Original scientific paper
https://doi.org/10.1515/aiht-2016-67-2730
Occurrence of intersex in wild freshwater fish in Slovenian rivers: a histological evaluation
Milka Vrecl
; Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia
Vlasta Jenčič
; Institute of Pathology, Wild Animals, Fish and Bees, Veterinary Faculty, University of Ljubljana, Ljubljana, Slovenia
Abstract
The aim of this preliminary research was to establish if there are intersex occurrences in wild freshwater fish in Slovenian rivers and streams. In the first study we evaluated all fish species of both sexes obtained from the river Ljubljanica from its source to mouth. In the second study we focused on the rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta m. fario) males from 30 rivers and streams in different parts of Slovenia. The male gonads were histologically assessed for the presence of oocytes to determine the frequency and degree of intersex. Oocytes were found in the testicular tissue of a single grayling (Thymallus thymallus) and in the adipose tissue adjacent to the testis of a single common barbell (Barbus barbus), both from the Ljubljanica. Several cyst-like structures that resemble degenerated presumptive oocytes were also present in several trout testes. This preliminary report is the first of its kind in Slovenia. To gain a better insight into the intersex issue in Slovenia, we plan to regularly biomonitor freshwater pollution by histologically examining fish gonads and, if possible, by determining vitellogenin plasma levels in fish.
Keywords
gonads; histology; intersex; oocytes; wild freshwater fish
Hrčak ID:
166318
URI
Publication date:
22.9.2016.
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