CYPlA is a major inducible enzyme in the
metabolism of xenobiotic substrates. In this paper we
investigate by means of immunohistochemistry, the
tissue distribution of constitutive cytochrome P4501A
(CYPlA) during the period of endogenous nutrition
(from hatching until day 4) in developing gilthead
seabream, Sparus aurata larvae. For this purpose, a
polyclonal antiserum (BN- 1, Biosense Laboratories)
directed against conserved piscine CYPlA sequences
was used on paraffin-embedded sections from seabream
larvae. From hatching onward, CYPlA immunoreactivity
was observed in the following tissues and
cells: syncytial, oil-globule envelopes and matrix of the
yolk-sac, kidney (epithelia of renal tubules), cardiac
muscle cells, skin epidermal cells, troncal musculature,
enterocytes of different intestinal regions, goblet cells of
the bucco-pharyngeal region, gill epithelia1 cells and the
endothelia of the vascular system of various tissues
(especially from liver and brain). Moreover, eye (retina),
olfactory epithelium and some positive nerve fibers
located in the proximity of the olfactory bulbs and
running ventrally toward the posterior brain were
strongly CYPlA immunoreactive. In general, the
intensity of immunostaining increased with larval
development