engleski

Morphological changes in gonads of Astacus astacus during the reproductive cycle

Crayfish are gonochoric and have males and females although intersex individuals occur in low frequencies. The gonads lie dorsally in the thorax and their size and appearance depend on the age and reproduction condition of the individuals. In this study, we have examined changes in testis and ovaries of Astacus astacus during the reproductive cycle. Testis’ s were collected each month from May 2003 until January 2004 and ovaries were collected each month from May 2003 until October 2003. Gonads were weighed and then approximately half of the gonads were fixed in Bouin's fixative for 24 hours and half were dried at 80 º C for 24 hours. Wet and dry gonad weight and gonad moisture content were measured. Histological sections of testis and ovaries were stained with haematoxylin-eosin for morphology analysis, Sudan Black B for demonstration of lipids and Periodic Acid Schiff (PAS) reaction for carbohydrates. Relative gonad index of males fluctuated all year around within a very small range, i.e. between 0.2 and 1.5% while in females it gradually increased from 0.7% measured in May until 12.3% measured in October. Spermatogenesis in testis of A. astacus started in August while cogenesis started a month earlier, in July. Spermatophores were still present in vas deferens sampled in December. Changes in intensity and distribution of Sudan Black B and PAS coloration in gonads were noticed during reproductive cycle.

Astacus astacus; gonads; histology

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