Observations on Reproductive Organs and Tissues of Two Freshwater Cyprinid Fishes

Two freshwater fish models were selected caught in river Tigris passing through Neinava province, to investigate their reproductive systems. A total of 45 of Hemri Barbus luteus and 32 of Ethri, Varicorhinuus trutta were examined during the period between January 2008 and November 2009 to study their female and male reproductive systems, from gross morphological and histological aspects .Females shown to possess a pair of elongated ovaries situated at the ventral side of the swim bladder, connected with it and other viscera by thin mesenteries. It revealed from histological studies that ovaries are coated with tunica albuginea, from which folds are protruded towards the cavity of the ovary known as oogerous lamella .Six main stages were distinguished in oogenesis, these are: 1. oogonia. 2. chromatin-nucleolus. 3. perinucleolar stage which is further divided into: pre-perinuclear stage, early peri-nuclear stage, later perinuclear stage.4. Yolk vesicles stage. 5. Yolk granules stage. 6. Ripe egg stage.The diameter of the mature ovum is: 1161.8 μm in Hemri, while in Ethri is (1215.9) μm. In these ova, yolk vesicles appeared with blue color in Mallary triple stain while yolk granules are red in color with the same stain. In addition atretic oocytes were observed in the final stage of atresia as the vesicular cells absorb the yolk, and the cytoplasm of oocytes and remaining tissue converted into corpus luteum. Males of Hemri and Ethri posses one pair of testes, which are white in color, elongated and their ventral side in Hemri possesses a ventral groove, these testes are situated in ventral side of the swim bladder and are connected with and other viscera by thin mesenteries. The testes are coated by a layer of dense connected tissue which possesses elastic fibers and blood vessels, the thickness of this layer differ by different maturation stages, inner to this layer is a testes stroma which consists of interstitial connective tissue, seminiverous tubules which are separated by fibrous partitions extended from tunica albuginea. Six stages were distinguished in the spermatogensis, these are: 1. Primary spermatogonia. 2. Secondary spermatogonia. 3. Primary spermatocytes. 4. Secondary spermatocytes. 5. Spermatids. 6. Spermatozoa.