Sex chromosome aneuploidy examples.
XXY (Klinefelter’s syndrome) – male calico-tortoiseshell cats. Colours require both X chromosomes so have XXY.
XO (Turner’s syndrome) – described in horses.
Freemartinism.
Male/female twin pregnancies»_space; placental vascular connections from between the placentae»_space; increases androgens and effects of SRY gene»_space; reduces development of female genitalia and masculinises female twin.
She gets small ovaries due to absence of or reduction in germ cell number, partially converted into testicles.
Small vulva due, prominent clitoris, short, blind ending vagina. Other Mullerian duct derivatives vary. Wolffian duct structures may be present.
Extreme XX disorder.
Complete sexual reversal – sex chromosomes are XX and phenotype is male. Reported in dogs, pigs and goats.
XY disorders of sexual development.
– Example.
Majority are XY, SRY+, testicular disorders with a female phenotype.
Called sex reversal syndrome, androgen insensitivity or testicular feminisation syndrome.
– Normal XY karyotype but no intracellular androgen receptors due to a mutation that produces a deficiency of intracellular androgen receptors.»_space; No androgenic effect»_space; Small testicles.
Tumours of the surface of coelomic epithelium.
Common in dogs.
Papillary cystadenoma or cystadenocarcinoma.
Often bilateral, up to 10cm diameter.
Cauliflower-like.
If malignant, peritoneal spread (“seeding”) possible – Lymphatic blockage»_space; ascites.
Cystic endometrial hyperplasia.
Predisposition – excessive and prolonged estrogenic stimulation.
Due to joint actions of oestrogens and progesterone.
Dogs, cats, cattle affected.
In cattle, related to follicular cysts or granulosa tumours – oestrogens increased.