World Journal of Fish and Marine Sciences 4 (2): 159-164, 2012 ISSN 2078-4589 © IDOSI Publications, 2012 DOI: 10.5829/idosi.wjfms.2012.04.02.56406 Corresponding Author: Solmaz Shirali, Department of Basic Sciences, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Iran. Tel: +98-9166113587. 159 Histological Studies of Common Carp Ovarian Development During Breeding Season in Khouzestan Province, Iran Solmaz Shirali, Naeem Erfani Majd, Mehrzad Mesbah and Masoud Reza Seifi 1 1 2 3 Department of Basic Sciences, Faculty of Veterinary Medicine, 1 Shahid Chamran University of Ahvaz, Iran Department of Clinical Sciences, Faculty of Veterinary Medicine, 2 Shahid Chamran University of Ahvaz, Iran Department of Pathobiology, Faculty of Veterinary Medicine, 3 Shahid Chamran University of Ahvaz, Iran Abstract: Ovaries of 49 common carp brooders were collected during April to October 2010. Tissue samples were taken from anterior, median and posterior portions of the ovaries. Thin sections were prepared and stained by H&E and PAS. Histological examination showed that breeding seasons in common carp in this area take long at least 7 months and spawning were continued since April to October. It seems that previtellogenesis and vitellogenesis stages are short in Khouzestan climate condition and this species enter in maturation phase rapidly. Histological and histometrical results showed that the minimum and maximum diameters of follicles were observed in chromatin nucleolus and secondary vitellogenic follicles respectively. Zona radiata reached to maximum thickness in secondary vitellogenic follicles. Nucleus reached to maximum diameter in primary vitellogenic follicles. There was significant difference in parenchyma percentage between three stages of reproductive cycle. Also, the gonadosomatic index (GSI) from previtellogenesis to vitellogenesis and maturation stages was increased significantly (p<0.05). Key words: Ovarian development %Histological studies %Spawning %Common carp INTRODUCTION under short photoperiod had low GSIs and their ovaries Common carp is one of the most important fish females exposed to the long photoperiod had high GSIs species in aquaculture [1-3]. Ovarian structure of and ovaries with vitellogenic oocytes. Khouzestan cyprinidae family has changes in the annual reproductive province located in the southwest of Iran with long cycle [4, 5]. The most suitable method of determining the photoperiod and high temperature and is a major centre reproductive cycle in female fishes is to observe seasonal for the culture and export of freshwater fish [11], but only developmental changes in the gonads [5]. It is well known limited information is available on reproductive biology that photoperiod and temperature has profound effects of common carp in Khouzestan province. The aim of on reproductive performance of fishes [1, 6, 7]. this survey was determination of common carp ovarian Quintana et al. [8] showed that high environmental status and structure in breeding season and in climate temperature is enough to trigger sexual maturity in fish condition of Khouzestan province, Iran. from temperate climate. Bapary and Fainuulelei [9] showed that photoperiod and temperature are involved MATERIALS AND METHODS in the regulation of gonadal development and a long photoperiod within a suitable range of water temperatures Seven mature female common carp were obtained is required for continuity of reproductive activities. in each month (April to October), the mean length was Miranda et al. [10] reported that female fishes that kept (68.16±1.13cm) and mean weight was (5.57±0.29kg), from contained only previtellogenic oocytes, in contrast,