In this study
Sexualleben des wassermanns method for evaluating phenotypic sex in Nile tilapia was validated. A technique uses aceto-carmine squash mounts to stain the entire gonadal tissue for microscopic examination Method 2- squash Sexualleben des wassermanns was compared with a technique based on traditional histology. Approximately Nile tilapia fry weighing and measuring, respectively, between 0.
In situ microscopic examination on the gonads was also performed. A reliable sexing using squash mount was possible with fish weighing more than 0. Male Sexualleben des wassermanns tissue was characterized by the presence of cysts containing spermatogonia and spermatocytes, while females were easily identified by the presence of oocytes at the perinucleolar stage.
The technique proved to be efficient Sexualleben des wassermanns only in terms of sex proportion in fish but also because it allows immediate evaluation of gonadal
Sexualleben des wassermanns and demands less time and labour.
The Nile tilapia Oreochromis niloticus
Sexualleben des wassermanns one of the fish species most cultured around the world. The primary reasons that make the species suitable for aquaculture are resistance to diseases and tolerance to a wide range of environmental parameters, besides white meat with no internal spines.
On the hand, one of the main problems in culturing Nile tilapia is its precocious sexual maturity, which can be reached when Sexualleben des wassermanns weigh g months after hatching.
The efficiency of this method on several factors size and age of Sexualleben des wassermanns fish, amount and type of hormone, period of administration, etc SHELTON et al. Typically, grow-out fish farmers buy sex-reversed Nile Sexualleben des wassermanns fry, presumed to be all-male, when they are days old, weighing no more than 2g. However, in many cases after months reproduction will start Sexualleben des wassermanns fish will not grow to full market size.
This protocol may serve as a tool either to speed up access to results in masculinization studies or to be used by fish producers to check the percentage of males when buying fry for stocking in grow-out ponds.
Approximately fry, from
Sexualleben des wassermanns to 60 days after hatch were sexed. Fish weight and length varied according to Sexualleben des wassermanns from 0. The in situ macroscopic Method 1 and squash mounted microscopic Method 2 observations were compared and Method 2 was Sexualleben des wassermanns histologically.
For microscopic examination Method 1 fish were cut ventrally, using a scalpel, from the genital papilla to the base of the pectoral fin. A window on the lateral side was opened and the viscera were removed, leaving gonads, swim bladder and kidneys in place.
Once the pair of gonads was identified, a macroscopic observation based on the morphology, location, and insertion of the Sexualleben des wassermanns tissue was made. Then, a few drops of Bouin's solution were applied topically to the gonads.
This procedure hardened the gonadal tissue facilitating its removal. After macroscopic examination the anterior and posterior ligaments were cut, and both gonads were removed using a forceps and placed on a glass slide. After the solution was filtered, using filter paper and transferred to a dark bottle. Aceto-carmine solution added and the tissue covered with a cover slip.
Both gonads were then examined over their entire length under a compound microscope using magnifications of x and x Method 2. The gonads of 40 fish examined using methods 1 and 2, weighing between 0. Once the viscera had been removed and the gonads Sexualleben des wassermanns it was possible to make a macroscopic distinction between male and female gonads. The
Sexualleben des wassermanns of fish weighing 0.
Subsequent removal hampered by tissue fragility, and microscopic observation on squash mounts was also difficult due to lack of cell differentiation. Reliable distinction between the sexes was possible with fish heavier than 0. The morphology of the gonads and their location and insertion in the abdominal cavity were useful observations for Sexualleben des wassermanns the gonadal sex using Method 1.
Male gonads were thin, translucent and located ventrally to the swim bladder, extending caudally from the to the genital papilla. Figures 1A and 1C show testicular tissue under a dissecting microscopic at different magnifications. Figures 1B and 1D demonstrate the same Sexualleben des wassermanns after the addition of Bouin's solution. When Bouin's interacted with the testicular Sexualleben des
Sexualleben des wassermanns it conferred firmness and integrity facilitating identification and removal of the gonads.
Without prior addition of Bouin's male gonads were very difficult
Sexualleben des wassermanns remove due to their fragility, and tendency to form a tight coil once detached. After removing the gonads from the abdominal cavity and placing Sexualleben des wassermanns on a glass slide we observed that the testes readily absorbed the stain solution and when in contact with it rolled up, despite prior Bouin's Female gonads were thick opaque, had a shape, and were also located on the Sexualleben des wassermanns side of the swim bladder.
However, the anterior part of the ovary
Sexualleben des wassermanns located more caudally than the testis and it was possible to identify the ligaments that held the tissue to the body wall Figures 1E1F1G and 1H. The ovarian tissue showed less affinity to the stain solution and in contrast to testicular tissue did not roll up when in contact with it.
To validate Method 2 for Nile tilapia we observed the gonads of the same fish 40 in total under Method 2 and traditional histology. Figures Sexualleben des wassermanns2C and 2E show the gonads of 3 fish sexed by Method 2, while Figures 2B2D and 2F show the same tissue submitted to histological analysis. Under Method 2 the gonadal tissue was defined as testis by the presence of cysts.
Sometimes it was possible to identify the developmental stage of cells inside the cysts. Through histology, it was possible to define the stage of the cells on the testis, aalthough the cysts limits could not clearly be.
On the other hand, in the ovaries it was possible to identify the same kind of structures by the two techniques Method 2: Figures 3A3C and 3E ; histology: Oocytes at the perinucleolar stage were observed.
However the nucleoli were more clearly Sexualleben des wassermanns through histology. The of the Sexualleben des wassermanns sex of the 40 fish examined under Method 2 was confirmed by the histological examination. When sexing fishes with the squash method were used the following criteria to define male and female gonadal tissue: At a magnification of x Figure 4A it was not possible to define the cell structure of the testis, although the cysts could
Sexualleben des wassermanns easily seen.
the other hand, Sexualleben des wassermanns this magnification it waaaas observed oocytes at the perinucleolar stage inside the ovaries Figure 4B. A magnification of x Figure 4C and 4D allowed a better definition of what was seen at x. At the Sexualleben des wassermanns of x the cysts inside the testis were well defined and spermatogonia and spermatocytes could clearly be observed Figure 4E.
In the ovaries at x it was further confirmed the observations at and x Figure 4F. The macroscopic technique Method 1 proved to be an adequate auxiliary technique for sexing Nile tilapia above 0.
However, it does not allow defining differences between sexes based on cellular structures, which may cause some misinterpretation when just macroscopic sexing is used. The validation of the squash technique Method 2 through
Sexualleben des wassermanns demonstrated that Nile tilapia
Sexualleben des wassermanns above 0.
Sexualleben des wassermanns technique developed for staining chromosomes in squash of plant materials has also been used for sexing Nile tilapia GALE et al. Furthermore the stained gonads were sexed Method 2 under a compound microscope with the use of magnifications ranging from x to x.
Since both gonads were removed intact from the abdominal cavity, it was possible to observe the gonads longitudinally in both sexes, and if further investigation was necessary it was possible to proceed to histological analysis.
The squash technique also allows the identification of intersex individuals in Nile tilapia, mainly by the presence of oocytes scattered among testicular tissue AFONSO et al. Reliable sexing, where morphological and cellular distinctions between sexes, could be made was possible fish heavier than 0.
summary, the method described for sexing Nile tilapia staining the gonadal tissue and examining it microscopically proved to be effective. Furthermore, the method allows for a fast analysis of sex proportion and also demands less material, labour and time than histological procedures. This technique be used either as a tool for determining the sex ratio in sex control studies or by producers for checking Sexualleben des wassermanns success of the sex reversal process.
Schifino-Wittmann, as well as the staff of Pathos Laboratory. We also would like to thank Dr. Donaldson and Smith for the scientific revision of Sexualleben des wassermanns manuscript.
Metodo para incubacao artificial de ovos de tilapia Sexualleben des wassermanns Oreochromis niloticus. Revista da Sociedade Brasileira de ZootecniaBrasil, v. Sex reversal in Nile tilapia Oreochromis niloticus using a nonsteroidal aromatase inhibitor.
Journal of Experimental ZoologyNew York, v. Hormone and sex Sexualleben des wassermanns in fish emphasis on salmon.
Asian Fisheries SocietyManila, v. of Nile tilapia Oreochromis niloticus by immersion in androgens. AquacultureAmsterdam, v. An aceto-carmine squash technique for sexing juvenile fishes. The Progressive Fish-Culturistv.
Hormonal induction Sexualleben des wassermanns sex reversal in fish. Factors affecting androgens sex reversal of tilapia aurea. Feminization of Oreochromis mossambicus by the administration of Diethylstilbestrol. Masculinization of Oreochromis mossambicus by administration of 17 a -methylandrosten-3 b -diol through rearing Sexualleben des wassermanns. Current ScienceColumbus, v.
Progressive Fish-Culturistv. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Services on Demand Journal. RESULTS Once the viscera had been removed and the gonads exposed it was possible to make a macroscopic distinction between male and female gonads.
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