| The Harderian gland(HG)is a sub-lacrimal gland located in the eye of a terrestrial vertebrate,belonging to the exocrine gland.Generally speaking,it is located in the back of the orbit and close to the back of the eye in mammal.Studies have shown that HG has a developed catheter system,including the intrinsic parenchymal catheters,the external parenchymal catheters and the end formed by cells besides the morphosis as well as secretion patterns differ among cells.HG has a variety of biological functions because of its rich catheter system,diverse interstitial cells and contents.Rodents have larger glands containing lots of fat,porphyrins and indole.The glands are secreted through the catheter,and the catheter opens directly to the nictitating membrane.The shape and function are different among different species while there are many common features in the HG of Rodents.In particular,there are lots of obvious sexual dimorphisms in the gland of many species and this is reflected in the shape,cell composition,its contents and many other aspects of the HG.The function of the HG is not yet clear now.The reported features include eye lubrication,osmotic adjustment,light protection and body temperature regulation.In addition,the HG also has immune,secretory growth factor,involved in seasonal reproductive regulation and other important functions.Cricetulus barabensis is one of the main harmful rats of farmland in north China with its Strong viability and high reproductive capacity.It belongs to the typical seasonal breeding animal and its reproductive behavior is obviously affected by the influence of season and light.Previous studies have shown that C.barabensis is a good material for studying the morphology and function of HG which has appropriate size,clear location and an easy way to be acquired.In order to explore: Whether the structure of the HG of the C.barabensis;Whether the functional activity of the HG is regulated by the photoperiod and has seasonal variation;How is its internal molecular regulation mechanism.In this study,we choose C.barabensis as the animal material,using methods of morphological measurements,paraffin sections and H-E staining,toluidine blue staining,immunohistochemistry and RT-PCR to observe the morphology and organization structure and record the number of estrogen receptor beta(ERB)positive cells and somatostatin(SS)positive cells,to explore the structure of the HG of the C.barabensis and to detect the seasonal and photoperiodic expression of ERB and SS in HG.The results show that:(1)HG length of the females was shorter than that of males,but the weight of the females was heavier than that of males,but there was no significant difference in sex,and significant seasonal difference in length and weight;(2)The results of HE stainingshowed that with the growth of the age,the acinar increased and the acinar gap and lobular gap decreased gradually in the HG of the C.barabensis.The acinar gap became smaller when the sub-adult was reached while the lobular gap became smaller when the adult was reached.Followed by alveolar loosening,acinar gap and lobular gap gradually increased.There was no obvious in male and female tissues.(3)Toluidine blue staining showed that mast cells were heterogeneous staining,the cytoplasm was dark purple and the nucleus was colorless.Different fixative,dyeing solution and different staining methods have an impact on the staining of mast cells.The most suitable fixative and dyeing liquid is 10﹪formalin and toluidine blue classic.There are differences in the number of mast cells in the HG of the male and female individuals of the C.barabensis,but the difference was not significant.(4)RT-PCR method showed that ERB gene expression was found in HG of C.barabensis.Immunohistochemical methods showed that the ERB-positive cells were circular,oval or nearly oval.The nucleus is not colored and the cytoplasm is dark brown;the number of ERB-positive cells in the females was significantly higher than that in male individuals.(5)SS immunohistochemistry showed that the number of SS-positive cells in female was slightly larger than that in male,but the difference was not significant.Individuals show that the number of SS-positive cells is different in the four seasons,the largest in spring,followed by autumn,followed by winter and summer,both males and females show a similar trend;There was no significant difference in the expression of male and female positive cells in the same season;The number of SS-positive cells changed after photoperiod treatment which males were significantly larger than females;There was no significant difference between the long day(LD)and the moderate day(MD),and there was no significant difference between the MD and the short day(SD),but the LD was significantly larger than the SD.The comparison of LD,MD and SD shows that there is no significant difference in the two adjacent MD periods,but LD is significantly larger than SD.The number of positive cells in male and female was similar in middle MD.In the LD and SD,the number of positive cells of males was more than that of females.(6)There was no significant difference in SS hormone concentration between male and female individuals;there was no significant difference in SS concentrations for the four seasons except for summer,it was significantly lower than the other three seasons.The above results suggest that:(1)There was no significant difference from sex and significant seasonal difference in the length and weight of the C.barabensis.(2)The function of the HG of the C.barabensis is affected by a variety of factors.Estrogens and somatostatin are important molecules that regulate the activity of HG.Because ERB and SS are expressed in the HG,and the expression is affected by a variety of factors.The SS expression has significant seasonal difference,and the longer the illumination time expressed by the more quantity,theresults suggest photoperiod changes may regulate the HG growth and development and function by SS.The results of the study will help to deepen the understanding of the structure of HG,lay a foundation for further study of the regulation of HG function and provide basic data for the comprehensive prevention and control of rodents. |
