Studies of Annual Gonadal Development and Gonadal Ultrastructure in Spiny-Cheek Crayfish (Orconectes Limosus)

Abstract

The aim of this study was to follow the gonadal development in freshwater crayfish Orconectes limosus (Rafinesque) by histological examination of ovaries and testes as well as monthly investigation of the gonadosomatic index over a period of one year. Male gonadosomatic index (I G ) ranged between 0.11 to 0.79% with a minimum in July (0.11%) and maximum in September (0.79%) while in females it ranged between 0.25 to 6.15% with a minimum in July (0.25%) and maximum in April (6.15%). Between April and May, the histological dissection indicated presence of mature oocytes and oocytes undergoing resorption. Egg extrusion took place in mid April. During the summer months, the volume of oocytes gradually decreased. In winter and spring, the volume of oocytes began to increase during preparation for egg extrusion. The size of oocytes in the ovary increased from 0.2 mm at the beginning of the reproductive cycle to 1.8 mm immediately before egg extrusion. Average number of eggs in the ovary was 140. 8 ± 51.63 (76-290). The ovary was of brown colour for the majority of the cycle, but white in June and July and orange in August and September. Mating started in October and continued through the winter. A difference was found in the proportions of testis and vas deferens in the male reproductive organ during the year. The male gonadosomatic index increased in September during preparation for mating (I G = 0.79%). During the mating season, the male spermatophores were predominantly filled with spermatozoa and sperm was also noted in the vas deferens. Two out of 15 males sampled during the winter were found to be intersex, in which atretic oogonia and oocytes were present at the periphery of testicular tissue and occupied less than 15% of testicular tissue. The evidence of intersex strongly suggested transitional stages of a gradual change of sex, which may be qualified as partial hermaphroditism. Key ÉTUDE DU CYCLE ANNUEL DE DÉVELOPPEMENT DES GONADES ET DE LEUR ULTRASTRUCTURE CHEZ L'ÉCREVISSE AMÉRICAINE (ORCONECTES LIMOSUS) RÉSUMÉLe cycle annuel de reproduction de l'écrevisse américaine (Orconectes limosus) a été décrit par l'observation externe des gonades, en enregistrant les changements de l'indice gonadosomatique (I G ), et par l'analyse histologique des organes reproductifs (ovaires et testicules). L'observation et l'analyse histologique ont été realisées mensuellement. Les valeurs suivantes de l'I G ont été trouvées : 0,11-0,79 % (mâle) et 0,25-6,15 % (femelle). La valeur minimale de l'I G pour les mâles a été observée au cours du mois de juillet (0,11 %) et la valeur maximale au cours du mois de septembre (0,79 %). Pour les femelles la valeur minimale a été observée en juillet (0,3 %) et la valeur maximale en avril (6,15 %). La formation d'ovocytes mâtures et leur désintégration ont été observées ou cours de la période avril-mai. L'expulsion d'ovocytes mâtures a été observée en avril. Le volume des ovocytes a augmenté principalement en été. Néanmoins les ovocytes ont commencé à grandir au cours de l'hiver et du...

Distribution and biometry of native and alien crayfish in Trentino (Italian Alps)

“…On the contrary, in our study the sex ratio of O. limosus populations was unbalanced towards males, as reported in other studies on this species Pilotto et al, 2008). The male-biased sex ratio notwithstanding, O. limosus abundance appeared to increase quickly in all the monitored populations, probably due to the fast growth rate, high fertility, and early sexual maturity reported for this species (Kozák et al, 2007;Souty-Grosset et al, 2006).…”

Morphological and histochemical examination of male and female gonads in Homarus gammarus (L. 1758)

“…The droplets that are seen in H. gammarus for the first time in the vitellogenic oocytes, do not stain with Bromophenol blue and Alcian blue and produce a PAS negative reaction. This is indicative of lipid-like characteristics, as seen in A. leptodactylus [23,[31][32][33]. Kulkarni et al [34] do not mention lipid droplets in their definition of vitellogenesis in P. clarkii.…”

“…The mature oocytes store yolk intensely and are ready for spawning in H. gammarus, as in other taxa. At this stage, the mature oocytes of H. gammarus have a smaller size compared with those of Virilastacus araucanius [35], Orconectes limosus [33], C. quadricarinatus [25,30,36], P. clarkii [21] and A. leptodactylus [23]. The yolk granules are abundant in the periphery of the mature oocytes, closest to the cell membrane.…”

Different aspects of reproduction strategies in crayfish: A review

“…Also, histology reveals both spermatocytes and oocytes. Among the cambarids, Kozák et al (2007) reported that during the mating season of O. limosus the male spermatophores were predominantly filled with spermatozoa and sperm was also noted in the vas deferens. However, two out of 15 males sampled during the winter were found to be intersex, in which atretic oogonia and oocytes were present at the periphery of testicular tissue and occupied less than 15% of testicular tissue.…”