Oviduct

Definition

A duct or tubular passage that conveys eggs from the ovary toward the exterior or into a reproductive chamber; in arthropods, typically formed from modified mesodermal or ectodermal tissue and often divided into regions such as the calyx, common oviduct, and lateral oviducts. In insects, paired lateral oviducts usually unite into a median or common oviduct that opens at the ovipore; in arachnids, the oviduct may be short and muscular, leading to a uterus or brood chamber. The term distinguishes egg-conducting tissue from the vagina or bursa copulatrix where present.

Etymology

From Latin 'ovi-' (egg) + 'ductus' (leading, conduit).

Example

In grasshoppers (Caelifera), each ovary drains via a lateral oviduct into a common oviduct that terminates at the genital chamber; muscular contractions of the oviduct wall propel eggs toward the ovipositor during oviposition.

Synonyms

• egg duct
• ovarian duct

Related Terms

• ovary
• ovipositor
• spermatheca
• bursa copulatrix
• vagina
• uterus
• genital chamber
• lateral oviduct
• common oviduct
• calyx

Usage Notes

In vertebrate zoology the term often refers specifically to the fallopian tube, but in entomology and arachnology it applies to any egg-conducting passage regardless of embryological origin. Some authors reserve 'oviduct' for the mesodermal portion and 'vagina' for the ectodermal portion, though usage varies; 'common oviduct' versus 'lateral oviduct' specifies position relative to the ovarian pair. The term is not used for sperm ducts (see vas deferens).