BIOLOGY
OF
3, 82-92
REPRODIJCTION
A
(1970)
Developmental
W.
C.
Concept
BERGIN,2
H.
of
T.
Equine
GIER,#{176} G.
B.
Cryptorchism1
MARION,4AND
J. R. COFFMAN5
Kansas
State
University,
Manhattan,
Received
Fifty
lar
equine
fetuses
The
descent.
lish
the
By
and
suspended
to the
Expansion
from
groin
of the
by
the
vaginal
fluids
results
nal
ring.
Enlargement
canal,
inguinal
of
and
the
The
An
of the
testis
understanding
of
scrotal
palpations,
of
of
Cryptorchism,
after
canal,
not
provides
cryptorchism.
position
of
preceding
the
testis
normal
testic-
chid
animals
are
sterile,
Nes,
1966).
Cryptorchism
1 Contribution
cine,
No.
Dept.
of
tural
and
of
Department
address,
Dept.
3500
Oak
Science,
Surgery
and
No.
Kansas
State
Illinois,
and
of
Poultry
Animal
Present
Carbondale,
of Surgery
and
Midwest
fllinois
Medicine,
City,
present
Oklahoma
normally
pressure
the
inter-
stretches
between
lags
in
penand is
ligament.
to
ligament
as
the
the
days
300
much
as
6
abdominal
cm
cavity
the
be
and
diagnosed
in
the
surgical
by
inguinal
82
and
ring
testes,
and
development
of adhesions
the testis and adjacent
vaginal
1967;
(1953),
and
Frank
that
the gubernaculum
moving
force but may
able
traction
scent.
Gier
process
man
and
in guiding
and
structures, or
process
(Cour-Palais,
Nalbandov,
1964).
Marion
the
1970)
Grossman,
were
attained
in-
in its
de-
analyzed
descent
in dog, bull,
that
under
normal
abdominal
pressure
the gubernaculum
testis.
relationships
system
have
(1964)
testis
(1969,
of testicular
and
showed
1966;
Sisson
probably
is
exert consider-
provides
translates
the
the
of the equine
male
been well established
1953)
but
have
cated
from piecemeal
observations
polations
from observations
on
address,
73110.
cor-
rectal
scrotum.
Grossman
relationships
62901.
it.
to
diagnosis
deferens
(Sisson
University
present
vas
force to the
Anatomical
reproductive
University,
Science,
Industries,
testis
for
conditions,
force
and
66502.
96740.
Kansas
the
may
into
the
and
743
Agricul-
Kansas
Medicine.
basis
dicated
not the
Medi-
and
and
the
and
cells
attributed
Surgery
drawing
retroperitoneally
a
abnormal
Federman,
66502.
Dept.
Grove,
of
been
continuous
locked
to abnormal
continue
to
levels
(Eik-
Manhattan,
of Dairy
Head,
of Southern
Poultry
Biology,
Kansas
Leydig
Biology,
of
Hawaii
of
Manhattan,
Dept.
Station,
Halvaloa,
the
has
Division
2 Department
Division
50
No.
1044
Dairy
Experiment
address:
but
changes
and
at reduced
be
between
1943). Bilaterally cryptor-
show
no regressive
produce
testosterone
of
frequently
to
Cryptorchism
ular descent,
is most
frequent
in swine
and
horses,
although
it occurs
in many mammalian
species (Williams,
(epididymal)
epididymal
testis
likely
by the
mesorchium
because
the canal,
estab-
brith.
inguinal
the
of
failure
left
is more
descent
considering
or
The
so
testicular
of gubernaculum
mass
birth.
the
through
testis
the
and
thin
gonadal
gubernaculum,
testicu-
to
horses
cryptorchism.
a broad
posterior
abnormal
is surrounded
testis
by
gubernaculum
the
and
cryptorchid
to
the
gubernaculum
of
ring
the
on
descent,
types
various
tension
normal
on
wall,
and
gubernaculum
around
observe
contributing
described,
dorsal
of
through
factors
66502
1969
observations
body
after
in
internal
passes
rection
the
days
testis
to
with
the
passage
10
right
by fibrosis
in
allowing
gestation
behind
dissected
previously
process
of peritoneal
inguinal
were
correlated
processes
cavity,
connected
were
3,
November
of the developmental
importance
developmental
toneal
13 foals
findings
Kansas
how
been
those
fabri-
and interother
species
1, 2,
Figures
Fio.
I.
mesonephros
nephric
duct
process
(Insert
A x
(md),
Fic.
2.
and
progressed
and
3.
fetus,
175
with
nearly
has
the
yet
of
dissections
its
started
ligament
(PGL)
gubernacular
third
one
lateral
not
gonadal
the
outer
has
the
scrotum,
layer
been
The vaginal
days.
to
cord
(gc)
of the gubernacular
has
process
leaving
a
of the vaginal
sharply
Horse
fetus at term
The gubernacular
scrotum.
their
maximum
of the vaginal
thin,
almost
fetuses.
horse
posterior
is
fused
to
the
bulb,
enclosed
double-layered
process.
reflected as it was
vaginal
process
the mesorchium.
IC-inguinal
canal;
Sc-scrotum;
at
(TV)
The
anterior
(330
bulb,
mass
tunica
(insert C).
medially
tunic;
posterior
is continuous
of
(T)
migration,
although
posteriorly
with
gubernacular
bulb
as shown
the
the
meso-
(G).
in insert A.
The
X
2.5.
The
mesonephnic
pulled
the
duct,
into the internal
bulb
gubernacular
mesorchium
(mo
now
as shown
)between
the
epididymis
inguinal
and
(Ep)
canal.
X
in
guber-
vas
1.25. (Insert
2.5).
FIG.
with
testis
The
has enclosed
almost
(VD),
from
representations
The
days.
gone.
and
(PV)
Horse
deferens
X
diagrammatic
75
5.0).
naculum
B
3 are
fetus,
is completely
vaginal
B
and
Horse
days)
epididymal
about
250-270
(formerly
vas
deferens
X
0.7. Other
U-ureter;
testis through
tail, and
days.
vaginal
and
to the testis, and
P-pubis;
with
The
UB-uninary
testis
process)
spermatic
gland;
is connected
with
bladder;
of the
VG-vesicular
83
by
the
gland;
penis;
gland.
but
have
not
mesorchium
by penitoneal
CI-cephalic
RM-retractor
fully within
regressed
to
laterally and
are connected
wall proper,
CG-Cowpers’
PS-shaft
canal
ligament
the epididymis
(SA)
artery
to the peritoneal
abbreviations:
Pr-prostate
the inguinal
gonadal
posterior
to the
the
the
the
considerably
dorsal
vas
dorsal
wall
deferens
wall
of
the
folds directly continuous
ligament
muscle;
of
the
testis;
TA-albuginean
84
BERGIN
to the
extent
ticular
resemble
that
descent
actual
neither
descriptions
nor interpretations
events.
of
ET
AL.
of tes-
fetuses from
results
quarter
yearling
and
Most
cern
reports
clinical
Several
authors
Stanic,
1960;
on
equine
diagnosis
and
of
cryptorchism.
the
procedure
in
rection.
to
stabilize
abdomen
The
the
testis
in mammals.
Because
as a model
interpreting
the results
study
presented
are
MATERIALS
Information
was
thoroughbred,
FIG.
4.
nephroi
The
tern
Ventral
dissection
process
connects
the medial
from
FIG.
5.
Ventral
dissection
The
of metanephroi.
(UA),
gubernacular
6.
through
wall
cord
The
breed
posteriorly
55-day
horse
fetus.
and
gonadal
a
least
twice
age
in
3).
progresses
and Marion,
gonadal
in the
1970)
ridge
that
of
(Fig.
4).
the
drawings
at
about
at about
day
attained
a vol-
pig
or
bull
These
testes
oversized
from the ventral
anteriorly
by the
surface
cephalic
of the testis, dorsally by a double
of
peritoneum,
by
ligament
the
the
(M)
definitive
postero-laterally
(P)
ligament.
position,
the
The
is only
end
gubernacular
the internal
meso-
ventro-medial
the posterior
(md).
through
penis
along
connects
duct
and
gonadal
are suspended
(PGL)
mesorchium,
posterior
are nearing
testes (T)
ring. The
basic
descent
and
2,
re-
The
schematized
1,
of
to the mesonephric
junction
1969).
sexual
differentiation
55 the testes
have
same
Metanephroi
anteriorly,
to the inguinal
junction
Ventral
The
The
which
82-day
horse
was
now
removed
nearly
wall
with
inguinal
an elongation
inguinal
X
of each
cord
(gc)
ring
(IR)
of the genital
fetus,
to
was
posterior
removed
the
(ep)
which
thin
to demonstrate
and
greatly
around
enlargement
the umbilical
exposed
by
gonadal
removing
ligament,
(mo).
X
left testis rotated
(gc)
connects
enlarged
by
and
mesorchium
cord
surrounded
with
expand
only
by
vaginal
x
0.6.
skin
and
the vaginal
in the photograph
by the prepuce,
for this photograph.
(G),
a broad,
intestine
canal
greatly
surrounded
the epididymis
bulb
by
medially
prepuce
medially
the epididymal
gubernacular
the
and
2.0.
(Pr)
(G),
bulb
has
progressed
0.8.
equine
appear
slightly
of the mesonephroi
thick gubernacular
tip of the penis,
of the pubis.
rings, which
body
fetus
The
bulbs
rotated
ring. Testis, epididymis,
A short
a distinct
gubernacular
were
to the gubernacular
horse
of a 280-day
testes
(gc) is reflexed from
mesorchium.
tip of the penis, surrounded
bulbs,
cord
the dorsal
175-day
and
border
Both
as a result of degeneration
to the inguinal
through
dissection
enlarged
fetus.
ring (IR)
from
of
(ep)
to the anterior
gubernacular
scrotum,
at
the
of 36
to the base of the scrotum.
into the internal inguinal
testis.
(Figs.
testes
are suspended
of the mesonephros
shifted posteriorly
dissection
deferens
and
ume
of
1 mixed
are suspended
Ventral
extends
removed.
40.
ligament
duct-PGL
by
pat-
previously
testicular
formation
dissections
the inguinal
tail-vas
7.
normal
27 and
By day
and
postero-ventral
the epididymis
FIG.
with
detail.
posterior
canine,
a consistent
Marion,
is illustrated
day
of
distinct posterior
of
testes have
to expose
anteriorly
status
A long, thin gubernacular
the abdominal
FIG.
(G)
this series
6.0.
relationships.
artery
bulb
dissec-
photographs
from
to that
Gonadal
differentiation
horse as in the cow (Gier
major
of the mesonephros,
the mesonephric
to the gubernacular
papilla. X
A
surface
and
of
horse
the
a
degeneration
of the mesonephroi.
testis, along
which
of
are beginning
and
made
revealed
similar
(Gier
layer
from
anatomical
similar series of bovine,
dissections
of descent
of dissections
of the
horse
1
fetus
RESULTS
METHODS
obtained
13 quarter
(mes)
surface
AND
4
fetuses.
ported
entering
in some
were
and
of age, and
colt. Each
drawings,
from
for
for anatomy
and the
testicular
descent
in
of this segment
of the
here
Interpretations
human
project
to review
and reinterpret
the entire
process of sexual differentiation and testicular
the horse
basis
for
mammals,
as needed.
and
process
via the inguinal
approach.
present
study
was part
of
descent
to staged
rectal
described
to
subjected
measurements,
the findings
cor-
vaginal
prior
cryptorchid
and
a surgical
the
foal was
days
horse
tions with
cryptor-
(1964)
of
quarter
9 thoroughbred
2 to 42
found
diagnosing
al.
location
to term,
foals from
1964;
rings
(1965)
described
et
and
inguinal
for
and
Bishop
dissection
discredit
Adams
reliable
horses
Frank,
1960)
internal
con-
corrections.
1961;
Wright,
palpation
chism
surgical
(Arthur,
diagnosing
the
cryptorchism
45 days
horse
portions
process.
of
The
as distinct constrictions
has moved
process,
anteriorly
extend
almost
about
the
body
ventral
testes are pulled
between
wall
tightly
gubernaculum
to the umbilical
half their length
into
cord.
the
EQUINE
CRYPTORCHISM
85
86
BERGIN
Branches
and
vein
of the posterior
pass
through
vascularize
the
testis.
mesonephric
artery
the mesorchium
to
The
mesonephric
duct
ET
AL.
accompanying
cremaster
muscle
larized by the external spermatic
vein
which
are branches
extends
along
the
ventral
surface
of the
mesonephros,
posteriorly
to the anterodorsal
border of the pelvic urethra, suspended
from
pudendal
artery and
duct
remains
intact
the dorsal
body wall
and
urethra
by a
urethra.
gubernaculum
nects
(Gier
the
to
(Figs.
1, 4).
1A) evaginates
peritoneal
tral
which
vaginal
after
the
region
around
the
pubis
an internal
the gubernacular
process
closure
inguinal
cord
5 to
ring,
to the
45
By
150
through
The
10 days
separating
pelvic
region,
mesor-
shift posteriorly concurrent with
of metanephroi,
elongation
of the
and
extension
of
the vaginal
Each
gubernaculum
yond
the posterior
through
the lumen
extends
end of the vaginal
of the process
inguinal canal to the epididymal
from
be-
process
and
the
junction with
the posterior gonadal ligament and thence
the caudal
end of the testis.
The gubernacular
cord is suspended
from
the dorsal body
and
and
short
the
and
mesorchium
to
toneum
now
enter
10 mm
invein
persist and are now properly designated as
spermatic
vessels. The vaginal process and
the
ventrolateral
The
spermatic
with
wide
(3-mm)
the
40-45
and
gonadal
the
ligament.
long,
on
with
from
(Fig.
The
bulb,
the
6)
of
scrotal
the
about
of
posterior
process
has
length
of
the
completely
surrounding
scrotal
folds,
ameter.
The
and
equine
tip of the
by fibrous threads
rudiments
which
are
and
only
of the testis through
3 mm
a short
gubernac-
and
vaginal
is connected
canal is impossible
is
the
the internal inguinal ring
two-thirds
about
base
the
the
vein
of the vessels
its anterior one-half (Fig. 2B). The
to
of
and
midway
ends
mm
tail
gubernacular
enter
pen-
border
cord
epididymal
extended
the
artery
distal
gubernacular
the
to
ligof
plexus) reflected anteriorly. The
has increased to approximately
ular bulb, through
to
connects
the testis about
(pampiniform
gubernaculum
the
wall
along
expanded.
Passage
external
oblique
muscles.
mesonephric
artery
has become
gonadal
border
between
differentiating
ligament
A thin cephalic
the anteroventral
by a peritoneal fold continuous
with the
mesorchium.
The gubernacular
bulb is an enlarging
mass
deep
within
the
pubic
region
the
epididymal-vas
the metanephros.
ament
constitutes
gubernaculum
ternal
abdominal
The posterior
the
of the testis
border
of
from
process.
2)
thin sheet
from the dorsal
border
to the body wall and posterolateral
mesorchium,
a broader
(Fig.
taut, pulling the testes to within 1015 mm
of the internal
inguinal
ring and thus
stretching the mesorchium,
which is a loose,
metanephros.
by
days
posterior gonadal
about
55 days
and are only remnants
at 65
days
(Figs.
1, 5). The
testes
are thus
suspended
from the dorsal
body wall, rather
than
the mesonephros
closer
and
peritoneal cavity from extraembryonic
coelom.
The
mesonephroi
begin
deterioration
at
chium, and
enlargement
as the testes are drawn
inguinal rings.
the ureter and umbilical artery (Fig. 6). The
is suspended.
is first visible
of the umbilical
the
relatively
ven-
the guberthe bulb,
ring
to
remains
(Fig.
of the
at about
bulb
of
around
posteroventral
deferens connection to gubernaculum
has been
drawn
to,
if not within, the internal inguinal
ring,
thus
reflecting
the vas deferens around
and
gubernaculum
into the
progressing
forming
lateral
testis,
condition
gubernaculum,
of
and
the
the
This
mesonephric
dorsolateral
and
ventral
of
of
the internal
stable
from about
70 days to about
120 days,
with only proportional
increases
in testes
and
ligament
blastema
surface
from
vein. The
along
the
con-
the posterior end
the
of the
days,
extending
naculum
and
thus
1970)
A slitlike
vaginal
process
from the posterior
end
cavity
borders
mesonephros
fold.
A firm
Marion
from
into
lateral
the
gonadal
duct
mesonephros
slightly
and
posterior
mesonephric
the
between
peritoneal
are vascuartery and
may
slightly
the inguinal
at this time, as the canal
the
fetal
testis
30
testes,
mm
which
in
di-
are
EQUINE
extremely
large
other
animals
be drastically
The
weight
of an
g at
150
g at
300
days
150
days
be deflected
50
fetal
g at
from
the
is
loosely
testis
wall
and
medially
epididymal
the
to 1.5 cm in diameter
ular bulb
is about
except
at
surrounded
by
its
tip,
posterior
the
junction
of the
ior
gonadal
ligament
bernacular
is
cord.
a
vaginal
and
epididymal
by
The
caudal
tail
and
pole
of the
occupying
mass
expanding the inguinal ring.
The caudal
pole of the right
ically
presented
to the internal
gu-
postthus
is typby the
gubernaculum-epididymis-gonadal
complex
within
vaginal
thus
stretches
process
on
on the
abdominal
through
en-
ring
and
fluid
of the
the process, thus
the
gubernaculum.
testis
obviously
is apviscera,
which
may
the inguinal
canal.
Several
cases
and
size of
tail mass
the internal inguinal ring (Fig.
in which one or both testes were
is stretched
posteriorly
gubernaculum,
a 2- to 2.5-cm
3-
to
by
entering
the
soft cylinder,
3.5-cm
duction
passage
ovoid
testis
in
tension
inguinal
rather
the
on
the
canal
than
as
the
Re-
abdomen.
in testicular mass prior to inguinal
leaves
the testis somewhat
flaccid, al-
lowing for greater distortion of shape. Within
the inguinal canal (Fig. 9) the testis may
as
much
in
diameter,
as
10
in
prepassage
cm
long
elongation
tension
on
the
and
contrast
testis.
to
When
of the testis
emerges
(Fig.
8), pressure
complete
inguinal
ring to near the diminishing
the testis.
The enlarging
epididymal
the
help in the total movement,
but fluid pressure
is the main activating force for moving
the
on somewhat
later.
Inguinal passage normally begins between
270 and 300 days of gestation, after enlargeligament
tension
pressure
by the
tinuing
of
mass
through
force by elongating
maintaining
end of the ninth
month,
and the left testis
reaches the inguinal ring about the same time
ment
post-testicular
testis
canal. Continued
pressure
from peritoneal
into the vaginal process provides most
the
testis
ring
the
entering the internal rings (Fig. 7) or within
the canals
(Figs.
8, 9). Typically
the testis
testis
the pelvic
inlet.
The
increases
progressively,
of the
passage
to
the inguinal
canal,
while
the testes
freely within the penitoneal cavity, fre-
quently
testicular
ables
were observed
poster-
heavy
of
in
process
connected
a short,
of the internal inguinal ring by
enlargement
testis
7). The gubernaclong and 3 cm
from
the internal
inguinal
ring
3 cm with the vas deferens,
epididygonadal
ligament
typically
drawn
separated
by about
mis,
and
within
swing
(Fig.
6 cm
mass
and vaginal process were much
than
those on the right
(Figs.
7, 9).
Expansion
Some
plied
is about
inguinal
tail
gubernaculum
less developed
moving
and
cavity.
ring
by
may
attachment
ring
equine
fetus
the internal
is expanded
30
that
gubernaculan
pelvic
and
During
The testis of a 250-day
5 cm in diameter,
and
diameter,
of
testis
days,
body
inguinal
into
250
the
dorsal
the
fetal
1969).
life,
the
internal
posteriorly
those
equine
(Killian,
from
the
with
average
days,
of
suspended
comparison
(Gier and Marion,
1969),
must
reduced
in size before
passage.
is 20
at
in
87
CRYPTORCHISM
as
little
as
the
6 X
3 cm
the
posterior
from the inguinal
canal
from
the canal
and conof vaginal
process
gubernaculum,
passage
of
can have little
effect
of the testis
emerges
the
maintains
resulting
testis
in
through
the
organs
after
the posterior
from
the external
guinal
ring.
The fine fibrous strands connecting
vide
gubernaculum
some
sort
7) until it offers littleresistance to the passage
of the testis
as abdominal
pressure
is maintained
on the testis
and within
the vaginal
vaginal
process.
Less than half of the fetuses
examined
had equal development
on both sides (Fig. 8).
In three of the five 10-month fetuses, the left
vide some
any
growth
process
tension
to
the
of directional
but
on them
of body
of
pole
canal. Direct pressure from abdominal
of the
be
2 cm
and
there
at any
scrotum
for
indication
time.
gubernaculum
of the force that moves
across
the abdominal
construed to provide
the tip
may
guidance
is no
pole
in-
pro-
the
of
Differential
may
pro-
the testis
cavity
but cannot
be
any of the tension that
88
BERGIN
[_1
ET
AL.
EQUINE
pulls
only
fibrous that the testis cannot be forced through
from either direction.
the testis
through
the inguinal
ring. The
detectable source of tension on the
gubernaculum
ternal
after
inguinal
the
ring
testis
reaches
is derived
the
from
89
CRYPTORCHISM
in-
In 32 fetuses between
and
continued
birth, descent
elongation of the vaginal process toward the
scrotum, stretching the gubernaculum
until the
farther
tension
descended
the
all
is adequate
inguinal
others
to
ring. The
examined
pull
the
enormous
size (about 30 X
while
in
yet
creases
Leydig
the
testis
through
horse testis differs
in that
it attains
60 mm
abdominal
then
de-
the vaginal
process
testis
regains
in a
few weeks
the firm consistency
ical of mammalian
testes.
The earliest
complete
descent
was
found
in a 315-day
which
scrotum
soft
entiated
masses
as
that could
testes
or
the
the internal
proximately
FIG.
testes
the
8.
has
dissection
penetrated
the
dorsally
Ventral
contract
to
and become
a
ring
10-month
by
canal.
the
of
apso
13
foals
and
foals
under
testes
had
complete
left
78%
equally
left
testis
Of the
2-week-old
right
testis
testis
in
in
the
only
fills
foal
skin
the
testis
by
skin
and
the
and
freely
in
the
the
left
and
gonad
a
2-cm
epididymal
tail
removed
to
expose
tightly
and
the
process
and
out
gubernaculum.
x
fascia
from
removed
of
had
by
the
fascia
Both
abdominal
connected
to
with
one
other
canal
was
vaginal
slips
in
The
one
testis
canal.
inguinal
had
and
inguinal
the
com-
three
descended
a
Five
showed
right
while
was
age.
canal,
the
the
ligament
(G)
the
with
of
abdomen.
latter
posteriorly
inguinal
foals,
the
of
of age
than
one
descent,
within
epididymal
fetus
I week
less
old,
6 weeks
completely
the
9 were
was
descent
testis
gubernac-
2 weeks
the
the
canals,
contents.
examined,
within
in-
cases,
inguinal
surrounding
one
12
com) had
equi-
external
two
scrotal
testicular
were
the
last
the
2 were
old,
with
and
the
and
the
only
age,
fetus
horse
the
of
gubernaculum
At this period,
mesorchium
near-term
the
both
of
equine
The
(EIR).
inguinal
dissection
life,
In
processes
were
testes
without
neonatal
or
the right
testis
in the
testis
in the inguinal
testes
within
the ab-
occupied
bilateral
the
not be differ-
of
of
inguinal
restrained
9.
weeks
2
inguinal
rings
cm in diameter
external
testis
FIG.
1
Ventral
and
cavity,
first
vaginal
plete
to that
of the
gubernaculums
25,
were
1(3%).
internal
had
left
both
tails
of the
dissection.
During
cavity.
month
through
testis
was
the
dominal
1 week
prior to dissection revealed a pair of
ovoid
in
and
in only
between
ulums
testes
in the canal in a position comparable
of the right testis
in Fig. 9. Palpation
left
testes
(18%),
rings.
Two
and
the
and 2 had
Of
completely
the left
6
guinal
scrotum
canal,
and
fetus. In a 305-day
fetus
the right
testis
was
the inguinal
canal,
while
the
right
advanced
epididymal
is typ-
of both
and
in
more
distant
This weight loss leaves the testis with the
original tunic as a loose covering which is
readily
compressed
to pass through
the narcanal.
Within
tunic)
the
than
left
of gestation
right testis was
fetuses
collected
at term,
5 (42%)
had
pletely
descended
testes,
and 3 (257
both
testes
within
the inguinal
canals
to about
30 g, mainly
by loss of
cells, shortly
before
inguinal
passage.
row inguinal
(now
vaginal
7),
was
from
an
and 50 g)
cavity,
advanced
(Fig.
9 months
of the
of
the
the
tip
of
peritoneal
0.5.
the
left
side
to
expose external inguinal ring and testis, but on the right side (left side of the
picture)
the
abdominal
wall
was removed
to expose the internal inguinal ring (IR), tip of the testis, and vas deferens. The left testis was
delayed
FIG.
in descent,
10.
Testis
inguinal
ring. The
inguinal
canal,
process
FIG.
which
11.
The
comparable
and
testis was
and
reached
the
to those
vaginal
process
mostly
posterior
but
did
of the younger
of the
within
gonadal
not
right testis of a term
the albuginean
tunic is the same
the abdominal
ligament,
fill the scrotum.
fetus with
the relative position of the tunic contents.
as it was
fetus in Fig. 8. X
fetus shown
The
cavity
epididymal
x
from
the
although
the posterior
tail, and
gubernaculum
body
end
wall
was
at the
within
filled the
the
vaginal
0.62.
the vaginal
tunic incised along
testis has slipped
before
0.5.
in Fig. 8, separated
inguinal
through
passage.
the posterior
the inguinal
x
0.6.
margin
canal, not behind
to show
it, and
90
BERGIN
which occupied
the
nal
canal.
Bilateral
complete
in
the
proximal
half of the inguitesticular
descent
was
month-old
foal,
cephalic
end of the left testis
tion with the external
inguinal
tum
of the 6-week-old
foal
gubernaculums
within
the
although
the
was in apposiring. The scrocontained
only
vaginal
processes.
tained
a vas
testis
was
deferens.
At
necropsy,
descended
abdominally
the
while
with
the
located
epididymal
epididymal
was 31 cm
guinal
rings
tail,
while
the left vas deferens
long. Although
both
internal
inwere approximately
2 cm in di-
ameter,
left
was
fibrotic,
precluding
panietal
of
Any
reflexed
ited
to the
sheath
only
the
epididymal
Thus,
the
concept
deand
com-
patible
with
the conditions
encountered
by
surgeons
attempting
to correct
cryptorchism
or to castrate
(Adams,
1965).
The fetal testis
located
strictly
naculum
and
stantial
masses
the
mass
of
originates
the
days,
(1969),
man
through
of
the
as
around
50
retropenitoneally.
epididymal
an
fibrous
as
(1953)
the
by
midterm
as
described.
forces
defined
by
rived
inguinal
Gier
ring
and
Marion
be-
vaginal
tunic.
vaginal
tunic
abdominal
mesonephros,
is
from
it.
by
after
a
the
pressure
into
process
the
bernacular
tivation
vides
testis
passes
process,
inguinal
canal,
cause
pro-
in
which
a
vaginal
gubernacular
bulb.
The
and
vaginal
along
the
the
gu-
necessary
mo-
gubernaculum
in
between
10-fold
more
region,
size
55
increase
continuing
by
the
however,
of
the
cavity.
closes,
the
groin
increase
bulb
a
stretching
system
the
the
is
and
thus
pulling
posteriorly.
10-fold
another
retroposition,
peritoneal
providing
force
of
anlage
canal
around
into
testis
A
thus
the
gubernacular
to
residue
progressively,
bulb,
posteriorly
the
differentiation
around
enlarges
the
gubernac-
in
umbilical
herniates
of
the
metanephric
peritoneal
increases
process
gonadal
border
pelvic
derees-
gubernaculum,
into
closed
as
posterior
from
The
cord
descent,
were
with
the
other
(1970)
The
enlargement,
Shortly
epithe-
postpenitoneal
ventrally
mesonephric
its visceral
ventral
after
and
What has
tunic
is
pressure,
derived
cord
and
testicular
is continuous
which
horse
1969).
vaginal
Marion
the
cord
in
and
study.
viding
with
involved
Gier
along
enclosure
and
in
in this
ular
and
and
a visceral
tunic
from
Gross-
Sisson
and
45
which
connection
Marion,
visceral
ligament,
the
penitoneum
is lim-
gubernaculum,
tail
tablished
process
between
The
sub-
approaching
of
cord
guberare
vaginal
evagination
described
at
tissue,
The
gubernacular
not
The
ligament
testis.
by a
being
1953).
tunic
broad
of
albuginean
hum.
The
gubernacular
pattern
is suspended
from the dorsal
body wall
broad, thin mesorchium,
rather than
the
development
different
Sisson
and Grossman
(1953)
by Netter
(1961)
but more
of
vaginal
the
fetal
pressed
by
the
of
Dissection
of a series of equine
fetuses
revealed
a pattern
of testicular
descent
basically
accepted
of
vaginalis
of Sisson and Grosswith the processes
peritoneal,
widely
Grossman,
the
entirely
(tunica
vaginalis
propnia
man, 1953)
is incompatible
separates
the
(tunica
and
a short,
tween
ulum,
DISCUSSION
scribed
illustrated
as
Finally,
and
tunic
Sisson
part
canal.
directly
vaginal
communis
nephrogenic
passage.
from
becomes
truly
left
in the inguinal
canal.
The right vas deferwas 53 cm long from the urethra
to the
ring
the
to the
process
right
the
tail
ens
the
retroperitoneally
mammals
(Gier and
been
known
as the
was
testicular
not
vaginal
ring
con-
The
left inguinal
rectal
palpation
and
completely
AL.
remains
Both testes
and epididymides
were within
the
abdomen.
A yearling
quarter
horse colt was presented
for euthanasia
because
of multiple
limb fractures.
Clinical
examination
revealed
left unilateral
cryptorchism.
was examined
by
ET
pressure
of
the
and
before
continues
from
days
and
days
pro-
300
resistance
vaginal
gubernac-
180
to
process.
complete
The
to
abdominal
vaginal
expand
fluid
beand
EQUINE
thus
maintains
tension
cord.
After
the
internal
inguinal
mass
enlarges
to
near
the
inguinal
canal,
to elongate
in the
step
testis
of
odd that
reduction
the
ence, reduction
This
study
in
the
into
total
procedure
the
remaining
most
on the vabeing
pulled
allowing
further
in the
obvious
vathe
epididymis
deferens,
inguinal
undue
stretch
of the gubernacular
cord,
abdominal
pressure
inadequate
for proper
(3) inademass,
re-
sulting
in failure
to expand
the inguinal
and (4) displacement
of testis into the
ring,
pelvic
cavity
where
it is held
by organ
pressure,
resulting
in ineffective
gubernacular
tension.
The testes
of the horse
are so disproportionately
large
cult,
and
that
descent
any
is particularly
abnormality
cryptorchism
in 55.8%
amined,
with bilateral
son (1963)
observed
involved
right
testis
on the left
were
left
An
role
must
await
are distinct
gestation.
Presumably,
of androgen
by
is in the
horses
tions
presented
are
also
clusions
1.
of the
noticeably
between
corresponding
of placental
there
is a high
days
mass,
days’
to the time of
gonadotropins.
150
this
of
high
If
with
may be
the testis
situation,
the
vas
surgical
correction.
are seen in cryptorchid
for surgery.
All three
condiobserved
in developmental,
and
may
adult
anatomy.
Several
3.
con-
be drawn.
Digital
palpation
of the scrotum
between
250 days and term gestation
may be deceptive,
as the gubernaculums
large and have
the feel and
are quite
texture
of
of testes.
the first
persist
life.
The
That
condition
may
3 weeks
of neonatal
continues
truly
scends,
produc-
50 and
In
simplify
situations
testes
2.
descent
testicular
after
250
vas
frequently
yond the first month
of life,
the gubernaculum
decreases
testis
is real and
cryptorchism.
in testicular
palpation,
abdomen.
may
three
explanation
the retardation
in treating
The
(3) The epididymis
inguinal
canal
while
pation
All
of the
left
by rectal
testis and
deferens
will pass through
the internal
inguinal
ring. Diagnosis
of this condition
by rectal
pal-
farther
than
that
32 fetuses
which
of the
deferens
internal
be intra-abdominal.
rectal
some difficulty;
located
in the
further
clarification.
Leydig
cells
at 45 days and constitute
a conproportion
diminish
gestation,
production
Descent
descent
of testosterone
siderable
but they
tion
was reported
117 cases
ex-
anatomical
in the
was not found,
but
must
be considered
of
testis.
had progressed
in 78%
of the
examined.
The
in
vas
the
therefore,
will not pass through
the
canal.
This condition
may be deter-
mined
retention
in 7%. Johnthat
over
50%
of the
the
for retardation
diffiresult
may
as-
in the horse.
Surgical
basic
situations:
(1)
epididymis
may be lo-
and may be palpable
(2) The
retained
adolescent,
cryptorchism.
Left
unilateral
by Stanic
(1960)
cases
may
it is
production.
the clinical
in the inguinal
canal.
The
therefore,
pass
through
include
(1)
expansion
of the vaginal
process,
quate
growth
of the post-testicular
cated
will,
descent,
of testosterone
applies
well to
inguinal
ring
examination;
cavity.
testicular
inguinal
passage
occurs
after
drastic
of testicular
tissue
and,
by infer-
pects
of cryptorchism
findings
include
three
The retained
testis and
abdom-
failures
activates
the
inal
(2)
The
diameter
fluid
pressure
in the testis
of any
results
testosterone
gubernacular
is decreasing
about
40%
inguinal
canal
thus
in-
creased,
continued
ginal process
results
scrotum.
Failure
the
testis
is pulled
against
ring, the entire
post-testicular
testis, while the testis
in mass.
With
the
through
the
ginal
process
on
91
CRYPTORCHISM
the
size of
while
the
to increase.
cryptorchid
due
to
a
testis
failure
to
never
de-
enter
the
internal
inguinal
ring
prior
near or shortly
after birth.
to
The
over
predominance
unilateral
plained
of
cryptorchism
by the relatively
of descent
of
testis,
coupled
for
Be-
left
closure
may
be
slower
right
exrate
the left epididymis
and
with
consistent
internal
92
BERGIN
inguinal
pre4.
ring
and
closure
postnatal
Diagnosis
of
tinely
lower
include
inguinal
ination
of
in
immediately
should
rou-
palpation
and rectal
internal
of the
exam-
inguinal
ring
and the pelvic
region.
Rectal
palpation
of a vas deferens
in the internal
inguinal
ring
may
the epididymis
If the testis
5.
be
be
forced
ternal
inguinal
therefore,
reserved
back
ring
the flank
for cases
torchid
testis
abdomen
deceptive
if
has passed
the
is in the inguinal
cannot
by
through
without
been
rectal
it
in-
the
The
tify
surgeon
should
the structures
tain
that
didymal
leaving
he
has
examine
removed
not
tail and
the testis
and idento be cer-
removed
the
gubernaculum
in the abdomen.
epiwhile
pp.
267-270.
opment.”
H.
Suppl.
nosis
R.
(1965).
and
Amer.
castration
Ass.
G.
ARTHUR,
torchid.
Equine
H.
Vet.
W.
BERGIN,
An
Pract.
GIER,
H.
of
the
T.,
73,
(1967).
eds.)
equine
and
Bissiop,
Some
Vet.
University,
for
horizons
determination
fetuses. Master’s
J.,
AND
on
cryptorchidism
76,
1041-1048.
AND
MARION,
of
Thesis, Kansas
“Abnormal
Sexual
Saunders,
G.
7th
Devel-
Philadelphia.
B.
(1969).
Development
genital ducts. Biol.
testes and
Ed.
Minnesota.
Repro.
testis.
L. Van
1, pp.
gery,”
pp.
E.
thesis,
horses.
State
J.
V.
Am.
J.
Vol.
mit,
New
the
Mod.
Prenatal
(1961).
M.
3.
horse
York.
and
SurPubli-
visceral growth.
M.S.
Manhattan.
Castration
10,
of
cryptorchid
451-462.
“Reproductive
Physiology,”
San
Francisco.
“Reproductive
System,”
2nd
Products,
Sum-
26.
p.
J.
GROSSMAN,
Animals,”
D.
(1953).
4th
Ed.,
“Anatomy
pp.
585-586.
Philadelphia.
N.
Vet.
WRIGHT,
Press, New
Pharmaceutical
Domestic
Saunders,
D.
Gomes,
Veterinary
Freeman,
2. Ciba
AND
A.
R.
American
Med.
Jersey.
S.,
N.
Medicine
(1915).
Vet.
F. H.
Ed.
and
University,
pp. 44-45.
Ed.
Development
Testis”
“Equine
A. V. (1964).
NALBANDOV,
“The
Illinois.
(1969).
Kansas
LACROIX,
(1970).
In
1-45. Academic
710-711.
J.
B.
Demark,
(1963).
Wheaton,
G.
G.
MARION,
(1960).
Proc.
G.
with
41,
Castration
of
cryptorchids.
30-33.
(1960).
Laparo-orchidectomy
abdominal
in
Vet.
cryptorchidism.
the
Rec.
42, 57.
DAVID,
Rec.
and
Manhattan.
observations
M.,
cryp-
44, 629-633.
Surgery.”
Minneapolis,
(1967).
26-35.
Vol.
STANIC,
age
D.
N.
L.
of
385.
Developmental
useful
State
of the equine
Burgess,
AND
JoHNsON,
SissoN,
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