A study of the factors controlling embryo transport in the oviduct of the mouse.
The time course of tubal transport through the oviduct of the mouse has been examined in some detail. It comprises a multi-factorial system, consisting of ciliary activity, fluid elaboration and muscular contractility, alterations in which may adversely affect fertility. This study has examined this process fron a variety of viewpoints. The results indicate that a volume of fluid passes from the oviduct between Days 1 and 2 of pregnancy, the time at which embryos normally pass into the isthmus, but the role of this fluid is uncertain. Administration of oestradiol by injection into one bursa ovarica produces effects which are more pronounced than SC administration and are laterally biased. An in vitro system has been developed in which embryo transport occurs from Day 2 and Day 3 onward for up to 16 hours, but does not occur fron Day 1 onward. Isthmic transport in vitro can be manipulated pharmacologically, and the presence of alpha-adrenergic receptors is suggested. The musculature is proposed as the most important factor in isthmic transport. Removal of ovaries and adrenal glands resulted in a retardation of tubal transport which can be reversed by progesterone administration and measurement of serum progesterone levels indicates that progestogenic activity is required for normal tubal transport. Administration of testosterone also caused delay which could be reversed by progesterone administration which confirms that continued progesterone activity throughout the tubal transport phase is required. The role of progesterone is discussed, but further work on tubal progesterone and oestradiol receptor levels and their interactions are required for a definitive result.
Fertility, Embryo, Tubal transport, Oviduct, Isthmic transport, Muscular contractility, Progesterone, Oestradiol
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