HISTOLOGICAL ANALYSIS OF THE ANNUAL CYCLE OF GONAD DEVELOPMENT IN THE MALE SPINY-CHEEK CRAYFISH ORCONECTES LIMOSUS RAF.
Łucjan Chybowski*, Dorota Juchno**
*The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
** University of Warmia and Mazury in Olsztyn, Poland
ABSTRACT. Histological analyses were conducted of the annual cycle of male gonads of spiny-cheek crayfish Orconectes limosus Raf. Although changes in the male gonads throughout the year are clearly evident, they are not uniform in all males. Spiny-cheek crayfish mate mainly in the autumn from September to November. After mating, the gonads of male crayfish can be divided into two groups according to their histological structure. In the first group there is an abundance of sperm in the gonads, while the testicular tubules in the second group are either empty or contain a small amount of sperm. This division remains until May. In May, the histological picture of the gonads is uniform, and there are either very few or no tubules containing sperm. In June O. limosus males occur in two forms. The histological pictures of first- and second-form male gonads do not differ. However, beginning in July and also in August and September, the gonads of first- and second-form males do differ. First-form male crayfish gonads contain more sperm than those of second-form males. From October onwards, all of the males are first-form, and primarily spermatids and sperm are visible in the gonads. The possibility that the spiny-cheek crayfish mates twice annually, once in autumn and again in spring, is discussed based on changes observed in the histological picture of the gonads.
Key words: SPINY-CHEEK CRAYFISH (ORCONECTES LIMOSUS), MATING, REPRODUCTION, SPERMATOGENESIS
Łucjan Chybowski, Instytut Rybactwa Śródlądowego, Zakład Rybactwa Jeziorowego, ul. Rajska 2, 11-500 Giżycko; Tel./Fax: (87) 428 38 81; e-mail: email@example.com