Validation
of an ovarian biopsy method in a sea bass, Centropomus medius Günther
Abstract:
In the present study, the establishment and
validation of an ovarian biopsy method for in vivo assessment of
oocyte maturation in the snook, Centropomus medius Günther, is
described. Diameter and morphological characteristics of intra-ovarian
oocytes siphoned with a polyethylene cannula were analysed fresh, preserved
with 1% formalin in 0.7% NaCl solution and also cleared with Serra solution.
There were no effects detected of the preservative solution on the opaque
oocytes within the 24-h interval of the test. The clearing solution allowed
excellent visibility of the membrane thickness, yolk appearance and germinal
vesicle. Oocytes from each of the five ovarian sites of all examined females
were in different prematuration stages and those on the tertiary yolk
globule stage had a unimodal diameter frequency distribution and their
diameter means were not significantly different among sites (P > 0.01)
on eight females. In vivo and in vitro samples of the eight
females examined were not significantly different (P > 0.05).
As samples obtained with the polyethylene cannula are representative of the
ovary central portion, an estimate of the coefficient of variation corrected
for bias (P < 0.05) for 20 means of repeated in vivo
samples was 1.4 ± 0.47. The results obtained demonstrate that for
the species studied, the biopsy method is satisfactory, providing
representative samples of the ovaries with the required precision.
(Institute
of Aquaculture, University of Stirling, Stirling FK9 4LA, UK. E-mail of D.G.
Tortolero,: d.a.guerrero-tortolero@stir.ac.uk)