Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock
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Effects of eyestalk ablation on ovarian maturation of wild and pond-reared Penaeus monodon were determined to compare their reproductive potential. This was done by counting the oocyte size frequency in four regions of the ovary and comparing the percentage of each cell type present at each stage of maturation per group. Sampling of ablated prawns was done during three maturation or spawning periods within the first molt cycle after ablation. It took 5 and 14 days for wild and pondreared prawns, respectively, to show signs of ovarian maturation after ablation. Percentage of proliferating cells, the smallest germinal cells in the prawn ovary, was higher in wild unablated (8.3%) than ablated (2.5–5.0%) groups. Significant differences were observed in all cell types at different stages of maturation. In both unablated and ablated prawns, there was a uniform development of the whole ovary and similar occurrence of atresia at all stages. The presence of bigger oocytes in the ovaries of ablated prawns sampled after spawning provided histological evidence for lower number of eggs per spawn and faster rematuration.
CitationTan-Fermin, J. D. (1991). Effects of unilateral eyestalk ablation on ovarian histology and oocyte size frequency of wild and pond-reared Penaeus monodon (Fabricius) broodstock.
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ArticleWild immature Penaeus indicus females (11.5 ± 3.1 g body weight) were ablated by pinching, cautery or tying of one eyestalk, and stocked with control (unablated) females and males (9.2 ± 1.5 g) in a 12-m3 maturation tank. Full ovarian maturation and spawning were attained 4 days after ablation/stocking in all treatments, with a peak at 5–6 days. Seventy-five percent of ablated and unablated females spawned during the study period. Average egg numbers from complete spawns increased with size of females for all treatments. There was no significant difference in fecundity of complete spawns from the various treatments. However, hatch rates of unablated P. indicus were significantly higher than eyestalk-pinched females but not those ablated by cautery and tying. Similarly, survival after the 15-day period was lowest among pinched females.
Effects of unilateral eyestalk ablation on growth and reproductive parameters in wild and pond-reared Penaeus monodon (Fabricius) broodstock. JD Tan-Fermin -
The Philippine Scientist, 1991 - San Carlos Publications, University of San CarlosEffects of unilateral eyestalk ablation on wild and pond-reared Penaeus monodon during ovarian maturation were determined by examining the growth (e.g., carapace length, body length, body weight) and reproductive (e.g., gonad weight, gonadosomatic index (GSI), average and maximum oocyte diameter) parameters to compare their reproductive potential. Growth parameters were similar in the wild unablated and wild ablated prawns from the immature or previtellogenic (P) to mature or cortical rod (C) stages but increased during the immature (P) to maturing or vitellogenic (V) stages in the pond ablated prawns. During stage C, gonad weight was highest in the wild unablated group while GSI, average and maximum oocyte diameter was similar in the three groups. After spawning (stage S), gonad weight was similar in all groups but GSI, average and maximum oocyte diameter were higher in the pond ablated prawns than in the wild unablated and wild ablated groups. Changes in growth and reproductive parameters at various stages of maturation suggest that reproductive performance successively decreased in the wild unablated, wild ablated and pond ablated P. monodon.
ArticleRA Pudadera & JH Primavera -
Kalikasan, The Philippine Journal of Biology, 1981 - University of the Philippines Los BañosPrawns were subjected to the following treatments: blue light, red light, natural light, and natural light plus unilateral eyestalk ablation. Unablated prawns under blue and natural light developed stage III ovaries; under red light ovarian maturation reached only stage II. Ablation resulted in full maturation of ovaries and subsequent spawning. The external changes of the ovary were generally the same for both the ablated prawns under natural light and the unablated under different light qualities. Under blue light, however the ovary at stage III had numerous atretic cells and the diameter of its ova was more uniform. The maturation stage and mean gonadosomatic indices were high for the ablated and low for the unablated prawns.