 = 15
• 2. 내핵층-AⅡ 무축삭세포 = 25
• 3. 신경절세포층-신경절세포 = 34
• Ⅳ. 종합 고찰 = 44
• Ⅴ. 요약 = 58
• Ⅵ. 참고 문헌 = 62
• 영문 요약 = 83