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Microstructure of the Oviducal Gland in the Common Sawshark, Pristiophorus cirratus

Browyn Stevens, Geoff Shaw, Terence Walker and William Hamlett

University Of Melbourne, PARKVILLE, AUSTRALIA

THEME: ASFB

To determine the microstructure of the reproductive tract in the aplacental viviparous chondrichthyan, Pristiophorus cirratus, longitudinal sections of the oviducal glands of maturing and mature animals were examined by light microscopy. Developing embryos rely on yolk sequestered in yolk sacs during the initial 13 months of an 18-month gestation. During the first 6 months of gestation, each embryo is enclosed in a thin candle case, which is produced by the oviducal gland. The embryos continue for the remainder of development free in the uterus. The present study shows that the oviducal gland of P. cirratus displays the same fundamental zonation as found in other chondrichthyan species, with an anterior club zone, papillary zone, baffle zone and terminal zone. The microscopic organisation and histochemistry of these zones display similar patterns to other species. The tubule epithelium of each of the zones contains two cell types: secretory cells and ciliated cells. The secretory cells of the club and papillary zones stain periodic acid-Schiff and alcian blue positive, whereas those of the baffle zone stain negative. The terminal zone is minimal and in preovulatory animals the secretory cells stain periodic acid-Schiff and alcian blue positive; however, in gravid animals these cells stain periodic acid-Schiff and alcian blue negative. Sperm have been observed only in the baffle zone tubules of preovulatory animals. It is uncertain whether or not sperm are stored in this zone, as the terminal zone is traditionally considered to be the site of true 'sperm storage'.