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Epididymal
changes associated with cryptorchidism in rats
Izzet
Kocak1, Mehmet Dundar1, Nil Culhaci2
Asian J Androl 2001 Dec; 3: 277-280
Keywords:
cryptrorchidism;
epididymis; histology; rats
Abstract
Aim:
1
Introduction
Cryptorchidism is not only associated with changes in the gonads but also the spermatic duct system[1], that may lead to additional fertility problems[2,3]. The histopathological changes of the cryptorchid testis has been precisely described in both the experimental animals and the humans[3]. However, the epididymal alterations associated with cryptorchidism have not been well identified[4,5], only macroscopic changes were observed in the humans[1,6]. In the present study, we examined the histology of the caput epididmides in rats that had been subjected to a newly designed mechanically-induced experimental cryptorchidism. The effect of cryptorchidism on the epididymal growth was also evaluated.
2 Materials and methods
2.1
Animals and treatment
After
approval of the protocol by the local ethics commitee, the animals supplied
by the Experimental Research Center of the University of Adnan Menderes.
Eighteen SD rats weighing 60-70 g were accommodated at an environment
of 252 and
12 h light/12 h darkness.
On day 21 after birth, the rats were weaned, housed in cages of 3 each and had free access to the pellet diet and tap water. They were divided at random into 3 groups of 6 animals each. After an overnight fast, the rats were anaesthetized with an intraperitoneal injection of 2 mg/kg xylazine hydrochloride (Rompun, Bayer, Germany) and 10 mg/kg ketamine hydrochloride (Ketalar, Parke Davis, Eczacibasi, Turkey). In animals of Groups 1 and 2, the left inguinal ring was closed by a 6/0 non-absorbable suture material (Prolen: Ethicon, UK) through the inguinoscrotal approach as described by Dudar et al[7]. The animals of Group 3 were sham operated and served as the controls. On day 60 (Group 1) and day 90 (Groups 2 and 3) after operation, the animals were sacrificed and their testes and epididymides of both sides were removed and the epididymides weighed.
2.2 Histological examination of epididymis
The epididymis was fixed in 10% neutral buffered formalin solution overnight. A transverse segment of the caput epididymis was processed by routine techniques and embedded in paraffin. Sections of 4 m thickness were cut using a standard rotary microtome and stained with hematoxylin-eosin (HE) and Masson's trichrome (MT). The stained slides were examined under a light microscope (Olympus B 50). The diameter of the tubules and the height of the columnar epithelium were measured and the presence or absence of inflammation and fibrosis was evaluated. For each epididymis, 10 tubular cross-sections were randomly selected and measurements were made by means of a micrometric ocular.
2.3 Data analysis
The
data were expressed as meanSEM. Statistical analyses were carried out
using Wilcoxon signed ranks test and Kruskal-Wallis one way analysis of
variance test for comparison between groups. P<0.05 were considered
statistically significant.
3
Results
None of the animals were lost during the study period and no surgical complications occurred. In all the animals of Groups 1 and 2, the left testis was found in the abdominal cavity. The histologic appearance of the cryptorchid caput epididymis was similar in animals of Groups 1 and 2 as exemplified in Figure 1. In the epididymis fibrosis was not found (MT stain) in all the Groups (Figure 2).
Table
1 shows the average weight of the epididymis. The difference between the left
(cryptorchid) and the right epididymis was statistically significant both
in Groups 1 and 2
(P<0.01). The weight difference between the right and left epididymides
was insignificant in Group 3. The cryptorchid epididymides had a significantly
lower weight increase than the contralateral ones and in case of Group
2 also than that of the controls
(P<0.01).
The histologic findings of the cryptorchid and the descended epididymides showed no significant differences with respect to the height of the epithelium (Table2) and the tubular diameter (Table 3).
Figure
1. Cryptorchid caput epididymis at d 60 (HE, 200).
Figure 2. Cryptorchid caput epididymis: tubules
and connective tissue at d 90 (MT, 200).
Table
1. Epididymal weight (mg). cP<0.01and fP<0.01, compared
with the control and right, respectively.
Table 2.
Epithelial height (m) of caput epididymides.
Table 3.
Tubular diameter (m) of caput epididymides.
4
Discussion
Many
models have been introduced in the literature for the induction of cryptorchidism
in experimental animals. In rats, cryptorchidism was usually constituted
by endocrinological[5,8-14] or mechanical[5,8,9,12,15-22]
methods. Congenital cryptorchid mutant (CCM) rats have also been used
as a natural model[23,24]. We introduced
a new model of mechanically-induced cryptorchidism consisting of the closure
of the inguinal canal via inguinoscrotal approach in rats, the validity of
which has been previously documented[7].
Abnormalities
from simple epididymal elongation to more complex forms such as complete
disruption between testes and epididymis have been found in cryptorchid
patients with an overall frequency of 36-90%[6,25]. These malformations may
present problems for sperm maturation and transportation. Nistal et
al[26] shown the presence of dysgenetic rete testis in
patients with cryptorchidism. They concluded that it could have resulted
from incomplete pubertal maturation or primary abnormality of the rete
testis. Moreover, De Miguel et al[27] evaluated the
alterations in the growth of efferent ducts and epididymis in patients
with cryptorchidism from the infancy to the adulthood. Their studies showed
a normal growth pattern of the cryptorchid efferent ducts and ductus epididymides
compared with the controls.
In
rats, the maturation of genital duct begins at the ductus deferens on
day 7 of life, progresses
to more cranial segments with time and ends at the epididymis on day 35
after birth[28]. A current study confirmed the staged postnatal growth
of the epididymis by means of histological and morphometric analysis[29].
The development of the epididymis and accessory glands are under the control
of androgens[30]. However, the efferent ducts and the initial
portion of the caput epididymis do not express androgen receptors[31].
Johansen
et al[4] suggested that the lower weight of the cryptorchid
epididymis is the
result of diminished local androgen stimulation from the ipsilateral testis.
However, the histology and the diameter of the epididymal tubules were
found to be unaltered. In the present study, the histology of the cryptorchid
caput epididymides were found to be similar to that of the the controls,
which may be explained by the androgen-independence of the caput epididymis.
On
the other hand, Zakaria et al[5] emphasized the more
pronounced decrease
in fertility and degeneration of the contralateral testis in the flutamide
induced cryptorchid rats compared to the mechanically-induced cryptorchid
rats. Hypospadias and a small epididymis were also more frequently noted
in the flutamide-treated rats[5,14]. Watts et al[24]
also showed that mechanically-induced cryptorchid SD rats were relatively
resistant to the negative effect of cryptorchidism on fertility than the
CCM rats. However they did not evaluate the associated epididymal lesions.
In this study, we indicated a suppression of the development of the cryptorchid epididymis without evident histological changes. The findings were in accordance with the results of previous studies employing mechanically-induced models of cryptorchidism. These data also support the validity of our model. In conclusion, we propose that this new mechanical model is a convenient method for the investigation of the epididymis in cryptorchidism.
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Correspondence
to: Dr.Izzet
Kocak M.D., Adnan Menderes University Tip Fakltesi Uroloji
Anabilim Dali, 09100 Aydin, Turkey.
Tel: +90-542-232 7032
Fax:
+90-256-212 0146,
E-mail: ikocak@excite.com
Received 2001-10-19
Accepted 2001-12-03
