ISRAEL JOURNAL OF
VETERINARY MEDICINE
CRYPTORCHIDISM ASSOCIATED WITH 78,XY/79,XXY
MOSAICISM IN DOG.
Vol. 56 (2) 2001
B. Goldschmidt1, K.B. El-Jaick2, L.M. Souza1, E.C.Q. Carvalho1, V.L.S.
Moura3, I.M. Benevides Filho4.
1. Veterinary Faculty, Federal Fluminense University, Vital Brazil Filho street, n. 64, Niteroi, Brazil
2. Autonomous Veterinary and 3.Human Cytogenetic Laboratory, Fernandes Figueiras Institute,
FIOCRUZ
Abstract
Cytogenetic analysis of a Poodle dog with bilateral cryptorchidism revealed a variation of the
Klinefelter Syndrome (1). It presented a XY/XXY complement in blood lymphocytes and in the testis.
Histopathological findings presented similar features to those of XXY human males (2).
Introduction
Cryptorchidism is a defect which occurs in many species and, in most of them, can be diagnosed at
birth. In dogs, However, the testes are still inside the abdomen at birth, reaching their final position in
the scrotum at 35 to 40 days later (3).
Specific causes of cryptorchidism in the dog are unknown (4). A disorder of MIF (Mullerian Inibitor
Factor) secretion has been hypothesized in miniature Schnauzers as causing the presence of both a
uterus and cryptorchidism (5). Canine cryptorchidism has been described as a sex-limited trait (6,7)
and is mostly bilateral. A single autosomal recessive gene has been cited as a probable cause(6). The
wide breed distribution of cryptorchidism in the dog suggests that inheritance may not be the only
factor (8).
Klinefelter syndrome is the most common form of primary testicular failure involving both
spermatogenesis and androgen secretion, and has been reported in man(9,10) and many other
mammalian species: mouse (11), Chinese hamster (12), pig (13), bull (14), sheep (15), goat (16), horse
(17), cat (18) and dog (5,19,20,21). Most XXY humans are phenotypic males (22) and most of the
XXY dogs have been described as intersex animals (23).
The XY/XXY complement, was presented as a variation of the Klinefelter syndrome(1) , and in this
condition, the secondary sex characteristics were less affected than in patients with XXY syndrome.
The present paper describes a Poodle dog with bilateral cryptorchidism, associated with
78,XY/79,XXY mosaicism.
Materials and Methods
A one year old male Poodle was detected with bilateral cryptorchidism. Metaphase chromosomes were
prepared from peripheral blood lymphocyte culture (24). Cells from the two gonads were cultured for
cytogenetic investigation (25). Histological sections were prepared from the testis and stained with
haematoxylin and eosin.
Results
Cytogenetic analysis showed a 78,XY/79,XXY chromosome complement (figure 1). This mosaicism
was both on peripheral blood lymphocyte culture and gonadal tissue. Lymphocyte analysis revealed
18% of metaphases 79,XXY. The right testis showed 30% of cells 79,XXY while the left one presented
12%.
Histopathological study of both gonads revealed testis with expressive vacuolation of the seminal cells
and total absence of sperm cells (figure 2) The interstitium appeared relatively slaked, revealing in a
few microscope fields, small nests of Leydig cells (figure 3).
FIGURE 1: Two
metaphases (prepared
from peripheral blood
lymphocyte culture)
at the same
microscope camp:
one of them with XY
sexual chromosomes
and other with XXY
sexual chromosomes,
demonstrating the
mosaicism in a poodle
dog with bilateral
cryptorchidism.
Arrows indicate the
sex chromosomes.
FIGURE 2:
Photomicrogaph of an
H&E stained section
of testis from a Poodle
with cryptorchidism
and mosaicism
78,XY/79,XXY,
demonstrating
expressive vacuolation
of the seminal cells
and total absence of
sperm cells.
FIGURE 3:
Photomicrograph of
H&E-stained section
of testis from the same
dog, showing small
nests of Leydig cells
and a relatively slaked
interstitium.
Discussion
Bilateral cryptorchidism in dogs was associated with the Klinefelter syndrome in the past (5) and also
with 78,XY/79,XXY chromosome constitution. The presence of mosaicism reveal the absence of
mitotic disjunction at some time during embryonic development.
The variant form of Klinefelter’s syndrome more frequently found is the XY/XXY mosaicism (1). The
influence of the normal cell in modifying the full expression of this syndrome, will be illustrated by
contrasting the findings in patients with XY/XXY mosaicism with those in patients with the classic
form. In some patients, the XXY cell line could be identified only in testicular tissue, reinforcing the
requirement of cytogenetic investigation in dogs with cryptorchidism
The fact that the right testis presented higher number of 79,XXY cells (30%) than the left testis (12%),
is probably related to the cell distribution in the gonad during embryonic development and did not
reflect morphological differences between the gonads.
The distance covered by the testis into the scrotum is greater in dogs than in man. Although the
cryptorchidism may be considered rare in the human Klinefelter syndrome (27), in dogs it may be more
frequent.
The descent process of the testis in dogs is going from a localization near the kidneys until the scrotum
and doesn’t occur in the prenatal phase like in other species including the human beings (4).
Many experiments have been performed to identify the factor responsible for the descent of the testis in
dogs. There are indications that the activity of the gubernaculum testis or the consequent descent of the
testis is regulated by an androgenic factor, not yet identified, secreted by the Sertoli cells or germ cells
and that testosterone has an important action on the regulation of gubernacular regression at the intrainguinal phase of descent (26).
The Leydig cells, responsible by testosterone production are histologically and functionally abnormal
in Klinefelter’s syndrome. The abnormal functioning of these cells are evident in individuals with
Klinefelter’s syndrome by low levels of plasmatic testosterone and low response to GCH
administration (gonadotrophine corionic hormone) (27).
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