Cranial stumps of premature oviducts redeveloped into fully differentiated oviducts in laying hens
In birds that are kept as pets, hysterectomy is a therapy for abnormal laying activity. The aim of this study was to investigate whether hysterectomy is a possibility to stop egg production in laying hens as well. A total of 36 hens were hysterectomized, 18 of them in the 12th week of age, 18 in the 14th week of age. The hysterectomy was performed as follows: An incision with a length of about 1.5 cm was made at the left side of the hen, between the last rib and the vertebral column. The oviduct was grasped with forceps and, after preventing hemorrhage via ligatures, cut at the cranial and caudal end and taken out. The incision was sealed with single stitches. In some cases, a small cranial stump of the oviduct, less than 1 cm in length, was left in the hen to avoid ruptures. After the surgery, all hens were examined daily via ultrasonography daily to see whether there were any follicles in the abdomen. In the 22nd week of age we found calcified eggs in the ultrasound of some of the hysterectomized hens. We decided to terminate the study and euthanized all hens. In the following dissection we saw that all laying hens in which a cranial stump of the oviduct had been left possessed a fully differentiated, newly developed oviduct. Only the connection to the cloaca was missing. We assume that the cranial part of a premature oviduct is able to develop into each cell type in laying hens, including uterus cells with the ability to form egg shells.