Oocyte Transport: From Ovulation to Implantation

The journey of the oocyte (egg) from ovary to uterus takes ~3–4 days and involves coordinated tubal mechanisms:

1. Ovulation: LH surge → follicular rupture → oocyte + cumulus cells released into peritoneal cavity.
2. Pickup: Fimbriae (ciliated fringe of fallopian tube) sweep oocyte into tube. Ciliary beating + smooth muscle peristalsis create current.
3. Transport to ampulla: Fertilization typically occurs here (outer 1/3 of tube) within 12–24 hrs post-ovulation.
4. Zygote transit: Cilia and peristalsis move dividing embryo (cleavage stages) toward uterus.
5. Morula → blastocyst (Day 3–4): Enters uterine cavity via uterotubal junction.
6. Implantation (Day 6–7 post-fertilization): Blastocyst hatches, attaches to receptive endometrium, invades.

Disruptors: PID (tubal scarring), endometriosis, prior ectopic, tubal surgery, smoking (impairs ciliary function), IUD (alters tubal environment). These increase ectopic pregnancy risk and infertility.

IVF bypasses tubal transport entirely.