Development of a new cerebral ischemia reperfusion model of Mongolian gerbils and standardized evaluation system

Background:The Mongolian gerbil is an excellent laboratory animal for preparing the cerebral ischemia model due to its inherent deficiency in the circle of Willis.However,the low incidence and unpredictability of symptoms are caused by numerous complex variant types of the circle.Additionally,the lack of an evaluation system for the cer-ebral ischemia/reperfusion(I/R)model of gerbils has shackled the application of this model.Methods:We created a symptom-oriented principle and detailed neurobehavioral scoring criteria.At different time points of reperfusion,we analyzed the alteration in locomotion by rotarod test and grip force score,infarct volume by triphenyltetrazo-lium chloride(TTC)staining,neuron loss using Nissl staining,and histological charac-teristics using hematoxylin-eosin(H&E)straining.Results:With a successful model rate of 56%,32 of the 57 gerbils operated by our method harbored typical features of cerebral I/R injury,and the mortality rate in the male gerbils was significantly higher than that in the female gerbils.The suc-cessfully prepared I/R gerbils demonstrated a significant reduction in motility and grip strength at 1 day after reperfusion;formed obvious infarction;exhibited typi-cal pathological features,such as tissue edema,neuronal atrophy and death,and vacuolated structures;and were partially recovered with the extension of reperfu-sion time.Conclusion:This study developed a new method for the unilateral common carotid artery ligation I/R model of gerbil and established a standardized evaluation system for this model,which could provide a new cerebral I/R model of gerbils with more practical applications.

H pylori infection causes chronic pancreatitis in Mongolian gerbils

AIM： To investigate whether chronic H pylori infection has the potential to induce pancreatitis in the Mongolian gerbil model, and whether it is dependent on an intact type Ⅳ secretion system. METHODS： Mongolian gerbils were infected with wild type （WT） H pylori type Ⅰ strain B128 or its isogenic mutant B128 △cag γ （defective type Ⅳ secretion）. After seven months of infection, H pylori was reisolated from antrum and corpus and Hpylori DNA was analyzed by seminested polymerase chain reaction （PCR）. Inflammation and histological changes were documented in the gastric antrum, corpus, and pancreas by immunohistochemistry. Cytokine mRNA, gastric pH, plasma gastrin, amylase, lipase, and glucose levels were determined. RESULTS： The H pylori infection rate was 95%. Eight infected animals, but none of the uninfected group, developed transmural inflammation and chronic pancreatitis. Extensive interstitial fibrosis and inflammation of the pancreatic lobe adjacent to the antrum was confirmed by trichrome stain, and immuno-histochemically. Pro-inflammatory cytokine mRNA was significantly increased in the antral mucosa of all infected gerbils. In the corpus, only cytokine levels of WT-infected animals andthose developing transmural inflammation and pancreatitis were significantly increased. Levels of lipase, but not glucose or amylase levels, were significantly reduced in the pancreatitis group. H pylori DNA was detected in infected antral and corpus tissue,but not in the pancreas CONCLUSION： H pylori infection is able to induce chronic pancreatitis in Mongolian gerbils independently of the type Ⅳ secretion system, probably by an indirect mechanism associated with a penetrating ulcer.

Short-term Celecoxib intervention is a safe and effective chemopreventive for gastric carcinogenesis based on a Mongolian gerbil model

AIM： To evaluate the optimal intervention point of a selective cyclooxygenase-2 （COX-2） inhibitor, Celecoxib, for inhibiting Helicobacter pylori （H pylori-associated gastric carcinogenesis in Mongolian gerbils （MGs）.METHODS： One hundred and twelve MGs were divided into six groups （A-F）. One hundred gerbils were inoculated with H pylor/（groups A-E）. Twelve gerbils were inoculated with vehicle broth only （group F）. After 4 wk, they were given N＇-methyl-N＇ -nitro-N-nitroso-guanidine （MNNG） （50 μg/mL） in the drinking water for 20 wk. in groups B-E, the animals were given the stock Celecoxib （10 mg/kg per day） diet from the 21st, 31st, 21st and 41st week respectively. The periods of administering Celecoxib were 30, 20, 20, and 15 wk respectively. On the 51st week, the animals were sacrificed for histological examination. Local PCNA expression was examined by the immunohistochemistry method. The expression of COX-2 protein was assessed by Western Blot. Analysis used the 2 test. The difference was regarded as significant when P value was less than 0.05. RESULTS： Seventeen percent （17/100） of H pyloriinfected MGs developed gastric cancer. All of these lesions were well-differentiated adenocarcinoma. The incidence rates of adenocarcinoma in groups A-F were 40%, 0%, 0%, 20%, 25%, and 0% respectively. The inflammatory scores were higher in group B than in other groups. There was no inflammatory response noted in group F. Celecoxib treatment resulted in a significant reduction in the proliferation of H pyloriinfected mucosal cells （groups B, C and D） （P 〈 0.01）. The expression of COX-2 protein was significantly attenuated in the groups which were Celecoxib-treated for more than 20 wk （groups B, C, D）. The groups treated with Celecoxib had a significantly lower rate of advanced gastric cancer （34% vs 75%, P 〈 0.001） There were no sudden deaths in any of the groups. CONCLUSION： Short-term treatment with Celecoxib has an anti-carcinogenic effect, and resulted in less severe inflammation and inhibited the invasive degree of gastric cancer.

Anti-Helicobacter pylori therapy significantly reduces Helicobacter py/ori-Induced gastric mucosal damage in Mongolian gerbils

AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pylori therapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes. METHODS: We used 6-wk-old male gerbils orally inoculated with H pylori (ATCC43504, 2×108 CFU/mL). Seven weeks after H pylori inoculation, the animals of study group received 4 d' anti-H pylori triple therapy (H pylori-eradicated group). Seven days later, all animals of the H pylori-eradicated and control groups (H pylori-infected & H pylori-uninfected groups) were sacrificed. We examined gastric mucosal lesions macroscopically, studied gastritis microscopically and determined the stomach weight ratio, myeloperoxidase (MPO) activity and prostaglandin (PG) E2 level. RESULTS: The results showed that both macroscopic and histological gastric damages were significantly less in H pylori-eradicated group than H pylori-infected group. Stomach weight ratio, MPO activity and PGE2 levels were significantly higher in H pylori-infected group than those in the other two groups. CONCLUSION: Four days' anti-H pylori therapy was effective in the improvement of H pylori-induced gastric lesions in Mongolian gerbils.

Helicobacter pyloristrain-specific modulation of gastric inflammation in Mongolian gerbils

AIM: The cag pathogenicity island (PAI) is one of potential virulence determinants of Helicobacter pylori. The Mongolian gerbil is a suitable experimental animal for the screening of virulence factors of H pylori.METHODS: Five-week-old Mongolian gerbils were inoculated with a standard H pylori strain (ATCC 43504)possessing the cag PAI or a clinical isolate lacking the genes' cluster (OHPC-0002). The animals were killed at 2, 4, 8, 24 and 48 wk after inoculation (n = 5 each), and macroscopic and histopathological findings in the stomachs were compared.RESULTS: In gerbils infected with ATCC 43504, a more severe degree of infiltration of polynuclear and mononuclear cells and lymphoid follicles was observed from 4 wk after inoculation compared to gerbils infected with OHPC-0002 especially in the antrum and transitional zone from the fundic to pyloric gland area. In addition,glandular atrophy, intestinal metaplasia, gastric ulcer and hyperplastic polyps were noted in gerbils infected with ATCC 43504, whereas only mild gastric erosions occurred in those infected with OHPC-0002.CONCLUSION: Our results indicate that the cag PAI could be directly involved in gastric immune and inflammatory responses in the Mongolian gerbils, leading to a more advanced gastric disease.

Tyrosinase (Tyr) Gene Mutation in Albino Mongolian Gerbil (Meriones unguiculatus)

Tyrosinase is encoded by the Tyr (c or albino) locus and is the key enzyme in pigment biosynthesis. Loss of function of this enzyme caused by gene mutation results in albinism. Most cases of albinism are caused by missense mutations of tyrosinase. Albino mutations in Tyr have been identified in various animals, including human, mouse, rat, rabbit, cattle, cat, and ferret, but not in gerbil. We created two new gerbil strains: MON/Num/a (inbred agouti phenotype) and MON/Num/c (albino phenotype). Here, we report that four nucleotide substitutions in the Tyr gene caused two missense mutations in amino acids in the albino gerbil: a G-to-A mutation at position 204 in exon 1 caused R77H, and A-to-G at position 1392 and G-to-T at position 1393 in exon 5 caused Q473R. The substitution at position 1408 in exon 5 was silent. These missense mutations are conserved in all albino phenotypes we tested. Therefore, we suggest that these mutations are responsible for albinism in gerbil.

INDUCTION OF GASTRIC INTRAEPITHELIAL NEOPLASIA OF GLANDULAR STOMACH OF MONGOLIAN GERBILS BY ELICOBACTER PYLORI

Objective： To setup an animal model of gastric carcinogenesis by Helicobacter pylori （Hp） for basic, prevention and therapeutic research of Hp-related diseases. Methods： 22 young male Mongolian gerbils were administrated with suspension of Hp strain TN2 by intragastric garage for 5 consecutive times （4×10^8 CFU/time, 1 time/4 days）. 10 male gerbils were used as negative control. Two infected gerbils were killed at 10, 20, and 30 weeks, respectively, after inoculation to monitor the development of gastric lesions. Other animals were killed at 40 experimental weeks. Pathological changes of glandular stomach were examined histologically. Results： Gastric intraepithelial neoplasias （GIN） and low-grade dysplasias were observed only in the pyloric antrum of Hp-treated gerbils （3 and 2 ones, respectively）, but not in control group （5/13 vs. 0/10, P〈0.04）. High incidence of chronic active gastritis and chronic atrophic gastritis were observed in Hp-treated animals （10/13, 76.9%）. Low incidence of chronic atrophic gastritis was also detected in negative control gerbils （3/10, 30%; P〈0.04）. Conclusion： Hp inoculation could induce chronic inflammation and malignant lesions of the glandular stomach of Mongolian gerbils conveniently.

Experimental infection of Z:ZCLA Mongolian gerbils with human hepatitis E virus

AIM:To investigate whether Z:ZCLA Mongolian gerbils are readily susceptible to infection by human hepatitis E virus(HEV).METHODS:Z:ZCLA Mongolian gerbils were infected with a clinical HEV strain isolated from an acutehepati tis E patient,and virus pathogenesis was assessed in this host.Non-infected gerbils served as the control group.Feces samples from gerbils were collected weekly for reverse transcription-nested polymerase chain reaction.Serum anti-HEV Ig G and alanine aminotransferase(ALT) were detected by enzyme linked immunosorbent assay.At sacrifice,each animal's liver,spleen and kidney were collected for histopathologic examination.RESULTS:HEV-infected gerbils showed fatigue,with histopathological changes observed in the liver,spleen and kidney.HEV RNA was detected in fecal samples taken at day 7 after inoculation and the detectable levels lasted out to day 42 after inoculation.Interestingly,ALT levels were only moderately increased in the HEV-infected animals compared with the noninfected control group.CONCLUSION:Z:ZCLA Mongolian gerbils are susceptible to human HEV.

The effect of mast cell on the induction of Helicobacter pylori infection in Mongolian gerbils

INTRODUCTION Since 1982,Helicobacter pylori(Hp) has been successfully isolated and cultured,and the fact many diseases such as gastritis,peptic ulcer,gastric carcinoma

Effects of adaptation to handling on the circadian rhythmicity of blood solutes in Mongolian gerbils

The Mongolian gerbil has been widely used in many research fields and has been reported to be a diurnal laboratory animal. The circadian rhythmicity of these gerbils was investigated in the present study by measuring two hormones that show daily oscillations, cortisol and ACTH, in serum using ELISA kits. The levels of the two hormones were highest at 8:00 am and their rhythmic changes were similar to those in humans. In addition, the influence of stress of handling and blood collection on the physiological parameters of the gerbils was examined. After adaptation to handling for 1 week, some serum parameters in the animals changed. Handling and blood collection did not impact significantly on the following parameters: creatine kinase (CK), lactate dehydrogenase (LD), alanine aminotransferase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN), and albumin (ALB). However, blood glucose (GLU), total protein (TP) and globulin (GLB) significantly increased while creatinine (CRE) and albumin/globulin (A/G) significantly decreased after adaptation. This work further confirms that the Mongolian gerbil is a diurnal animal and also indicates that a suitable adaptation procedure is necessary for getting reliable results when performing experiments using these animals.

Effects of levonorgestrel-quinestrol(EP-1)treatment on Mongolian gerbil wild populations:a case study

Rodent pest population outbreaks occur frequently in grassland ecosystems in northern China.The Mongolian gerbil(Meriones unguiculatus)is a dominant pest rodent which is distributed across the semi-desert grasslands of Inner Mongolia,China.In 2009,we studied the contraceptive effect of levonorgestrel-quinestrol(EP-1),concentration 50 ppm,on a wild Mongolian gerbil population.The one-off contraceptive treatment was compared with a control group using a semi-monthly live trapping method in the Ordos Semi-desert Grassland Region of Inner Mongolia.The results show that juveniles were not recruited in spring in the treatment group.Ratios of juveniles in the control and treatment groups showed significant semi-monthly differences from spring to summer(one-way ANOVA,F_(2,14)=7.53,P<0.05).Between both groups,annual fluctuations of juvenile and total population densities were significantly different respectively(F_(2,14)=4.64,P<0.05;F_(2,18)=7.72,P<0.05).The contraceptive EP-1 delayed the normal reproductive pattern of Mongolian gerbil populations.This suppressed birth rates of gerbil populations,reduced their densities,and changed their age structures.The period of EP-1 baiting should be extended but it could be an ideal method for controlling Mongolian gerbil populations during each breeding season.

Temporal and spatial distribution characteristics in the natural plague foci of Chinese Mongolian gerbils based on spatial autocorrelation

Background:The nest flea index of Meriones unguiculatus is a critical indicator for the prevention and control of plague,which can be used not only to detect the spatial and temporal distributions of Meriones unguiculatus,but also to reveal its cluster rule.This research detected the temporal and spatial distribution characteristics of the plague natural foci of Mongolian gerbils by body flea index from 2005 to 2014,in order to predict plague outbreaks.Methods:Global spatial autocorrelation was used to describe the entire spatial distribution pattern of the body flea index in the natural plague foci of typical Chinese Mongolian gerbils.Cluster and outlier analysis and hot spot analysis were also used to detect the intensity of clusters based on geographic information system methods.The quantity of M.unguiculatus nest fleas in the sentinel surveillance sites from 2005 to 2014 and host density data of the study area from 2005 to 2010 used in this study were provided by Chinese Center for Disease Control and Prevention.Results:The epidemic focus regions of the Mongolian gerbils remain the same as the hot spot regions relating to the body flea index.High clustering areas possess a similar pattern as the distribution pattern of the body flea index indicating that the transmission risk of plague is relatively high.In terms of time series,the area of the epidemic focus gradually increased from 2005 to 2007,declined rapidly in 2008 and 2009,and then decreased slowly and began trending towards stability from 2009 to 2014.For the spatial change,the epidemic focus regions began moving northward from the southwest epidemic focus of the Mongolian gerbils from 2005 to 2007,and then moved from north to south in 2007 and 2008.Conclusions:The body flea index of Chinese gerbil foci reveals significant spatial and temporal aggregation characteristics through the employing of spatial autocorrelation.The diversity of temporary and spatial distribution is mainly affected by seasonal variation,the human activity and natural factors.

Impairment of cellular and humoral immunity in overweight Mongolian gerbils (Meriones unguiculatus)

Animal immunity is usually impaired in obesity.We know little about the effect of being overweight or obese on the immune function of wild rodents.The present study is aimed to test the hypothesis that immunity is suppressed in overweight Mongolian gerbils(Meriones unguiculatus).In the study,16 overweight(body mass:90.8-127.6 g)and 16 lean gerbils(body mass:60.5-77.7 g)were randomly selected from a total of 174 male gerbils(body mass range:55.8-144.7 g).Half of the overweight and lean males were injected with sterile saline;the others were immunochallenged(IC)with phytohaemagglutinin and keyhole limpet hemocyanin to assess cellular and humoral immunity,respectively.Body fat mass,wet and dry spleen mass,leukocyte counts,blood glucose levels and serum leptin levels were significantly higher in the overweight gerbils than in the lean gerbils.However,phytohemagglutinin response indicative of cellular immunity and immunoglobulin G concentrations was significantly lower in the IC overweight gerbils than in the IC lean gerbils.These results indicate that cellular and humoral immunity are impaired in the overweight gerbils.Excessive body fat mass,higher leukocyte counts and serum leptin levels imply that overweight gerbils are in a low grade inflammatory state.

Role of transient receptor potential vanilloid-1 in behavioral thermoregulation of the Mongolian gerbil Meriones unguiculatus

Ambient temperature considerably affects the physiology and behavior of mammals.Thermosensory and thermoregulatory abilities play an important role in the response to changing ambient temperature in endotherms.However,the molecular mechanisms of behavioral thermoregulation remain poorly understood.Transient receptor potential vanilloid-1(TRPV1)is activated by changes in ambient temperature and is involved in acute thermoregulation.Here,we aimed to determine whether TRPV1 is involved in behavioral thermoregulation in wild rodents by conducting 2 experiments.In the first,42 adult Mongolian gerbils(Meriones unguiculatus;14 per treatment)were randomly assigned to 3 housing temperatures(4,23,and 36℃for 4 weeks.In the second,20 gerbils(10 per treatment)were randomly injected with capsaicin(TRPV1 agonist)or AMG517(TRPV1 antagonist).The results showed a significant decrease in food intake and non-shivering thermogenesis in the gerbils housed at 36℃.Additionally,there was a significant increase in the preference of gerbils housed at 4℃ to low temperatures.The expression of TRPV1 protein in the brown adipose tissue(BAT)and liver was significantly positively correlated with that of protein kinase A(PKA).The expression of TRPV1 and PKA proteins in the BAT was positively correlated with the temperature preference of the gerbils.The gerbils injected with capsaicin preferred significantly lower temperatures than the control group gerbils.These findings suggest that TRPV1 and PKA are involved in behavioral thermoregulation in Mongolian gerbils.

Morphological properties of medial amygdala-projecting retinal ganglion cells in the Mongolian gerbil

The amygdala is a limbic structure that is involved in many brain functions, including emotion, learning and memory. It has been reported that melanopsin-expressing retinal ganglion cells(ip RGCs) innervate the medial amygdala(Me A). However, whether conventional RGCs(c RGCs) project to the Me A remains unknown. The goal of this study was to determine if c RGCs project to the Me A and to determine the morphological properties of Me A-projecting RGCs(Me A-RGCs). Retrogradely labeled RGCs in whole-mount retinas were intracellularly injected to reveal their dendritic morphologies. Immunohistochemical staining was performed to selectively label ip RGCs(Me A-ip RGCs) and c RGCs(Me A-c RGCs). The results showed that 95.7% of the retrogradely labeled cells were c RGCs and that the rest were ip RGCs. Specifically, Me A-c RGCs consist of two morphological types. The majority of them exhibit small but dense dendritic fields and diffuse ramification patterns as previously reported in RG_(B2)(95%), while the rest exhibit small but sparse dendritic branching patterns resembling those of RG_(B3) cells(5%). Me Aip RGCs consist of M1 and M2 subtypes. The Me A-RGCs showed an even retinal distribution patterns. The soma and dendritic field sizes of the Me A-RGCs did not vary with eccentricity. In conclusion, the present results suggest that Me A-RGCs are structurally heterogeneous. These direct RGCs that input to the Me A could be important for regulating amygdala functions.

Time-course pattern of neuronal loss and gliosis in gerbil hippocampi following mild, severe, or lethal transient global cerebral ischemia

Transient ischemia in the whole brain leads to neuronal loss/death in vulnerable brain regions. The striatum, neocortex and hippocampus selectively loose specific neurons after transient ischemia. Just 5 minutes of transient ischemia can cause pyramidal neuronal death in the hippocampal cornu ammonis (CA) 1 field at 4 days after transient ischemia. In this study, we investigated the effects of 5-minute (mild), 15-minute (severe), and 20-minute (lethal) transient ischemia by bilateral common carotid artery occlusion (BCCAO) on behavioral change and neuronal death and gliosis (astrocytosis and microgliosis) in gerbil hippocampal subregions (CA1-3 region and dentate gyrus). We performed spontaneous motor activity test to evaluate gerbil locomotor activity, cresyl violet staining to detect cellular distribution, neuronal nuclei immunohistochemistry to detect neuronal distribution, and Fluoro-Jade B histofluorescence to evaluate neuronal death. We also conducted immunohistochemical staining for glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1 (Ibal) to evaluate astrocytosis and microgliosis, respectively. Animals subjected to 20-minute BCCAO died in at least 2 days. BCCAO for 15 minutes led to pyramidal cell death in hippocampal CA1-3 region 2 days later and granule cell death in hippocampal de匚tate gyrus 5 days later. Similar results were not found in animals subjected to 5-minute BCCAO. Gliosis was much more rapidly and severely progressed in animals subjected to 15-minute BCCAO than in those subjected to 5- minute BCCAO. Our results indicate that neuronal loss in the hippocampal formation following transient ischemia is significantly different according to regions and severity of transient ischemia. The experimental protocol was approved by Institutional Animal Care and Use Committee (AICUC) of Kangwon National University (approval No. KW-180124-1) on May 22, 2018.

长爪沙鼠不同感音神经性耳聋模型的建立及比较

目的利用不同的耳毒性药物建立长爪沙鼠感音神经性耳聋模型,并对3种模型进行比较分析,为感音神经性耳聋的研究提供精准的动物模型。方法选择长爪沙鼠,建立硫酸卡那霉素和呋塞米联用(KM+Fur)、新霉素(Neo)及哇巴因(Oua)3种耳毒性药物的感音神经性耳聋模型,通过听性脑干反应(ABR)和耳蜗组织形态学检测,比较分析不同耳毒性药物的损伤特点。结果KM+Fur造模后,与对照组(14.00±1.80)相比,该组(71.00±5.26)长爪沙鼠的听力阈值显著上升,耳蜗HCs大量损伤,而SGNs无明显损伤;Neo造模后,与对照组相比,40 mmol·L^(-1) Neo仅影响沙鼠高频32 kHz时听力阈值(60.00±8.66),无明显的组织学改变;而100 mmol·L^(-1) Neo组的沙鼠各频率听力阈值均显著上升,且耳蜗HCs及SGNs均严重受损;Oua造模后,1 mmol·L^(-1) Oua和10 mmol·L^(-1) Oua均可引起沙鼠各频率听力阈值显著上升,但损伤范围不同,10 mmol·L^(-1) Oua使HCs和SGNs均严重受损,而1 mmol·L^(-1) Oua仅造成耳蜗SGNs损伤。结论利用KM+Fur可建立长爪沙鼠HCs特异性受损的感音神经性耳聋模型;40 mmol·L^(-1) Neo可建立高频区听功能损伤的感音神经性耳聋模型;利用100 mmol·L^(-1) Neo和10 mmol·L^(-1) Oua可以建立长爪沙鼠HCs和SGNs均受损的感音神经性耳聋模型;利用1 mmol·L^(-1) Oua可以建立长爪沙鼠耳蜗SGNs特异性受损的耳聋模型。

不同周龄段雄性长爪沙鼠肾小体的形态变化

目的通过观察比较不同周龄段的雄性长爪沙鼠的肾脏在最大纵切面上肾小体的变化,初步探索不同周龄段雄性长爪沙鼠肾小体可能存在的变化规律,为选择雄性长爪沙鼠用于肾病相关致病机制及药物筛选等研究提供基础数据支持。方法分别取12周龄、48周龄、72周龄3个周龄段的雄性长爪沙鼠肾脏,从最大冠状面纵切后制成肾脏组织切片;苏木精-伊红染色后,全景扫描成电子组织切片,利用CaseViewer拍摄最大纵切面上肾小体图片,并测量肾小体及其所包含的肾小球、肾小囊面积;使用IBMSPSSStatistics27进行统计分析,使用GraphPad Prism 8制作图表。结果与12周龄相比,48周龄时肾小体(P=0.029)、肾小球(P=0.001)的面积均显著增大,肾小囊面积没有明显变化(P=0.478),肾小球在其肾小体中的面积占比有增大趋势,但差异无统计学意义(P=0.163);与48周龄相比,72周龄时肾小体、肾小球和肾小囊面积均显著增大(P<0.001),但肾小球在其肾小体中的面积占比显著减小(P<0.001)。结论12~72周龄的雄性长爪沙鼠肾小体持续增大,在这个增大过程中可能存在一定规律,即肾小球与肾小体的增大趋势相对一致;而肾小囊与肾小体相比,其增大趋势存在一定滞后性,推测肾小体增大主要是由肾小球增大引起,进而导致肾小囊被动增大造成的;肾小体增大可能是通过多次“肾小球增大–引发肾小囊增大”完成。

长爪沙鼠性成熟前后生殖系统的发育情况

目的深入探究长爪沙鼠性成熟过程中生殖系统的发育情况,为其性成熟的确切时间提供直接研究证据。方法本研究选取6~14周龄长爪沙鼠共150只,按6、8、10、12和14周龄分为5组,每组雌雄各15只,称量体质量并采集卵巢、子宫、睾丸、附睾样本,测量各样本组织湿重并计算脏器指数;镜下观察卵巢外观形态;细胞计数仪检测精子数量;每组随机选取6个样本进行HE染色,观察卵巢、睾丸、附睾的组织发育情况。结果雌性沙鼠10周龄时卵巢湿重和卵巢指数均明显增加,且10~14周龄期间无明显变化,子宫湿重和子宫指数均呈阶段性变化;镜下观察外观,10周龄、12周龄、14周龄组黄体发生率分别为46.7%、60%、73.3%;组织切片显示,10周龄起可见明显黄体。雄性沙鼠在6~10周龄阶段睾丸湿重随周龄的增长而逐渐增加,10周龄后无明显变化;睾丸指数在8及12周龄时明显增加,14周龄时明显减小;6~12周龄阶段附睾湿重和附睾指数均随周龄的增长而逐渐增加,14周龄时附睾湿重无明显变化,附睾指数明显减小。细胞计数仪结果显示,6周龄时精子数量为0,10周龄与8周龄相比,附睾内精子数量明显增加,10~14周龄期间无明显变化。组织切片显示,8周龄起,睾丸和附睾内开始出现少量精子,10周龄起可见大量精子。结论随着周龄的增长,雌性沙鼠卵巢在10周龄左右卵泡开始发育成熟并排出卵子,达到性成熟,具备繁殖能力。雄性沙鼠8周龄左右开始产生精子,进入初情期,10周龄左右睾丸发育稳定,精子达最大数量,达到性成熟,此后附睾继续发育,12周龄左右发育稳定。