Med.Weter. environments,different specificity of antibody qual- when Ngb protein expression increased or decreased, ity employed,and immunological detection.These it was accompanied by a corresponding decrease or changes lead to the different expression and localiza- increase in H,O,content,indicating that Ngb was tion of neuroglobin which are suggested to influence a ROS scavenger.On the other hand,Nayak et al.(16) the adaptive potential of an organism(1).The pigment found that Ngb produced by cultured nerve cells in cortex is located in the outermost layer of the retina, vitro can reduce ROS levels,indicating that Ngb plays and its main function is to supply oxygen and nutri- a certain role in ROS elimination.Similarly,the cur- ents to the outer retina and absorb light scattering. rent results have shown that Ngb positive expression Therefore,the pigment super cortex is vulnerable to of different intensity was found in the rods and cones the photochemical damage of visible light,which leads and the super cortex pigment,indicating that Ngb may to the accumulation ofreactive oxygen species(ROS), have an important repairing effect on retinal damage and then produces oxidative stress reaction,resulting caused by light.However,further research is needed in cell apoptosis.However,Ngb can remove excessive to confirm this report.The main function of the retina ROS,maintain the oxygen balance of tissue cells,and is visual conduction in which photoreceptors convert protect cells from light damage,which may also be one the received photochemical signals into electrical of the reasons for the different Ngb expression.Other signals,and can be transmitted to the central nervous results confirmed that oxygen affinity and enhanced system through various neurons in the optic network auto-oxidation question the role in oxygen delivery membrane forming vision.The current study reported and proposed that the neuroprotective effect might be that Ngb was expressed in the cytoplasm,rods,cones, due to radical scavenging or activation of protection and other cells of the retinal microcytes and bipolar mechanisms (4). cells.However,other studies have shown (22)that Researchers are still debating the exact location of there are a large number of synaptic connections of Ngb.Ran et al.(19)found that there were strong Ngb adjacent binary neurons between ganglion cells,bi- mRNA hybridization signals in the inner and outer polar cells and rod-cone cells to transmit information, nuclear layers of rats.However.the study of Xu et al. which is one of the regions with the highest oxygen (25)showed that Ngb was not expressed in the outer consumption in the retina and also the region with nuclear layer.The results of this current study show concentrated mitochondria,so it is very sensitive to that Ngb is not distributed in the outer nuclear layer, oxidative damage caused by ROS.The high expression which is consistent with Xu's report.Some studies of Ngb as a ROS scavenger in mitochondria suggests documented that there might be certain differences in that Ngb is maintaining a high oxygen consumption the spatial distribution of Ngb mRNA and protein in the group that has more complex physiological functions retina.which makes the retinal structure of mammals in tissue metabolism.Ngb is expressed with different to be partitioned.Ngb mRNA is mainly distributed in intensity in each layer of the retina,and its expression the cell body,while Ngb is distributed in the protru- level is positively correlated with the demand for tis- sion,suggesting that the Ngb protein has a transport sue cells for oxygen.Moreover,Ngb is an endogenous process after translation.In the present research,the neuroprotective agent,and the expression level sig- positive distribution of Ngb in the outer segment of the nificantly increased due to hypoxia and ischemia of photoreceptor is rarely reported.The current results tissue cells(21).Roberts et al.(20)who employed the revealed the presence of Ngb in the outer segment of method of constructing a mathematical model showed the photoreceptor.This result may be related to the that the effect of Ngb is not in the oxygen storage, different animal species or may be closely related to but the oxygen may play a more important role in the the function of the outer segment of the photorecep- models to predict photoreceptors in the retina anoxic tor during the visual formation of the Bactrian camel area in the segment and inner plexiform layer which under extreme environmental conditions.Whether is involved in the functioning of high expression of Ngb is related to the adaptability of the environment Ngb area.The expression of Ngb strength with the re- remains to be studied.The Bactrian camel lives in an gional demand for oxygen utilization is closely related. extreme natural environment for a long time,with Moreover,the distribution of Ngb was also found in a dry climate and strong ultraviolet rays.A long period the optic nerve of the Bactrian camel,providing clues of illumination leads to excessive production of ROS for further research on the physiological function of and synthesis of lipid peroxidation product MDA, Ngb in protecting the optic nerve under extreme living resulting in retinal damage.Such lesions are mainly conditions.The histological study on the expression located in the regions of mitochondria in the retina distribution of Ngb in the retina of the Bactrian camel (20),because the inner segment of the photoreceptor showed that the expression distribution of Ngb in the is rich in mitochondria,while the outer segment is retina of the Bactrian camel was similar to that ofother rich in polyvalent unsaturated fatty acids and prone to mammals,but also had its own characteristics.The the formation of MDA,which may cause the rod and positive expression of Ngb in the outer segment of the cone layer to be damaged by ROS and MDA.Fordel photoreceptor of the Bactrian camel's retina enriches et al.(12)studied sh-sy5y nerve cells and found that the morphological information of the distribution of6 Med. Weter. environments, different specificity of antibody qual￾ity employed, and immunological detection. These changes lead to the different expression and localiza￾tion of neuroglobin which are suggested to influence the adaptive potential of an organism (1). The pigment cortex is located in the outermost layer of the retina, and its main function is to supply oxygen and nutri￾ents to the outer retina and absorb light scattering. Therefore, the pigment super cortex is vulnerable to the photochemical damage of visible light, which leads to the accumulation of reactive oxygen species (ROS), and then produces oxidative stress reaction, resulting in cell apoptosis. However, Ngb can remove excessive ROS, maintain the oxygen balance of tissue cells, and protect cells from light damage, which may also be one of the reasons for the different Ngb expression. Other results confirmed that oxygen affinity and enhanced auto-oxidation question the role in oxygen delivery and proposed that the neuroprotective effect might be due to radical scavenging or activation of protection mechanisms (4). Researchers are still debating the exact location of Ngb. Ran et al. (19) found that there were strong Ngb mRNA hybridization signals in the inner and outer nuclear layers of rats. However, the study of Xu et al. (25) showed that Ngb was not expressed in the outer nuclear layer. The results of this current study show that Ngb is not distributed in the outer nuclear layer, which is consistent with Xu’s report. Some studies documented that there might be certain differences in the spatial distribution of Ngb mRNA and protein in the retina, which makes the retinal structure of mammals to be partitioned. Ngb mRNA is mainly distributed in the cell body, while Ngb is distributed in the protru￾sion, suggesting that the Ngb protein has a transport process after translation. In the present research, the positive distribution of Ngb in the outer segment of the photoreceptor is rarely reported. The current results revealed the presence of Ngb in the outer segment of the photoreceptor. This result may be related to the different animal species or may be closely related to the function of the outer segment of the photorecep￾tor during the visual formation of the Bactrian camel under extreme environmental conditions. Whether Ngb is related to the adaptability of the environment remains to be studied. The Bactrian camel lives in an extreme natural environment for a long time, with a dry climate and strong ultraviolet rays. A long period of illumination leads to excessive production of ROS and synthesis of lipid peroxidation product MDA, resulting in retinal damage. Such lesions are mainly located in the regions of mitochondria in the retina (20), because the inner segment of the photoreceptor is rich in mitochondria, while the outer segment is rich in polyvalent unsaturated fatty acids and prone to the formation of MDA, which may cause the rod and cone layer to be damaged by ROS and MDA. Fordel et al. (12) studied sh-sy5y nerve cells and found that when Ngb protein expression increased or decreased, it was accompanied by a corresponding decrease or increase in H2 O2 content, indicating that Ngb was a ROS scavenger. On the other hand, Nayak et al. (16) found that Ngb produced by cultured nerve cells in vitro can reduce ROS levels, indicating that Ngb plays a certain role in ROS elimination. Similarly, the cur￾rent results have shown that Ngb positive expression of different intensity was found in the rods and cones and the super cortex pigment, indicating that Ngb may have an important repairing effect on retinal damage caused by light. However, further research is needed to confirm this report. The main function of the retina is visual conduction in which photoreceptors convert the received photochemical signals into electrical signals, and can be transmitted to the central nervous system through various neurons in the optic network membrane forming vision. The current study reported that Ngb was expressed in the cytoplasm, rods, cones, and other cells of the retinal microcytes and bipolar cells. However, other studies have shown (22) that there are a large number of synaptic connections of adjacent binary neurons between ganglion cells, bi￾polar cells and rod-cone cells to transmit information, which is one of the regions with the highest oxygen consumption in the retina and also the region with concentrated mitochondria, so it is very sensitive to oxidative damage caused by ROS. The high expression of Ngb as a ROS scavenger in mitochondria suggests that Ngb is maintaining a high oxygen consumption group that has more complex physiological functions in tissue metabolism. Ngb is expressed with different intensity in each layer of the retina, and its expression level is positively correlated with the demand for tis￾sue cells for oxygen. Moreover, Ngb is an endogenous neuroprotective agent, and the expression level sig￾nificantly increased due to hypoxia and ischemia of tissue cells (21). Roberts et al. (20) who employed the method of constructing a mathematical model showed that the effect of Ngb is not in the oxygen storage, but the oxygen may play a more important role in the models to predict photoreceptors in the retina anoxic area in the segment and inner plexiform layer which is involved in the functioning of high expression of Ngb area. The expression of Ngb strength with the re￾gional demand for oxygen utilization is closely related. Moreover, the distribution of Ngb was also found in the optic nerve of the Bactrian camel, providing clues for further research on the physiological function of Ngb in protecting the optic nerve under extreme living conditions. The histological study on the expression distribution of Ngb in the retina of the Bactrian camel showed that the expression distribution of Ngb in the retina of the Bactrian camel was similar to that of other mammals, but also had its own characteristics. The positive expression of Ngb in the outer segment of the photoreceptor of the Bactrian camel’s retina enriches the morphological information of the distribution of