Changes in Retinal Structure and Function in Mice Exposed to Flickering Blue Light: Electroretinographic and Optical Coherence Tomographic Analyses

The harmful effects of blue light on the retina and health issues attributed to flickering light have been researched extensively. However, reports on the effects of flickering blue light at a frequency in the visible range on the retina are limited. This study aimed to non-invasively investigate the structural and functional changes in mice retinas following exposure to flickering blue light. BALB/c mice were subjected to non-flickering and flickering blue light, and changes in the retinal function and structure were assessed using electroretinography (ERG) and spectral-domain optical coherence tomography (SD-OCT), respectively. Retinal damage progression was monitored on days 3, 7, 14, and 42 following light exposure. Significant reductions in scotopic and photopic ERG responses were observed on day 3 (p0.05). A similar trend lasted by day 14. On day 42, however, the difference between the non-flickering and flickering groups was significant, which was corroborated by the normalized amplitudes at 0, 0.5, and 1 log cd s/ m 2 (p<0.05). Quantitative and qualitative SD-OCT assays revealed more severe and progressive retinal damage in the flickering group throughout the study. Flickering blue light causes more persistent and severe retinal damage than non-flickering blue light and may be a risk factor for retinal degeneration even at frequencies as low as 20 Hz.

A Brief Review of Anatomy Education in Korea, Encompassing Its Past, Present, and Future Direction

Anatomy is a foundational subject in medicine and serves as its language. Hippocrates highlighted its importance, while Herophilus pioneered human dissection, earning him the title of the founder of anatomy. Vesalius later established modern anatomy, which has since evolved historically. In Korea, formal anatomy education for medical training began with the introduction of Western medicine during the late Joseon Dynasty. Before and after the Japanese occupation, anatomy education was conducted in the German style, and after liberation, it was maintained and developed by a small number of domestic anatomists. Medicine in Korea has grown alongside the country’s rapid economic and social development. Today, 40 medical colleges produce world-class doctors to provide the best medical care service in the country. However, the societal demand for more doctors is growing in order to proactively address to challenges such as public healthcare issues, essential healthcare provision, regional medical service disparities, and an aging population.This study examines the history, current state, and challenges of anatomy education in Korea, emphasizing the availability of medical educators, support staff, and cadavers for gross anatomy instruction. While variations exist between Seoul and provincial medical colleges, each manages to deliver adequate education under challenging conditions. However, the rapid increase in medical student enrollment threatens to strain existing anatomy education resources, potentially compromising educational quality. To address these concerns, we propose strategies for training qualified gross anatomy educators, ensuring a sustainable cadaver supply, and enhancing infrastructure.

Therapeutic Efficacy of Bone Marrow Derived Mesenchymal Stem Cells in Ototoxic Sensorineural Hearing Loss / 대한이비인후과학회지

Background and Objectives@#Ototoxic sensorineural hearing loss causes permanent hearing loss in most cases. Recently there have been many reports describing cell base therapy with stem cells that has some effect on hearing recovery. We evaluated the efficacy of clinical grade, pre-made, human bone marrow derived mesenchymal stem cells (BM-MSCs) in ototoxic deaf animal model.Materials and Method BM-MSCs were cultured in a clinical grade laboratory. The animals were divided into 2 groups as follows: a saline injected control group and a stem cell injected group (MSC-group). Cultured MSCs were transplanted into the brachial vein of the deaf mice model. We recorded auditory brainstem response (ABR) and conducted immunohistochemistry at 1, 3, and 5 weeks. @*Results@#After the transplantation of MSC, a significant improvement in the hearing threshold of ABR was observed in the MSC transplanted group. Five weeks after transplantation of MSCs, hair cell regeneration was confirmed from the basal to the apex of the cochlea in fluorescent dyed image under the microscope compared to the control group. @*Conclusion@#BM-MSCs were effective in an acute ototoxic deaf animal model. These results show that stem cell transplantation mediate inner ear regeneration.

Tricyclic antidepressant amitriptyline inhibits 5-hydroxytryptamine 3 receptor currents in NCB-20 cells

Amitriptyline, a tricyclic antidepressant, is commonly used to treat depression and neuropathic pain, but its mechanism is still unclear. We tested the effect of amitriptyline on 5-hydroxytryptamine 3 (5-HT₃) receptor currents and studied its blocking mechanism because the clinical applications of amitriptyline overlapped with 5-HT₃ receptor therapeutic potentials. Using a whole-cell voltage clamp method, we recorded the currents of the 5-HT₃ receptor when 5-HT was applied alone or co-applied with amitriptyline in cultured NCB-20 neuroblastoma cells known to express 5-HT₃ receptors. To elucidate the mechanism of amitriptyline, we simulated the 5-HT₃ receptor currents using Berkeley Madonna® software and calculated the rate constants of the agonist binding and receptor transition steps. The 5-HT₃ receptor currents were inhibited by amitriptyline in a concentration-dependent, voltage-independent manner, and a competitive mode. Amitriptyline accelerated the desensitization of the 5-HT₃ receptor. When amitriptyline was applied before 5-HT treatment, the currents rose slowly until the end of 5-HT treatment. When amitriptyline was co-applied with 5-HT, currents rose and decayed rapidly. Peak current amplitudes were decreased in both applications. All macroscopic currents recorded in whole cell voltage clamping experiments were reproduced by simulation and the changes of rate constants by amitriptyline were correlated with macroscopic current recording data. These results suggest that amitriptyline blocks the 5-HT₃ receptor by close and open state blocking mechanisms, in a competitive manner. We could expand an understanding of pharmacological mechanisms of amitriptyline related to the modulation of a 5-HT₃ receptor, a potential target of neurologic and psychiatric diseases through this study.

The Transient Intermediate Plexiform Layer, a Plexiform Layer-like Structure Temporarily Existing in the Inner Nuclear Layer in Developing Rat Retina

The retina is a highly specialised part of the brain responsible for visual processing. It is well-laminated; three layers containing five different types of neurons are compartmentalised by two synaptic layers. Among the retinal layers, the inner nuclear layer (INL) is composed of horizontal, bipolar, and amacrine cell types. Bipolar cells form one sublayer in the distal half of the IPL, while amacrine cells form another sublayer in the proximal half, without any border-like structure. Here, we report that a plexiform layer-like structure exists temporarily in the border between the bipolar and amacrine sublayers in the INL in the rat retina during retinal development. This transient intermediate plexiform layer (TIPL) appeared at postnatal day (PD) 7 and then disappeared around PD 12. Most apoptotic cells in the INL were found near the TIPL. These results suggest that the TIPL may contribute to the formation of sublayers and the cell number limit in the INL.

Blue-on-Green Flash Induces Maximal Photopic Negative Response and Oscillatory Potential and Serves as a Diagnostic Marker for Glaucoma in Rat Retina

The purpose of this study was to investigate the application of various electroretinography (ERG) to the diagnosis of inner retinal dysfunction induced by mild intraocular pressure (IOP) elevation in a rat glaucoma model. For inner retinal function measurements, available photopic ERG protocols were applied under various light conditions including monochromatic combinations, which complement conventional scotopic ERG. Three episcleral veins in the right eyes of Sprague-Dawley rats were cauterized to induce an experimental model of glaucoma, leading to mild IOP elevation. ERG responses were measured before surgery and at 1, 2, 4, and 8 weeks after cauterization. We first confirmed that the amplitude reduction in the standard photopic b-wave was almost comparable to the amplitudes of scotopic a- and b-waves in glaucomatous eyes over time. We have implemented additional photopic ERG protocols under different stimulus conditions, which consisted of a longer duration and different monochromatic combinations. Such a change in the stimulations resulted in more pronounced differences in response between the two groups. Especially in normal animals, blue stimulation on a green background produced the largest b-wave and photopic negative response (PhNR) amplitudes and caused more pronounced oscillatory potential (OP) wavelets (individual components). In glaucomatous eyes, blue stimulation on a green background significantly reduced PhNR amplitudes and abolished the robust OP components. These results, by providing the usefulness of blue on green combination, suggest the applicable photopic ERG protocol that complements the conventional ERG methods of accessing the progression of glaucomatous damage in the rat retina.

Reexamination of Dopaminergic Amacrine Cells in the Rabbit Retina: Confocal Analysis with Double- and Triple-labeling Immunohistochemistry

Dopaminergic amacrine cells (DACs) are among the most well-characterized neurons in the mammalian retina, and their connections to AII amacrine cells have been described in detail. However, the stratification of DAC dendrites differs based on their location in the inner plexiform layer (IPL), raising the question of whether all AII lobules are modulated by dopamine release from DACs. The present study aimed to clarify the relationship between DACs and AII amacrine cells, and to further elucidate the role of dopamine at synapses with AII amacrine cell. In the rabbit retina, DAC dendrites were observed in strata 1, 3, and 5 of the IPL. In stratum 1, most DAC dendritic varicosities—the presumed sites of neurotransmitter release—made contact with the somata and lobular appendages of AII amacrine cells. However, most lobular appendages of AII amacrine cells localized within stratum 2 of the IPL exhibited little contact with DAC varicosities. In addition, double- or triple-labeling experiments revealed that DACs did not express the GABAergic neuronal markers anti-GABA, vesicular GABA transporter, or glutamic acid decarboxylase. These findings suggest that the lobular appendages of AII amacrine cells are involved in at least two different circuits. We speculate that the circuit associated with stratum 1 of the IPL is modulated by DACs, while that associated with stratum 2 is modulated by unknown amacrine cells expressing a different neuroactive substance. Our findings further indicate that DACs in the rabbit retina do not use GABA as a neurotransmitter, in contrast to those in other mammals.

The Size of the Rotator Cuff and the Positional Relationship of Bony Landmarks: An Anatomical Study / 체질인류학회지

For treatment of the rotator cuff, locating the structure and position of the rotator cuff is crucial. The aim of this study is to identify the size of each rotator cuff and the locational relationship with bony landmarks, and to provide superficial landmarks for locating the tendon from the surface. Fifty-two shoulders from 26 cadavers were dissected and measured in a supine position. The central point was set as the most protrusive point on the greater tubercle of the humerus. The measurement of angles was described ventral as positive (+) and dorsal as negative (-) placing the long axis of the humeral shaft at 0degrees. The range of the angle which each rotator cuff tendon is attached to the humerus head was: 53.8~103.3 degrees for the subscapularis, -17.1~25.7 degrees for the supraspinatus, -68.4~-1.9 degrees for the infraspinatus, and -117.1~-75.7 degrees for the teres minor. The vertical inferior point drawn from the anterior edge of the acromion to the humerus was 7.5+/-11.7 degrees from the central point. The average position of the point was the midpoint of insertion of the supraspinatus tendon. The lateral horizontal point drawn from the acromial angle to the humerus was -49.4+/-14.3 degrees away and located at an average of 30% inferior to the infraspinatus tendon. Also the lateral horizontal point drawn from the most protrusive point of the coracoid process to the humerus was 63.1+/-14.7 degrees away and located at an average of 20% superior to the subscapularis tendon. Lastly, the most protrusive point of the lesser tubercle of the humerus was located at a range of 80.8+/-11.1 degrees and an average of 60% superior to the insertion of the subscapularis tendon. For the measurements of the size of the rotator cuff, there was no statistical difference between the left and right. However, the four measurements - the proximal width of the teres minor tendon, the proximal and distal width, and the length of the subscapularis tendon - showed statistically significant difference between the sexes (P<0.05). Therefore, to identify the location of the tendon structures by palpation for shoulder treatment, using the lesser tubercle for the subscapularis, the anterior edge of the acromion for the supraspinatus, and the acromial angle for the infraspinatus as landmarks is regarded to be effective.

The Location of the Modiolus in Living Korean / 체질인류학회지

Modiolus is convergence of the facial muscles at the angle of the mouth, and its shape and size varying with individual, age, sex and ethnicity. In the previous study, the modiolus was usually located under the horizontal line at the mouth angle. In most medical schools, the cadavers are of later ages and their facial muscles have lost their elasticity as they got older. The purpose of this study is to identify the location of the modiolus in live young Korean and to compare it with that of Korean cadavers from the previous study. Participants were one hundred students of the catholic medical school with a mean age of 24 years. Experimenter palpated the modiolus of each student with thumb and index finger. The average young live Korean modiolus was located at 14.4 mm lateral to mouth angle and 1.6 mm below the horizontal line of the mouth angle. Commonly, it is located below the mouth angle in 124 sides (62%). There was difference between horizontal distance of female and of male, and vertical distance of right and of left. The location of the modiouls was symmetric in 67%. These results were consistent with the previous study using Korean cadavers. Therefore these results suggest that the location of the modiolus is below to the mouth angle in large number of Koreans.

Ribbon Synapses Formed at the Axon of the Calbindin-Immunoreactive ON Cone Bipolar Cell in OFF Sublamina of the Inner Plexiform Layer in the Rabbit Retina / 체질인류학회지

Some retinal neurons, including intrinsically photosensitive retinal ganglion cells have their dendrites stratified in sublamina a of the inner plexiform (IPL), the OFF sublayer, but paradoxically show light-driven ON electrophysiological responses. In order to understand the mechanism on this paradoxical response, by using immunoelectron microscopy with a specific antibody against calbindin, we examined the synaptic connections of the calbindin-immunoreactive ON cone bipolar cell of the rabbit retina, which is thought to make the ribbon synapse in sublamina a of the IPL. The ribbon synapses in sublamina a by calbindin-immunoreactive ON cone bipolar cells were mainly found at the border between the inner nuclear layer and the IPL. Interestingly, the output targets at these ribbon synapses turned out as monads, and multiple synaptic ribbons were engaged in each synapse. These findings were different from those at the conventional ribbon synapse formed by calbindin-immunoreactive ON cone bipolar axon terminals. Thus, these findings may be the characteristics of the calbindin-immunoreactive ON cone bipolar ribbon synapse in sublamina a and can be used to classify the synapse in the retinal circuit research.

Morphological and functional evaluation of an animal model for the retinal degeneration induced by N-methyl-N-nitrosourea / 대한해부학회지

The retinal degeneration (RD) is a general cause of blindness. To study its pathophysiology and evaluate the effects of new therapeutic agents before clinical trials, it is essential to establish reliable and stable animal models. This study evaluated a RD animal model in which blindness was induced by N-methyl-N-nitrosourea (MNU), a potent retinotoxin leading to apoptosis of photoreceptors. MNU was applied to the Sprague-Dawley rats by a single intraperitoneal injection in different doses (40, 50, and 60 mg/kg). The retinal functions were examined at 1 week after MNU injection by electroretinogram (ERG). Afterwards, each retina was examined by hematoxylin and eosin stain and immunohistochemistry with anti-glial fibrillary acidic protein antibody. Upon MNU injection of 40, 50 and 60 mg/kg, the ERG amplitude of a-waves showed significant reductions of 7, 26, and 44%, respectively, when compared to that of normal a-waves. The b-wave amplitudes were about 89, 65, and 58% of normal b-waves in the response to scotopic light stimulus. At 1 week, 2 weeks, and 4 weeks after MNU injection (50 mg/kg), all scotopic ERG components decreased progressively. In addition, degeneration of retinal neurons was observed in a time- and dose-dependent manner after MNU injection. Taken together, functional reduction following RD induced by MNU correlates with morphological changes. Thus, this RD rat model may be a useful model to study its pathophysiology and to evaluate the effects of new therapeutic agents before clinical trials.

Changes in transcript and protein levels of calbindin D28k, calretinin and parvalbumin, and numbers of neuronal populations expressing these proteins in an ischemia model of rat retina / 대한해부학회지

Excessive calcium is thought to be a critical step in various neurodegenerative processes including ischemia. Calbindin D28k (CB), calretinin (CR), and parvalbumin (PV), members of the EF-hand calcium-binding protein family, are thought to play a neuroprotective role in various pathologic conditions by serving as a buffer against excessive calcium. The expression of CB, PV and CR in the ischemic rat retina induced by increasing intraocular pressure was investigated at the transcript and protein levels, by means of the quantitative real-time reverse transcription-polymerase chain reaction, western blot and immunohistochemistry. The transcript and protein levels of CB, which is strongly expressed in the horizontal cells in both normal and affected retinas, were not changed significantly and the number of CB-expressing horizontal cells remained unchanged throughout the experimental period 8 weeks after ischemia/reperfusion injury. At both the transcript and protein levels, however, CR, which is strongly expressed in several types of amacrine, ganglion, and displaced amacrine cells in both normal and affected retinas, was decreased. CR-expressing ganglion cell number was particularly decreased in ischemic retinas. Similar to the CR, PV transcript and protein levels, and PV-expressing AII amacrine cell number were decreased. Interestingly, in ischemic retinas PV was transiently expressed in putative cone bipolar cell types possibly those that connect with AII amacrine cells via gap junctions. These results suggest that these three calcium binding proteins may play different neuroprotective roles in ischemic insult by their ability to buffer calcium in the rat retina.

Morphology and Distribution of Gap Junction in Horizontal Cells of the Rabbit Retina / 대한해부학회지

Horizontal cells (HCs) of the mammalian retina are interneurons that provide negative feedback to photoreceptors in the outer plexiform layer (OPL) where the first synapse occurs and contribute to the center surround antagonism that underlies the receptive field properties of many retinal neurons. These functions of HCs are thought to be attributed to their coupled network via gap junctions. Two kinds of connexin (Cx) proteins, Cx50 and 57 are known to form gap junctions of HCs. However, little is known about precise localization of gap junctions within HCs. Thus, this study was designed to determine the localization of HC gap junctions at subcellular level. In vertical ultrathin sections of the rabbit retina, gap junctions composed of Cx50 and 57 were identified in the OPL by the electron-dense reaction products. Each Cx50 and 57 gap junction on putative HC processes showed its own distinct features. Cx50 gap junction was bigger in size and localized more proximally than Cx57. In addition, Cx57 gap junctions had distinct shape. That is, about a half of them appeared to be invaginated or endocytosed in shape. The differences in shape, size and subcellular localization between Cx50 and 57 gap junctions may provide the insights into the function of different types of horizontal cell.

Changes in Osteopontin Expression in the Rat Lumbar Spinal Cord Following the Avulsion of Lumbar Nerve Roots / 대한해부학회지

This study investigated the expression of osteopontin (OPN) in rat lumbar spinal cords after lumbar nerve root avulsion, using in situ hybridization histochemistry, immunocytochemistry and western blot analysis. Cells expressing OPN were motoneurons and interneurons in the ventral horn, but no signals were observed in neurons in the dorsal horn of the normal lumbar spinal cord. From day 1 after avulsion injury, OPN mRNA-labeled neurons increased in the ventral horn and the intermediate zone. By day 3, relatively strong OPN mRNA signals were found throughout the gray matter of the injured side of the spinal cord with OPN mRNA-labeled cells scattered in the superficial dorsal horn. By day 7, the labeling patterns for OPN mRNA were similar to those on day 3, but the numbers of OPN mRNA-labeled cells in the ventral horn and the intermediate zone peaked. At this point, these labeled cells were also more densely packed and the intensity of signals was stronger. Interestingly, these labeled cells were neurons, but not glial cells such as astrocytes or microglia. This OPN mRNA-labeled cell profile in the dorsal horn had nearly disappeared by day 14 after avulsion injury, and the labeling pattern became similar to that on day 1. By day 28, after avulsion injury, the numbers of OPN mRNA-labeled cells decreased further below control values. These results suggest that increased expression of OPN in the rat lumbar spinal cord after avulsion injury might play an important role in the pathogenesis of damaged neurons.

Morphology and Synaptic Pattern of Calretinin-immunoreactive Neurons in the Superficial Dorsal Horn of the Rat Spinal Cord / 대한해부학회지

The distribution and the synaptic relationships of calretinin-immunoreactive neurons were studied in the superficial dorsal horn of the rat spinal cord. Calretinin-immunoreactive neurons and fibers were found in all laminae of spinal cord. The densest staining of both cell bodies and fibers occurred in the superficial laminae. In lamina I, marginal cells and other neurons with small round cell bodies showed calretinin-like immunoreactivity. A calretinin-immunoreactive plexus of nerve fibers was also found in this lamina. Lamina II was densely packed with calretinin-immunoreactive neuronal elements. The outer layer of lamina II was primarily composed of calretinin-immunoreactive neurons with a round or oval shape, whereas in the inner layer dorsoventrally orientated labeled neurons with spindle-shaped cell bodies were observed. Densely labeled neuropils with punctate profiles were also seen. By electron microscopy most of the labeled punctate profiles appeared to be dendrites, but axonal profiles were also found in smaller numbers. Labeled dendritic profiles established symmetric or asymmetric synapses with unlabeled axons and labeled axons established primarily symmetric synaptic contacts with unlabeled dendrites. Synaptic contacts between two calretinin-immunoreactive processes were observed infrequently.

Morphology and Distribution of the Vasoactive Intestinal Polypeptide (VIP)-Immunoreactive Amacrine Cells in the Mouse Retina / 대한해부학회지

Vasoactive intestinal polypeptide (VIP) is a neuroactive substance that is widely expressed in both non-mammalian and mammalian retinas. In this study, we immunocytochemically identified and investigated the VIP-containing neurons in the mouse retina, which has become an important model for the study of the structure and function of the mammalian retina, mainly because of the wide availability of transgenic animals. VIP immunoreactivity was observed in the somata of the amacrine cells in the inner nuclear layer (INL) and their varicose processes ramifying in strata 1 and 3 of the inner plexifrom layer (IPL). The distribution of VIP-immunoreactive (IR) amacrine cells showed a peak of 430 cells/mm2 in the central retina and minimum values of 50 cells/mm2 in the peripheral one. Double-label experiments demonstrated that all VIP-IR amacrine cells possessed GABA immunoreactivity. These results demonstrate that VIP-IR amacrine cells of the mouse retina make up a neurochemically and morphologically distinct subpopulation of the GABAergic amacrine cell population.

In vivo Study on the Japanese Encephalitis: Viral Localization and Histopathology in the Mouse Brain / 대한해부학회지

Japanese encephalitis is a potentially lethal disease of the central nervous system caused by infection with Japanese encephalitis virus (JEV). JEV is the most common cause of encephalitis over a large part of eastern Asia. To establish and characterize in vivo model to study the Japanese encephalitis, the immunohistochemical localization of JEV and the histopathological finding were investigated in the brains of young adult mice infected with JEV by intraperitoneal inoculation. JEV was localized to neurons in discrete regions of the brain. Histopathological finding showed typical pattern of acute viral encephalitis, such as inflammatory cell infiltration in brain parenchyme and perivascular cuffs of mononuclear cells. These results suggest that this in vivo system can be used to study the mechanism of virus entry into the brain, cell specific tropism, and pathophysiology in Japanese encephalitis.

Differentiation of Recoverin Immunoreactive Cone Bipolar Cells and Their Timing of Synaptic Formation with GABAergic Amacrine Cells in the Rat Retina / 대한해부학회지

Recoverin is a member of the large family of EF-hand calcium binding proteins (Baimbridge et al., 1992), and it is thought to be involved in the regulation of phosphodiesterase in photoreceptors and in the phosphorylation of activated rhodopsin (Polans et al., 1996). Although the functional significance of recoverin in cone bipolar cells is not fully understood, the antiserum against recoverin has been widely used to identify a certain population of cone bipolar cells (Milam et al., 1993; Sasso's Pognetto et al., 1994; Euler & W sle, 1995). GABA is well known to act as major neurotransmitters in the mammalian central nervous system including retina. This study was conducted to identify the development process of recoverin-labeled cone bipolar cells, and the timing points of synaptic formation of the labeled bipolar cells and GABAergic amacrine cells in the rat retina. The results were as follows; In the adult rat retina, recoverin-labeled cone bipolar cells were subdivided into twotypes; type 2 cells with axon terminal stratified in sublamina a of the inner plexiform layer (IPL), and type 8 cells with axon terminals stratified in sublamina b of the IPL. Recoverin-labeled cone bipolar cells began to appear from postnatal day 5. The axon terminals of recoverin-labeled type 2 cone bipolar cells stratified at postnatal day 10, while those of type 8 cone bipolar cells stratified at postnatal day 13. The axon terminals of type 2 cone bipolar cells made ribbon synapses onto GABAergic amacrine cells in the IPL at postnatal day 10. These results demonstrate that recoverin-labeled type 2 cone bipolar cells differentiate earlier than recoverin-labeled type 8 cone bipolar cells, and suggest that GABAergic amacrine cells may play important roles in visual processing of recoverin-labeled type 2 cone bipolar cells by making synapse onto these cells at early stage. Synapses between type 2 cone bipolar cells and GABAergic amacrine cells are formed about the time of postnatal day 10 for visual processing.

Anthropological Analysis of the Korean Skulls by Moire Contourography / 체질인류학회지

The patterns of the moir'e fringe were investigated in 178 modern Korean skulls (112 males and 66 females) using moir'e contourography. The analysis of fringe patterns was executed using image analyzer on the photographs taken from anterior, both lateral, posterior and superior aspects. In the anterior aspect, the center of fringe was the glabella. The cotyledon shape of fringe (type I) was the most frequently observed in males (77%), but reverse triangular shape (type II) and rhomboid shape of fringe (type III) were more frequently observed in females. In the lateral aspect, the euryon, the center of fringe, was located at higher (4 mm) and more lateral (3 mm) position in females than in males. The contour patterns were more irregular (type I) in males than in females where the stripes were arranged more concentrically (type II, III). In the posterior and superior aspects, there was no difference between males and females in the shape of fringe patterns. The relative position of the opisthocranion, the center of fringe in the posterior aspect, was high by 35 mm to eye -ear plane on the average in both sexes. The stripes in the superior aspect were arranged concentrically in both sexes, but wider in females than in males. The results of this nonmetrical study suggest that the analysis of the moir'e fringe patterns in the Korean skulls is a new method for sex discrimination in the field of forensic anthopology.

Distribution Pattern and Synaptic Circuitry of Cholinergic Neurons in the Rat Retina / 대한해부학회지

The role of acetylcholine as an excitatory neurotransmitter is well established, and cholinergic neurons appear to play an important role in the mammalian retinae. Though it has been reported that certain conventional and displaced amacrine cells are consistently labeled with anti-choline acetyltransferase antiserum in the mammalian retinae, little has been studied on the synaptic circuitry of cholinergic neurons to clarify mechanism of its action in the visual processing of the mammalian retinae. This study was conducted to localize cholinergic neurons and to define their synaptic circuitry in the rat retina by immunocytochemical method using anti-choline acetyltransferase antiserum. The results were as follows: 1. Cholinergic neurons of the rat retina were conventional amacrine cells located in the inner nuclear layer and displaced amacrine cells in the ganglion cell layer. 2. Cholinergic amacrine cells were branched in the middle of the sublamina a of the inner plexiform layer, and cholinergic displaced amacrine cells branched in the sublamina b, forming one prominent band, respectively. 3. Presynaptic processes to cholinergic amacrine cell processes were axon terminals of invaginating and flat cone bipolar cells, and unlabelled amacrine cell processes in the inner plexiform layer. Postsynaptic dyads at the ribbon synapses of axon terminals of cone bipolar cells were cholinergic amacrine cell process and dendrite of ganglion cell, cholinergic amacrine cell process and unlabelled amacrine cell process and cholinergic amacrine cell process and cholinergic amacrine cell process. In addition, cholinergic amacrine cell process formed postsynaptic monoad at the ribbon synapse. 4. Cholinergic amacrine cell processes made output conventional chemical synapses onto the dendrites of ganglion cells, unlabelled amacrine cell processes and cholinergic amacrine cell processes in the inner plexiform layer. These results demonstrate that (1) cholinergic neurons are conventional amacrine cells and displaced amacrine cells of which somata are located in the inner nuclear layer and ganglion cell layer, respectively, (2) cholinergic conventional amacrine cells are involved in OFF pathway, and cholinergic displaced amacrine cells play an important role in ON pathway in visual processing of lightness, and (3) acetylcholine released from cholinergic neurons by light excites directly ON and OFF ganglion cells or indirectly ON and OFF ganglion cells via non-cholinergic amacrine cells.