The cyclic changes of the lymph vessels in the uterus of the mouse which has been pregnant.

When adapted to the natural possibility of reabsorption of the uterus, using the dye Patent Blue Violet and Japanese ink, the orthograde demonstration of the cyclical behaviour of the lymphatics during the oestrus cycle was successful even with parous mice. As investigations have already shown in nulliparous mice (5), the characteristic variations in all five stages of the sexual cycle are also found here: As a result of the pregnancies the lymphatics of the endometrium are more strongly developed, in contrast to the nulliparous mouse. However, in the stage of pre-oestrus and oestrus the marked or very marked widening, of varying calibre does not show in such a striking way. In the subsequent two stages of the secual cycle prominent elevations are found in the lumen of the uterus, and these have lymphatic capillaries running in them. The further stage, a more or less reticulate arrangement of the lymphatic capillaries, with fine branching ramifications, is equally typical. As a result of the pregnancies, the larger lymphatic vessels are often curled up like a cork-screw, and also show their typical beaded appearance.