freezing, etc., are also interesting problems.

2) There have been many excellent studies on the metabolism
of sperm in anaerobic conditions, particularly the reports on
fructolysis and the sugars which are used as the substrate. It
is thought that fructolysis works through the Embden-Myerhof
pathway and, from the standpoint of basic studies and practice,
we should turn our attention to the enzyme necessary for
fructolysis and the influence of CO, partial pressure on the
process.

3) With regard to the relationship between conditions of
storage and morphological changes in the sperm, we should
consider the DNA content of the cell and changes in the acro-
some, etc.

4) Evaluation of fertilizing ability of spermatozoa.

Today, it is still difficult to judge the fertilizing ability of
spermatozoa correctly, without conception trials. However,
there are some possible elements which might help evaluation.
Those are:

Motility of spermatozoa

Respiration (O, uptake)

Fructolysis

Impedance change frequency (I.C.F.)
Resistance of spermatozoa to temperature shock
Resistance of spermatozoa to special solution
Methylene -blue reduction (M.R.T.)

Percentage and forms of abnormal spermatozoa
DNA content of sperm head

Plasmalogen content

Condition of acrosome

Others

Although in recent years remarkable progress has been
made in basic biological studies of the sperm during storage,
there is a pressing need to discover methods for exact
evaluation of fertilizing ability in vitro. It is to be earnestly
hoped that someone amongst those of us who are active in this
field will be able to solve this question which seems quite com-
plex and difficult. Such success will do much to help in getting
to the kernel of the problem.

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