©2011 Poultry Science Association, Inc.
Observations of testicular abnormalities
in Gallus domesticus males
J. R. Moyle, S. M. Whipple, F. D. Clark, and R. K. Bramwell1
Department of Poultry Science, University of Arkansas, Fayetteville 72701
Primary Audience: Researchers, Broiler Breeder Managers
SUMMARY
While conducting research on testicular development in Gallus domesticus, it was noticed
that several of the males had nodules on their testes. On further histological investigation, we
observed that these nodules were composed of seminiferous tubules that were contained within
the tunica vaginalis of the testicular capsule. The seminiferous tubules within these nodules
contained sperm and spermatids at various stages of development; however, no direct outlet
of the sperm into the testes was identified or observed. These testicular nodules were found
in the most common primary breeder males investigated from 9 flocks, with occurrences for
individual males (n > 450) ranging from 42 to 93%. The flocks that were investigated consisted
of commercial breeder flocks, individually caged males, and males used in pen trials. Nodules
were also found in a pure line of French Mottled Houdan chickens as well as in a randombred
broiler breeder line from the 1980s. The majority of nodules were observed on a single testis,
the left testis in 90.3% and the right testis in 0.6%, with 9.032% of males with nodules on both
testes. The number of visible nodules on the testes ranged from 1 to as many as 18, with the
size ranging up to 4.5 mm. Using histological preparations, we detected these testicular abnormalities in males as young as 18 wk of age and in males that had not been light stimulated. No
conclusion about the effects of testicular nodules on fertility was apparent because all the flocks
investigated had normal or higher fertility. Therefore, the etiology and subsequent effects of
these testicular nodules in roosters are unknown.
Key words: broiler breeder, male, testis
2011 J. Appl. Poult. Res. 20:577–583
doi:10.3382/japr.2010-00244
INTRODUCTION
While measuring testicular weights and development in a flock of broiler breeder males,
we observed that the testes of some roosters
had nodules protruding from the exterior of the
testes (Figure 1). On further examination of an
additional flock, we observed that some of the
males in that flock also possessed nodules on
1
Corresponding author: [email protected]
their testes. Using histology, we observed that
the nodules were composed of seminiferous tubules that contained sperm in all stages of development. Literature searches failed to show any
information on the subject. However, similar
testicular nodules have been observed during
laparoscopies of various psittacine species (F.
D. Clark, unpublished data). The scope of this
paper is to present the data that were collected
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Figure 1. Representative example of the nodules on the testis of a 55-wk-old broiler breeder male. The number of
nodules varied from 1 to 18, and the size could range up to 4.5 mm.
from commercial flocks, to increase awareness
of these nodules among researchers and breeder
flock managers.
The avian testes are located in the body cavity of the male bird, and because of the high body
temperature of avian species, they must function at a higher temperature than testes found in
mammals. The testes are connected to the wall
of the body by a mesorchium, which also serves
as a conduit for the nerves and blood vessels
that supply nutrients and enervate the testes [1].
The testis is surrounded by 2 tunicae. The outer
tunica is the tunica vaginalis and is composed
of 2 layers. The second is the tunica albuginea,
which is located just inside the tunica vaginalis and is the fibrous capsule of the testis [2, 3].
The interior of the testis contains seminiferous
tubules, Leydig (or interstitial) cells, and connective tissue that contains the blood capillaries
[1]. The seminiferous tubules are composed of
germinal epithelial cells and Sertoli cells and are
the site of spermatogenesis. As the spermatozoa
mature, they pass from the seminiferous tubules
into the rete tubules and then on into the vasa
efferentia, the epididymis, and finally the ductus
deferens. In the domestic fowl, the ductus deferens is the site of sperm storage before ejaculation. The present investigation was undertaken
to verify the occurrence and morphological features of these nodules in flocks of poultry.
MATERIALS AND METHODS
A total of approximately 450 males from 9
commercial broiler breeder flocks in 3 different
states were evaluated in this study. All males
that were reared at the University of Arkansas
Research Farm were raised in compliance with
the provisions of the Institute Animal Care and
Use Committee, as specified by the Animal
and Plant Health Inspection Service, USDA, in
9 CFR Part 1(1–91). Males from commercial
flocks were euthanized by approved and humane
methods. Samples of males and male strains
Moyle et al.: TESTICULAR ABNORMALITIES
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Figure 2. Occurrence of testicular nodules in 7 flocks of commercial broiler breeders (flock 1, n = 60 males; flock
2, n = 66; flock 3, n = 29; flock 4, n = 30; flock 5, n = 27; flock 6, n = 44).
Figure 3. Distribution of nodules on the testes of commercial broiler breeders (n > 450).
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Figure 4. Histological preparation showing the seminiferous tubules contained in nodules on the testis of a 64-wkold broiler breeder male.
from all the major primary breeding companies
were evaluated. The majority of the commercial
males were 55 wk or older, with the oldest being
67 wk of age. One flock (flock 5) was 24.5 wk
old at the time of evaluation. Males as young as
18 wk of age were also investigated to determine
whether nodules were present before light stimulation, but they were not used in reporting the
location or rate of occurrence. Because all flocks
were evaluated on the farm, not all data were
collected from all the flocks. For example, the
data sets of some flocks may have lacked data
on testes, BW, or both. All flocks were reported
to have normal or higher fertility at the time of
evaluation. To evaluate the testes of the males,
the males were euthanized with CO2 or killed by
cervical dislocation. A minimum of 27 males per
flock were sampled, and all flocks sampled were
reported to be free of disease. After the males
were euthanized, they were weighed and the testes were removed and weighed individually. At
the time of weighing, the testes were examined
for visible testicular abnormalities, including
exterior nodules. A small sample of males were
anesthetized to verify that the process of euthanization was not causing the nodule development. Additionally, several pure-line males from
show stock were evaluated in the same manner
as the commercial males.
Testes were collected for microscopic evaluation of the nodules. The affected testes and
normal testes were collected and were placed in
10% neutral buffered formalin for fixation. After fixation, the testes were processed for histological study, using standard and conventional
methods [4].
RESULTS AND DISCUSSION
Initially, 2 flocks of males were examined to
determine the presence of testicular nodules. On
further random sampling of 6 flocks of males,
we observed that the rate of occurrence of these
nodules for individual males ranged from a low
Moyle et al.: TESTICULAR ABNORMALITIES
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Figure 5. Histological preparation showing sperm cells at various stages of spermiogenesis development in a testicular nodule of a mature broiler breeder male.
of 43% to a high of 93% (Figure 2). These flocks
consisted of males from 3 different primary
breeder companies, and flocks were sampled in
3 different states from different integrator flocks
representing different management programs.
We suggest, based on the factors mentioned previously in conjunction with these results, that
the occurrence of nodules in the male breeder
population may be widespread and likely may
not be due to local management or environmental factors. Although all commercial flocks
sampled had significant levels of males with
testicular nodules, these flocks met or exceeded
the expected fertility for their respective ages.
Male lines that are reported to have higher fertility levels (flocks 1, 5, and 7) also had the highest
number of nodules. Therefore, there is a possible genetic relationship, although this cannot be
confirmed. Additional evidence that the occurrence of these nodules may be genetic or developmental is that more than 90% of the nodules
were located only on the left testis (Figure 3). In
addition to the commercial males, a randombred
broiler breeder line from the 1980s was examined, and males were found to have nodules at a
similar level and location. Apparently, this condition has been present since at least the 1980s.
Of the primary breeder companies, company
A had an incidence of occurrence of 65.9%,
company B had an occurrence of 44.8%, and
company C had an occurrence of 41.9%. Because of the small number of flocks sampled,
statistical comparison of breeder companies was
not possible because only 1 flock was evaluated
for company C and 2 flocks were evaluated for
company B. Excluding the males from flock 5
(the young 24.5-wk-old males), the average testicular weight for all flocks was 29.5 g.
The locations of the nodules on individual
testes were random, with nodules located on all
surfaces. Furthermore, nodules were found on
the testes of males that were 18 wk of age and
in males that had not been exposed to a reproductively stimulatory day length, so they were
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Figure 6. Histological preparation showing the nodule located above the tunica albuginea and within the tunica
vaginalis.
sexually immature at the time of collection. Additionally, none of the flocks sampled had any
disease problem reported during their growth or
production cycle.
Of the exhibition line males (n = 37), only
one French Mottled Houdan was found to possess nodules, whereas the others showed no
signs of testicular abnormalities. In addition to
the French Houdans, the other exhibition breeds
examined included Old English Game, Silver
Sebrights, Silkies, Buttercups, and a closed
breeding population of game fowl. The exhibition males used in this study were maintained
under similar lighting conditions and fed the
same feed as the commercial males, with the
only difference being that they were not feed
restricted. This condition was not necessarily
exclusive to commercial breeder males because
the number of pure-line exhibition males studied
was small.
On conducting the histological examination,
we observed that the nodules contained semi-
niferous tubules (Figure 4) that were capable of
producing sperm (Figure 5). Although semen
production was possible, a connection between
the nodules and the testis was not found. It was
also determined that the nodules were separated
from the testis by the tunica albuginea and possibly the interior layer of the tunica vaginalis,
whereas the exterior layer of the tunica vaginalis
encompassed the nodule (Figure 6). If a connection between the nodules and the testis exists, it
would have to pass through the tunica albuginea
and connect with the seminiferous tubules in the
testis.
CONCLUSIONS AND APPLICATIONS
1. Testicular nodules appear to be widespread in the population of breeder
males.
2. The etiology and consequence of nodules on fertility and reproductive performance (positive or negative) is unknown.
Moyle et al.: TESTICULAR ABNORMALITIES
3. It is also unknown whether the seminiferous tubules in the nodules are connected to those in the testis.
4. More data need to be collected so that
statistical correlations can be determined.
REFERENCES AND NOTES
1. Kirby, J. D., and D. P. Froman. 2000. Reproduction in
the male bird. Pages 597–615 in Avian Physiology 5th ed. P.
D. Stukie, ed. Springer-Verlag, New York, NY.
2. Johnson, A. L. 1986. Reproduction in the male. Pages 432–451 in Avian Physiology. 4th ed. P. D. Stukie, ed.
Springer-Verlag, New York, NY.
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3. E. N. Marieb. 2000. The reproductive system. Pages
1070–1117 in Human Anatomy and Physiology. 5th ed. Benjamin Cummings, San Francisco, CA.
4. L. G. Luna. 1968. Manual of Histologic Staining
Methods of the Armed Forces Institute of Pathology. McGraw-Hill Book Co., New York, NY.
Acknowledgments
The authors thank Doug Yoho and David Cross in the
Poultry Science Department of the University of Arkansas,
Fayetteville, for their help in collecting testes and in the
histological preparations. We also thank Annie Donoghue,
Poultry Production and Product Safety Research Unit, Agricultural Research Service, USDA, Fayetteville, Arkansas,
for her advice in the preparation of this paper.