fredmanning
Tourist
I dont think you are appreciating the hydrological aspect of the situation.That study is just showing pressure measurements when using a catheter. There are some congenial defects of the cervix that can increase pressure inside the uterus as a result of it being unable to “expel” normal fluids. The paper actually makes my point: pressure from the uterus out or the vagina in isn’t relevant. Again, pressure has nothing to do with it. Imagine a balloon that is tied at the end. Squeeze the balloon, the knot isn’t going to give (though enough pressure will cause damage to the rest of the balloon). Put pressure on the knot, still not going to give though you could damage the knot. Erase volume and pressure from your mind and instead imagine a vast adventure of canine sperm traveling through a huge superhighway of pitch black caverns. Imagine a human standing inside the Grand Canyon if it was 10-100x larger. That is the journey of sperm.
We have 2 chambers a) vagina b) uterus and 1 conduit - the cervix.
We have the dog knot distend the the vagina and increase pressure there. We then introduce a fluid into the vagina.
It makes perfect sense that the fluid will move under pressure into the uterus via the cervix.