Effect Of Exogenous Hormones On Lymphatic Stomata In Ovarian Bursa And Research On The Development Of Ovarian Bursal Stomata

Background The ovarian mesentery is defined as the peritoneum connecting the ovary with the ovarian broad ligament. In some rodents it forms a capsule that encloses the ovary and contains fluid within the cavity. The capsule in rodents is termed ovarian bursa. The fluid in ovarian bursal cavity plays an important role in maintaining the balance of ovarian microenvironment. Shinohara first described the presence of the lymphatic stomata in the ovarian bursa of hamster and indicated that the lymphatic stomata participated in the function of drainage fluid from the ovarian bursal cavity to the lymphatic and vascular system.However, there were few researches concerning on the lymphatic stomata in the ovarian bursa. Followed by Shinohara, Dobroszynska reported the existence of the lymphatic stomata in the ovarian bursa of European beaver. It has been proved that the ovarian bursas of guinea pig and mice also had lymphatic stomata connecting the bursal cavity with lymphatic lumen recently. But there was little report about the regulation of steroid hormones on lymphatic stomata and the development of lymphatic stomata in the ovarian bursa.Objective (1) To study the ovarian bursa and the lymphatic stomata in ovarianbursa of mice. (2) To investigate the regulation of steroid hormones on lymphatic stomata and estrogen receptor in the mesothelial cells of ovarian bursa. (3) The research of the development of ovarian bursa and lymphatic stomata in guinea pig.Methods (1) Ovarian bursa and the lymphatic stomata of ovarian bursa in mice were examined with light microscope, scanning electron microscope (SEM), NaOH-digested SEM and the transmission electron microscope (TEM). (2) Mice were randomly divided into three groups, i.e. estrogen, androgen and control (saline) groups, and SEM and TEM were used for ultrastructural study. Trypan blue was used as a tracer for measuring the absorptive rate of the stomata. And estrogen receptor was studied by using immuo-colloid golden technology. (3) The ovarian bursa of guinea pig, at stage from embryonic day 60 to the adult, was observed by SEM, the area of lymphatic stomata was counted by the Elescope computer image processing system.ResultThe ultrastructure of ovarian bursal lymphatic drainage unitsThe ovary was surrounded by a complete closed capsule termed of the ovarian bursa. The ovarian bursal cavity was connected with the lymphatic system by the ovarian bursal lymphatic drainage unit, which is composed of lymphatice stomata, channel in connective tissue and the gap between lymphatic endothelial cells. It was first found there existed estrogen receptor in the nuclei of mesothelial cells on the inner layer ovarian bursa.Changes in the absorption function, ultrastructure and estrogen receptor expression level in lymphatic stomata and mesothelial cellsIn the experiment, the absorption of lymphatic stomata was enhanced in estrogen group and decreased in androgen group, which compared with control. The average areaof lymphatic stomata opened larger and numerous vesicles with various sizes were observed in the mesothelial cells on the inner layer of ovarian bursa in estrogen group. However, the lymphatic stomata showed smaller in size in androgen group. The expression level of estrogen receptor was down regulated by estrogen and slightly up-regulated with androgen.The development of ovarian bursal lymphatic stomata in guinea pigThe surface of ovarian bursal inner layer was covered by a single layer of flattened mesothelial cell in embryonic day 60 and post natal day 1. In post natal day 15, cubical mesothelial cells were clustered in the inner surface of ovarian bursa. Lymphatic stomatas were found in the cubical mesothelial cell areas in post natal day 30. The average area of the ovarian bursal stomata was 3.363 ± 1.281 u m2 in post natal day 30, 17.384 + 2.082 u m2 in post natal day 60 , and 40.407±27.207 u m2 in adults.Conclusions The ovarian bursal lymphatic drainage unit plays an important role in active absorption from the bursal cavity. Both absorption and the opening area of lymphatic stomata in ovarian bursa could be regulated by steroid hormones in mice, which may relate to the expression levels of estrogen receptor in the nuclei of mesothelial cells. The area of lymphatic stomata on different stages were become gradully larger as mouse grows. This implied that the lymphatic stomata of the ovarian bursa may have an important reproductive function in guinea pig and mice.