Microscopic Analysis of Mustelus schmitti´s Uteri During Reproductive Cycle

Aims: It was analysed with light and electron microscopy the different zones of the Mustelus schmitti`suteri along the reproductive cycle.
Study Design: Histological routine techniques were used.
Place and Duration of Study: Specimens of Mustelus schmitti were collected from the Bahia Blanca estuary, each month, from 2002 to 2006. They were caught by longlines. The fishing was made at the top of the tide during the day.
Methologogy: A total of 24 animals were collected and processed; 11 were immature, 6 were maturing and 7 mature females; 4 of this last group were pregnant. Each animal was humanely sacrificed. A longitudinal ventral incision was made in each animal so as to remove the reproductive organs. The pieces were stored in Bouin solution for light microscopy and in 2.5% glutaraldehyde in 0.1 M cacodylate with 12% saccarose for transmission.
Results: In immature animals, the simple columnar epithelium shows small and numerous folds, PAS (-) and AB (-). Beneath this epithelium, muscular fibers in longitudinal disposition alternate with connective tissue, finishing in a simple serosa.
The uterine epithelium of the anterior portion in mature females, between the isthmus and the cervix, is stratified, PAS (+) and AB (+). Three muscle layers continue and the first one displays a disposition like a net. The second layer has longitudinal fibers divided into two by vascularized connective tissue and the third, is very thin. A typical serosa encloses the organ. In the posterior portion of the uterus in mature females, the epithelium is also stratified but with more secretive cells.
The presence of sperm was detected in the cervix and in the posterior portion of the uterus suggesting a special uterine epithelial-sperm interaction.
Conclusion: The uteri suffer a cyclic remodelation not only in the epithelia but in the muscle layers.