1063-0740/05/3102- © 2005 Pleiades Publishing, Inc.
Russian Journal of Marine Biology, Vol. 31, No. 2, 2005, pp. 115–118.
Original Russian Text Copyright © 2005 by Biologiya Morya, Neznanova, Ivankov, Reunov.
The degeneration of residual gametes that takes
place in the gonads and is the ﬁnal stage of the gonadal
cycle is one of the regulatory factors providing the
beginning of the subsequent stage of gametogenesis
[8, 9, 24]. Gaining an understanding of the molecular
and ultrastructural essentials of the postspawning
degeneration of gametes is one of the urgent problems
set by the biologists that work out recommendations for
regulation of gametogenesis in cultivated species of
Metazoa [33, 34].
It is known that in bony ﬁshes the beginning of a
new cycle of gametogenesis in the gonad is anticipated
by intensive phagocytic activity in follicular cells
resorbing residual spermatozoa in the cytoplasm [2, 3,
10, 15–19, 22, 23, 26–28, 31]. According to our prelim-
inary results [5, 7], in some members of Teleostei the
degeneration of residual gametes can also take place via
cell disintegration, i.e., a process typical of some Meta-
zoa [6, 8, 9], but never reported for bony ﬁshes. As we
have discovered the degeneration of residual male
gametes in bony ﬁshes as well, further studies on this
process are needed to expand our knowledge about the
postspawning destruction of gametes in this group of
In this paper we discuss the mode of destruction of
residual spermatozoa in the pointhead ﬂounder
, as a ﬁsh species with cyclic func-
tioning of the gonads, and the chum salmon
, as an example of an anadromous ﬁsh, where
the postspawning degeneration of residual gametes is
followed with death of the cells of the entire body. In
our studies, we used TEM techniques.
MATERIALS AND METHODS
For our studies we collected three specimens of the
pointhead ﬂounder (Ussuriiskii Bay, Sea of Japan,
August 2001) and three chum salmon specimens (the
mouth of the Kievka River, October 2001). All sampled
ﬁsh were males at the stage V of maturity. The stage of
maturity was determined by visual characteristics .
The sampled ﬁsh were dissected alive. Pieces of
gonads were ﬁxed with 2.5% glutaraldehyde prepared
on 0.1 M cacodylate buffer (pH = 7.4) and postﬁxed
with 2% solution of osmium tetroxide prepared using
the same buffer. After dehydration in a series of alcohol
of ascending concentrations and acetone, the material
was embedded into an Epon–Araldite mixture. Thin
sections were made with a Reichert-E ultratome. The
sections were then stained with uranil acetate and lead
citrate and examined and photographed in a JEM-100B
transmission electron microscope.
RESULTS AND DISCUSSION
The studies of the chum salmon
and pointhead ﬂounder
Postspawning Destruction of Male Gametes
in Polycyclic and Monocyclic Bony Fishes: Pointhead Flounder,
Schmidt (Pleuronectidae) and Chum
S. Yu. Neznanova
, V. N. Ivankov
, and A. A. Reunov
Far East State University,
Vladivostok 690600, Russia
Institute of Marine Biology, Far East Division, Russian Academy of Sciences,
Vladivostok, 690041 Russia
Received June 11, 2004
—The process of the destruction of nonreleased spermatozoa was studied using TEM in the
postspawning gonads of the chum salmon
and the pointhead ﬂounder
, as representatives of monocyclic and polycyclic ﬁshes respectively. It was shown that in both species
residual sperm cells are destroyed through fragmentation of chromatin and the entire cell. It is supposed that
the process of destruction in this case is connected with autolytic disintegration known in some multicellular
animals, but never described for Teleostei.
bony ﬁshes, destruction of spermatozoa.