Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. |l

RECENT CYTOGENETIC STUDIES ON INTERSEXES

IN DOMESTIC MAMMALS

During the last few years several studies have been made
on the cytogenetics of intersexes and related conditions in do-
mestic mammals. The number of cases in each species is still
very limited, and, with the exception of the cow, are so few
they can still be listed individually. I will consider each

species in turn.

Cow
The cytogenetics of intersexuality has been studied in the
cow more extensively than in any other species, because of the
frequency of freemartinism. Thus no attempt will be made to
enumerate all cases. There is now ample evidence to show that
freemartins in the cow have an XX/XY sex chromosome constitu-
tion. Many examples of intersexual cattle with XX/XY sex chromo-
somes have been described. Table 1 shows the cases of XX /XY
chimerism which fulfill the following criteria of freemartinism:
(a) All freemartins are known cases of heterosexual
multiple births,
(b) All males are normal from the point of view of gonadal
and phenotypic sex,
(c) Cultures of blood leucocytes from at least two hetero-
sexual litter mates contain XX and XY cells,

(d) Cultures of other types of cells do not show chimerism.

845