A histo-morphological characteristics of gonads in Mudskipper, Periophthalmus waltoni Koumans, 1941 from Helleh estuary, Southwestern Iran

In this study, the morphological and histological studies of male and female gonads in mudskipper, Periophthalmus waltoni Koumans, 1941 from Helleh estuary (Bushehr Province, southwestern Iran) were performed to determine its gonadal development stages and histo-morphological characteristics. Sampling was done from April 2010 to March 2011 and a total of 81 individuals were collected by hand net. The gonads of specimens were removed, their sexes determined and then fixed in 10% formalin solution after checking their morphology and measuring their weights, lengths and widths. Six stages of gonadal development in females and four stages in males were determined based on macroscopic and microscopic observations and reproductive indices. In female, increasing of the ovary size is occurred because of the accumulation of yolk materials in oocytes, and in the last stages, little folding in ovary was observed. Formation of zona radiata and yolk granules in the third stage, and increasing thickness of this layer and yolk granules were observed from stage three to stage six. In male, gradual developments of the sperm cells were observed from stage one onward.