Reproductive anatomy of adult female emus (Dromaius novaehollandiae)

The following investigation was conducted in order to describe the morphology of the female reproductive system of an adult, two year old physically mature, but reproductively inactive female emu (Dromaius novaehollandiae). The dissections focused on the morphology of the reproductive tract of the female emu including the vasculature and the innervation of the reproductive organs.

For this investigation, five female emus (Dromaius novaehollandiae) were obtained. Three were two years old, physically mature, but reproductively inactive. These emus were anesthetized and an endoscopic exam was done and a video recorded. Two were yearlings and not physically or reproductively mature. The emus were prepared for embalming via intravascular injection of 10% formalin and submerged in a 5% formalin solution. Two days after fixation, colored latex was injected into the arteries and veins to aid in the visualization and dissection of the vasculature of the reproductive tract.

The reproductive tract of the adult female emu consisted of an ovary and oviduct situated on the left side of the abdominal cavity. The left ovary was a dark brownish-black color with the ventral surface of the ovary covered in follicles. The ovary was medial to the spleen and associated with the ventral surface of the cranial and middle lobes of the left kidney.

The left oviduct was a nearly straight tube that extended from the cranial extent of the left ilium (which corresponded to the thoracolumbar junction) to the caudal border of the left pubic bone. The oviduct was divided into five regions from cranial to caudal based on the pattern and orientation of the mucosal folds. The regions of the oviduct were the infundibulum, the magnum, the isthmus, the uterus and the vagina.

The arterial supply of the ovary and oviduct was accomplished by the ovarian artery, the cranial oviductal artery, the accessory cranial oviductal artery, the middle oviductal artery, the caudal oviductal artery and the medial and lateral vaginal arteries. These arteries supplied various regions of the oviduct and were branches of the left cranial renal artery, the left pubic artery, the left middle renal artery and the left pudendal artery.

The left ovary was drained by a single ovarian vein which joined the left adrenal vein and subsequently emptied into the left side of the caudal vena cava. The veins of the oviduct were satellites of the arteries that supplied the oviduct and also drained into the caudal vena cava.

The main innervation of the reproductive tract was via a large ovarian nerve plexus which emerged laterally from the left adrenal gland.

Overall the anatomy of the ovary and oviduct of the female emu was similar to the domestic fowl. The ovary was located on the left side of the abdomen, but the color, shape and size of the ovary and the follicles varied in the emu from that of the domestic fowl. Differences in the oviduct were observed in the pattern and orientation of the mucosal folds in the magnum, uterus and the vagina in the emu and from the domestic fowl. The pattern of vasculature was similar in both except for the presence of the accessory cranial oviductal artery, the anastomosis of the caudal oviductal artery with the dorsal uterine artery and the presence of medial and lateral vaginal arteries in the emu.