XY Male Pseudohermaphroditism

In book: Sex Chromosomes: Genetics, Abnormalities, and Disorders, Chapter: Chapter 9, Publisher: Nova Science Publishers Inc, Editors: C. N. Weingarten, S.E. Jefferson, pp.165-190


Sex chromosome anomalies are frequently expressed as malformations of the
reproductive organs and constitute sporadic birth defects in domestic animals, which
often leads to infertility. In the presence of a normal karyotype, abnormalities in the
genital tract development can occur. Intersex condition is relatively frequent in goats and
pigs, but less frequent in sheep and dogs. In ruminants, most intersexes conditions
correspond to XX/XY haematopoietic chimaeras and fit in the freemartinism syndrome.
However, sporadically cases of male pseudohermaphroditism are reported that can be
differentiated from the freemartinism syndrome through the karyotype as well as by the
morphological characteristics of the genital tract. These are XY animals that evidence a
variable differentiation of the genital tract, owing to varying degrees of the external
genitalia and paramesonephric ducts associated with inadequate production of
testosterone or Anti-Müllerian Hormone by the fetal testes. Male pseudohermaphroditism
may occur in distinct varieties. Male pseudohermaphroditism includes male to female sex
reversal a condition where, consecutive to a disrupted gonadal differentiation or to an
abnormal development of the Leydig cells, testosterone production is impaired; this
syndrome may present distinct clinical gradations, whether a streak gonad or a
dysgenesic gonad develops. Total absence of androgens induces feminization of the
reproductive tract, while impaired testosterone production and accumulation of
testosterone precursors may originate ambiguous genitalia. In the androgen insensitivity
syndrome, another form of male pseudohermaphroditism also called the testicular
feminization syndrome, despite the presence of testes and a XY karyotype, almost
normal-appearing female phenotypes can be found. This condition is associated to a
defect in the androgen receptor mechanism that leads to a resistance to the testosterone
action at the cellular level in the external genitalia embryonic rudiments. A steroid 5α-reductase deficiency, impairing dihydrotestosterone formation, might also be responsible
for male pseudohermaphroditism. Frequently, animals usually are XY individuals
evidencing female-like or ambiguous external genitalia. Persistency of the Müllerian
ducts is another male pseudohermaphroditism condition, associated with the inadequate
production of Anti-Müllerian Hormone or to the absence of its receptors, which can
reveal female or ambiguous external genitalia.
Based on three distinct forms of male pseudohermaphroditism recently evaluated by
our Clinical Services, the aims of this study includes the morphological, histological and
immunohistochemical description of this condition in normal XY karyotype males (in
both blood and fibroblast samples), and the discussion of the cases through a review of
the literature, in order to improve our knowledge of male pseudohermaphroditism.

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