is for this reason impossible to observe it in 90% of the spermatozoa
(serie 1, fig. 2).

In longer storage there appears a second deviation of the acrosome, A
dark coloured area is showing up at the proximal part of the acrosome,
of which an exact description is not possible, It looks like the acro-
some has settled itself somewhat looser on the spermatozoa head and
is shriveling in that position (fig. 3).

10 days later this phenomenon may be observed with more than 60% of
the spermatozoa, after a fortnight with 95%, whilst 35 - 50% of the
spermatozoa are still living at that time.

Influence of cold shock on the acrosome

Quite another effect can be observed by submitting the spermatozoa to
cold shock. Depending on the C.S.'s force, some changes in the acro-
some occur which eventually are causing a complete bareness of the
spermatozoa. The whole process can be summarized in 5 stadia
(series 2, fig. 4 up to 8).

After the loss of the apical border area, vesiculation of the acrosome
appears at the proximal part caused by a slight C.S. (fig. 4). During a
vehementer C.,S. this may lead to a complete vesiculation of the acro-
some (fig. 5). The acrosome may then move its position (fig. 6) till it
has pushed itself off the head (fig. 7)., Finally during the most vehe-
ment and prolonged C,S., it appears that the aequatorial plate may
turn loose, thus only a p.n.c. showing itself at the head (fig. 8).
According to table 1, the frequency of appearance of the different sta-
dia is strongly dependent on the temperature stretch covered by the
C.S. Obviously the temperature of 15 C is a very critical one. Sudden
drops in temperature to 15°C have only a very slight influence, whilst
the same temperature interval below 15 C has a much more drastic
outcome, The vehementer the C,S., the larger is the percentage of
irreversible immobile spermatozoa.

Discussion

In literature controversially opinions are expressed towards form and
structure of the acrosome (13), Mostly it is assumed that the acrosome
is composed of 2 parts, i.e. an "inner'" and an ''outer' acrosome. The
posterior border of the former is supposed to be straight and adjoining
to the p.n,c., whilst the latter crescently shaped. In this case it is re-
marquable that only the second shape is visible with light microscopi-
cal research and that the first shape has never been observed. With
electronical microscopical research (14) however a distinct straight
border of the acrosome at the p.n.c, is to be observed. The changes
of the acrosome of the living spermatozoa during storage in vitro were
not followed by post-mortem changes. The observations made by Han-
cock (11) during which he observed vesicular acrosome deviations, are
based on the fact that he kept the spermatozoa in storage at 0 C before
fixation and observation. Bedford's supposition (7) that the loss of the
acrosome, found at rabbit spermatozoa in the female reproductive
tract is caused by a senility of the spermatozoa, has not been confirmed

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