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Anatomy of Dogfish

One of my peers in classed posed a very good question in my comparative anatomy class and my professor, being human, did not know the answer. In females, how do the eggs get from the ovary to the ostium in the midventral portion of the falciform ligament? I bleive the egg starts in the ovary and develops in the ostium and gets fertilized somewhere in-between but I am not sure how. I havenít lost sleep over it but I thought I ask again anyway because my scientific curiosity has gotten the best out of me. Do you know? You biophilic friend P.S. Upon my honor, this wasnít homework question.

Wildlife Expert - Ken Burton

I'm glad to know that the finer points of Chondrichthyian urogenital systems aren't keeping you awake at night.

In sharks in general (the dogfish being a typical shark), the eggs develop in the ovaries, usually only in one ovary. They then are discharged and pass first through the ostia into the oviducts, then through shell glands where sperm are stored and fertilization occurs before moving on through the oviducts to the uteri, where the embryos develop. The ostia fuse in the falciform ligament, which attaches the liver to the abdominal wall and is not directly involved in reproduction. The ostia are merely the openings to the oviducts; no development occurs there. In sharks they are enlarged to accommodate large eggs. How exactly do the eggs get from the ovary to the ostia? I guess they ask directions.

Sweet dreams.

Additional information on the web:
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species:

Spiny Dogfish
Squalus acanthias


Smooth Dogfish
Mustelus canis

   
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