Veterinary Archives, Vol. 74 No. 2, 2004.
Original scientific paper
Annual oscillation of ovarian morphology in European pilchard (Sardina pilchardus Walbaum) in the northern Adriatic Sea.
Srebrenka Nejedli
; Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Zdravko Petrinec
; Departmant of Biology and Pathology of Fish and Bees, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Snježana Kužir
; Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Emil Srebočan
; Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Zagreb, Croatia
Abstract
Annual oscillation of ovarian morphology in European pilchards (Sardina pilchardus Walbaum) caught in the period July 2001 to June 2002 in the region of the Northern Adriatic (Croatia) was studied. Fifty females were taken in the middle of each month and determining body mass they were dissected, ovaries extracted and weighed, and the centre of each ovary was sampled for histological analysis. Samples were fixed in Bouin’s solution, mounted in paraffin and cut into 6 μm-thick slices which were stained with hematoxylin and eosin (HE) and using the Periodic-acid Schiff method (PAS). During oogenesis the oocytes passed through four developmental phases: peri-nucleolus stage (phase I), yolk vesicle stage (phase II), yolk stage (phase III) and mature stage (phase IV). Oocytes in phase I were present during all months, forming more than 40% of all oocytes. Their percentage increased from May to August (P<0.05) and was the highest in August (84%). Percentage of oocytes in phase IV increased from October to April (P<0.05) and was the highest in November (36.3%). An increase in percentage in phases II and III of oogenesis was noticed in September and remained at an almost equal level until May. The developmental cycle of oocytes began in September and October, coinciding with an increase in the ovarian mass, which achieved its maximum level in October, remaining at an almost equal level until April. During this period the mass of ovaries reached more than 4% of body mass, and the GSI (gonadosomatic index) was significantly different (P<0.05) from other months.
Keywords
Sardina pilchardus Walbaum; ovaries; oocyte stages; Adriatic Sea; Croatia
Hrčak ID:
67812
URI
Publication date:
22.4.2004.
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