Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. I

Differences in morphology and properties of gametes in fishes and their
importance for the elaboration of adequate methods of artificial
insemination.

ANNA S. GINSBURG
Institute of Developmental Biology, Academy of Sciences of the USSR,
M oscow, USSR.

Morphology and properties of gametes of different animals, including
fishes, as well as sperm-egg interaction at fertilization, have recently
become an object of extensive study but our knowledge in this field is
still of little use in pisciculture. The present paper reports some results
obtained when investigating gametes and fertilization in Acipenserid
and Salmonid fishes.

. BEHAVIOUR OF GAMETES IN WATER AND COELOMIC FLUID.

Fish spermatozoa are activated by water and maintain their motility
in it during a variable period of time. This period is short in Salmonids.
In the lake trout its average duration equals 125 sec. (at 9°C), while the
period of progressive movement, which ensures fertilization, lasts 40 sec.;
at the same time the fertilizing capacity of diluted milt is kept for 30 sec.
only (at 10-12,.2°C). Spermatozoa of Acipenserids remain motile in
w ater for a much longer time. Observations performed on the milt of 20
sturgeon males (at 15-18°C) showed that the period of the progressive
m ovement of a vast part of spermatozoa lasts about 3-5 min., as a rule,
w hereas some of them, so-called "longliving spermatozoa", go on
swimming during several hours. The fertilizing capacity of milt is pre-
served in different males during a variable time, from 15-20 min. to 12
hours (Fig. I).

Spermatozoa of some fishes, as trout, salmon, grayling, suspended
in coelomic fluid are fully activated and maintain motility much longer
than in water (during 10-25 min. in the lake trout). In other fishes,

e.g. whitefish and pike, spermatozoa are much less active in coelomic
fluid than in water. Finally, in many fishes such as sturgeons, Volga
herring and some Cyprinids, spermatozoa in coelomic fluid remain
immobile (1).

The activity of Salmonid spermatozoa in coelomic fluid makes it
possible for fertilization to be accomplished not only in water, but in
this medium as well. A cytological study has shown that in such eggs
the fertilizing spermatozodn enters the micropylar canal and in its termi-=
nal part comes into contact with the cortical cytoplasmic layer (2).
Sturgeon eggs, however, are not fertilized in coelomic fluid. Sturgeon
spermatozoa not only remain immobile in coelomic fluid, but their
activation is hampered in this latter medium: the percentage of ferti-
lization clearly diminished if sperm had been mixed with a small quantity
of coelomic fluid before insemination.

Eggs of different fishes as well as spermatozoa maintain fertilizability

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