Journal of Andrology, Vol. 24, No. 5, September/October 2003
Copyright © American Society of Andrology
Development of an Inexpensive Artificial Vagina for Semen Collection from Rabbits
CATHY K. NAUGHTON*,
DAVID R. NELSON
AND
ANTHONY J. THOMAS, JR
From the * Division of Urological Surgery,
Department of Surgery, Washington University School of Medicine, St. Louis,
Missouri; and the Department of Biostatistics
and Epidemiology and the Glickman Urological
Institute, The Cleveland Clinic Foundation, Cleveland, Ohio.
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Correspondence to: Cathy K. Naughton MD, Division of Urologic Surgery,
Washington University School of Medicine, Infertility and Reproductive
Medicine Center, 4444 Forest Park Ave, Suite 3100, St Louis, MO 63108 (e-mail:
naughtonc{at}msnotes.wustl.edu). |
| Received for publication February 6, 2003;
accepted for publication April 6, 2003. |
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Abstract
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The rabbit is well suited for infertility research because of the animal's
size, relatively low cost, and accessibility of the genitalia. There are
several studies reporting sperm count and motility in rabbits; however, no
easily reproducible or inexpensive device for semen collection has been
reported. Herein, we report the construction of an inexpensive, effective
artificial vagina assembled from easily obtainable products that may be used
to collect rabbit ejaculates. This device was used to perform 243 ejaculation
trials on 17 rabbits. Eighty-six percent (209/243) of the trials resulted in
rabbit mounts. Overall, 91% (191/209) of mounts resulted in successful semen
collection. After 60 mounts, a 98% successful ejaculate collection rate was
achieved. The cost of the reusable device is $2.64, plus silicone condoms at
$7.50 each. This practical artificial vagina for semen collection is an
inexpensive and effective means of obtaining semen from rabbits for andrologic
study.
Key words: Semen collection, ejaculate, device
The advantages of the male rabbit as an animal model in reproductive
studies include the animal's size, its reasonable cost, and the accessibility
of the genitalia. Compared to larger animals such as the dog or pig, the
rabbit is easier and less costly to purchase, house, and maintain. Despite its
smaller size, the accessibility of the genitalia is excellent. The
disadvantage of the smaller animal models, such as the rat or mouse, is the
difficulty encountered in studying an important endpoint in andrologic study,
the semen analysis. The evaluation of the ejaculate, however, relies on the
ability to reliably and effectively collect semen from the animal. Although
the collection of rabbit ejaculates with the aid of an artificial vagina has
been previously reported, a commercially available, inexpensive device was not
available at the time of this study. The purpose of this study was to develop
an inexpensive artificial vagina for semen collection from rabbits, which
could be constructed from easily attainable products, and to demonstrate
reliable collection using this device.
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Materials and Methods
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Products for Device Assembly
The products required for device assembly, purchase location, and purchase
prices are shown in Table 1.
Briefly, these products include a 3'' T-connector polyvinyl chloride
(PVC) pipe with 
'' x '' 
''
openings, 2 rubber chair tips (25 mm and 32 mm inner diameters respectively),
a rubber band (3'' x 
''), and a silicone
condom collection device.
Directions for Device Assembly
The 25 mm rubber tip covers the '' T opening of the PVC pipe.
The condom was unrolled and placed through the two '' openings of
the PVC pipe. The opened end of the condom is stretched over the edge of the
pipe and secured with a rubber band (Figure
1). With the open end of the condom pointing down and the closed
end of the condom folded over the other '' opening of the PVC
pipe, warm water (98-100°F) is placed between the PVC pipe and the condom.
The 32 mm rubber tip covers the folded-over end of the condom to contain the
warm water and keep the condom stretched and fixed along the length of the PVC
pipe. The proper assembly of the device creates the "mucosa" of
the artificial vagina (Figure
2).
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Figure 2. After instillation of warm water between the polyvinyl chloride pipe and
the condom, the 32 mm rubber tip covers the folded-over end of the condom and
the mucosa of the artificial vagina is created.
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Directions for Ejaculate Collection
The device is hand-held beneath a sedated doe with the open end pointed in
a caudal direction (Figure 3).
As the buck begins to mount, the device is placed more posteriorly and
inferiorly to allow penetration of the male rabbit into the artificial vagina.
Ejaculation occurs rapidly and the device is removed. Animals were ejaculated
approximately twice weekly. All animals were housed and maintained in the
animal care facility with water and food ad libitum.
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Figure 3. The assembled artificial vagina is hand-held beneath a sedated doe for the
male rabbit to mount.
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Results
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Seventeen male New Zealand rabbits (mean age 33.6 ± 5.3 weeks, mean
weight 4.0 ± 0.3 kg) underwent 243 ejaculation trials (97% of trials by
CKN). The male rabbit was noted to mount the sedated doe in 86% (209/243) of
ejaculation trials. Ejaculated semen was successfully collected using the
described artificial vagina in 91% (191/209) of mounts. Observed ejaculate
collection rate per trial, per mount, and prediction from logistic regression
were calculated. After 60 mounts, a 98% successful ejaculate collection rate
was achieved (Figure 4). The
baseline mean semen volume collected using the device, sperm concentration,
total sperm count, and total motility from 16 rabbits before their undergoing
any andrologic procedures are shown on
Table 2. Of the 65 successful
baseline ejaculate collections, 23% (15/65) were contaminated with urine and
are not represented. The mean semen parameters from 50 available collections
are comparable with those previously reported from mature rabbit ejaculates
(Skinner, 1967).
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Figure 4. Observed ejaculate collection rate per trial, per mount, and prediction
from logistic regression.
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Table 2. Baseline semen analyses of 16 rabbits ejaculates collected with the
artificial vagina prior to andrologic studies.
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Discussion
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The ability to reliably collect ejaculated semen samples from animal models
for andrologic study is critical if semen analysis is one of the defined
investigative endpoints. Rabbits have been regularly used in andrologic
studies because of the relative ease of obtaining ejaculated semen
(Kirton et al, 1966;
Amann and Lambiase, 1967; Skinner, 1967;
Carson and Amann, 1972).
Previous studies note that an artifical vagina was used to collect rabbit
ejaculates; however, the construction of the device or the commercial
acquisition of such a device is not clear from the literature
(Desjardins et al, 1968;
Paufler, 1975; Oshio et al, 1986;
Adams and Singh, 1981). Because
of the difficulty in acquiring an artifical vagina for our planned andrologic
studies requiring semen analysis as an endpoint, we developed our own
artifical vagina for semen collection in rabbits.
Several limitations of this report deserve mention. The semen volumes
attained from this device are lower than previously reported in the
literature. The use of condoms may account for this difference. Other devices
use glass reservoirs for fluid collection, which may enable better retrieval
of the entire specimen. The lower sperm concentrations reported using this
device may be attributable to the use of the condom reservoir or the frequency
of semen collection or both. The rate of urine contamination in our series
appears high. However, as the urine contamination rate in other series is not
as clearly reported, this may be a limitation of ejaculate collection in
rabbits, and not necessarily reflective of the device. Finally, we chose to
elicit the ejaculation reflex with a sedated doe, as reported by other
investigators. Although we used one doe for the entire study, the cost of the
additional animal as well as the sedatives should be considered in the total
cost.
Despite the recognized limitations discussed, our artificial vagina is an
inexpensive device made from easily obtainable products. It enables the
effective and reliable collection of ejaculates from rabbits. The reusable
portion of the device cost $2.64. The most costly portion of the device is the
nonreusable silicone condom ($7.50 each). One condom (purchased at
approximately $150.00 for a box of 20 from HDC; San Jose, Calif) was used for
each ejaculation trial. The materials required to construct this device were
easily attainable from a local Home Depot®. This device has been proven to
be a reliable and effective means of collecting ejaculates from rabbits using
the method described.
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Footnotes
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Supported by Genyx Medical, Inc Aliso Viejo, CA.
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References
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Adams CE, Singh MM. Semen characteristics and fertility of rabbits
subjected to exhaustive use. Lab Anim. 1981; 15:157-161.[Abstract/Free Full Text]
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Carson WS, Amann RP. The male rabbit: VI. Effects of ejaculation
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Desjardins C, Kirton KT, Hafs HD. Sperm output of rabbits at
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Kirton KT, Desjardins C, Hafs HD. Levels of some normal
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