Äggledare

Äggledare, or oviduct, is the tubular passage that connects the ovary to the uterus or the exterior in animals that lay eggs. It serves as the main conduit for the ovulated egg and, in many species, the site where egg components such as albumen, membranes and shell are added before the egg is laid or before implantation of a fertilized egg.

Anatomy and function vary across taxa, but most vertebrates share a sequence of regions. In many birds and reptiles the oviduct includes an infundibulum that captures the ovulated egg, a magnum where the albumen is added, an isthmus where membranes form, and a shell gland or uterus where the shell itself is produced. The final passage usually occurs through the cloaca. In mammals, the oviduct (fallopian tube) is shorter and specialized for fertilization and early embryonic development, guiding the ovum from the ovary toward the uterus.

Reproduction and egg development rely on the oviduct’s proper function. In birds, the length and activity of the oviduct influence egg quality, including shell strength and albumen thickness. In humans and other mammals, obstructions, infections (salpingitis), or tubal dysfunction can lead to infertility, and ectopic pregnancies can occur when embryos implant in the oviduct.

Etymology and usage: the Swedish term äggledare translates to the oviduct, encompassing both mammalian fallopian tubes and the avian/reptilian egg-conducting ducts. See also oviduct, fallopian tube.