Vie CONG. I{TERN. REPROD. ANIM. INSEM. ARTIF.,, PARIS, 1968, VOL. II

FERTILIZING ABILITY AND BIOLOGICAL
ASPECTS OF SPERM STORAGE IN VITRO

T. NIWA
Department of Animal Science, Faculty of Agriculture
Iwate University, Morioka, Japan.

The survival of sperm in vitro - its life continuance as a
unicellular entity - is a very interesting biological problem.
It is also very important in the practice of artificial insemina -
tion with respect to preserving fertilizing ability for as long as
possible.

Under present conditions it is difficult to obtain any exact
evaluation of the fertilizing ability of sperm by microscopic,
histological and physico-chemical examination without using
conception trials, so we usually estimate it by measuring
sperm motility. Unfortunately results do not always agree.

At this stage it is pertinent to examine the results of
studies on the changes that occur during the in vitro storage
of sperm. Work on the relationship between metabolism and
motility during storage has confirmed that the energy which
is required for the survival of the sperm is obtained through
respiration and fructolysis.

1) As is general in the case of animal tissue, metabolism
of the sperm occurs under aerobic conditions, i.e. respiration
works through the TCA cycle, in conjunction with the oxidative
phosphorylation system. Phospholipids, particularly lecithin,
were considered the main substrate for endogenous respiration,
but the latest studies make it clear that plasmalogen is of
greatest importance.

Many diverse substances from outside the cell participate
in the process of exogenous respiration: sugars, glycerol,
lactic acid, pyruvic acid, and some types of fatty acids and
amino acids.

As factors influencing aerobic metabolism, we can cite
the following: temperature, pH, osmotic pressure, ions, light,
x-rays, dilution, the addition of some sorts of diluents and
antibacterial agents, gases and vibration, etc. The rela-
tionship of sperm metabolism to ATP, phosphagen and deep-

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