Sexual development in marsupials: Genetic characterization of bandicoot siblings with scrotal and testicular maldevelopment

Clinical and cytogenetic studies in intersex ewes

“…However, in less evoluted mammals such as the monotremes, genital organs like the pouch, mammary glands and scrotum develop from abdominal skin and are regulated by the sex gene pathway only (Foster et al 1992;Wai-Sum et al 1988). Marsupial intersexes offer a model to study sexual differentiation (Sharman et al 1990;Cooper et al 1993;Hughes et al 1993;Watson et al 2000;Santucciu et al 2003) and can be very useful for the study of intersex eutherian mammals.…”

Clinical and cytogenetic studies in intersex ewes

“…However, in less evoluted mammals such as the monotremes, genital organs like the pouch, mammary glands and scrotum develop from abdominal skin and are regulated by the sex gene pathway only (Foster et al 1992;Wai-Sum et al 1988). Marsupial intersexes offer a model to study sexual differentiation (Sharman et al 1990;Cooper et al 1993;Hughes et al 1993;Watson et al 2000;Santucciu et al 2003) and can be very useful for the study of intersex eutherian mammals.…”

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

“…Indeed, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X inactivation, since no homolog of Xist has so far been identified in marsupials (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the divergence of mammals are probably diverse, and thus, imprinted X inactivation may have evolved independently in marsupials and eutherians (Ohlsson et al 2001).…”

Mammalian X-Chromosome Inactivation: An Epigenetics Paradigm

“…Although the sequence of evolutionary steps described above is very appealing in its simplicity, an alternative hypothesis has to be considered, which is that imprinting of the X-inactivation process may have been imposed more than once during evolution, under selective pressures specific to different mammals. Indeed, despite the apparent similarities in imprinted X-inactivation between marsupials and the extraembryonic tissues of rodents, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X-inactivation: in fact, no homolog of the Xist gene has been identified in marsupials to date (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the development of different mammals are thus likely to be diverse and imprinted X-inactivation may have evolved independently in marsupials and eutherians (Olhsson et al 2001).…”

Clinical and cytogenetic studies in intersex ewes

“…However, in less evoluted mammals such as the monotremes, genital organs like the pouch, mammary glands and scrotum develop from abdominal skin and are regulated by the sex gene pathway only (Foster et al 1992;Wai-Sum et al 1988). Marsupial intersexes offer a model to study sexual differentiation (Sharman et al 1990;Cooper et al 1993;Hughes et al 1993;Watson et al 2000;Santucciu et al 2003) and can be very useful for the study of intersex eutherian mammals.…”

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

“…Indeed, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X inactivation, since no homolog of Xist has so far been identified in marsupials (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the divergence of mammals are probably diverse, and thus, imprinted X inactivation may have evolved independently in marsupials and eutherians (Ohlsson et al 2001).…”

Mammalian X-Chromosome Inactivation: An Epigenetics Paradigm

“…Although the sequence of evolutionary steps described above is very appealing in its simplicity, an alternative hypothesis has to be considered, which is that imprinting of the X-inactivation process may have been imposed more than once during evolution, under selective pressures specific to different mammals. Indeed, despite the apparent similarities in imprinted X-inactivation between marsupials and the extraembryonic tissues of rodents, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X-inactivation: in fact, no homolog of the Xist gene has been identified in marsupials to date (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the development of different mammals are thus likely to be diverse and imprinted X-inactivation may have evolved independently in marsupials and eutherians (Olhsson et al 2001).…”

Clinical and cytogenetic studies in intersex ewes

“…However, in less evoluted mammals such as the monotremes, genital organs like the pouch, mammary glands and scrotum develop from abdominal skin and are regulated by the sex gene pathway only (Foster et al 1992;Wai-Sum et al 1988). Marsupial intersexes offer a model to study sexual differentiation (Sharman et al 1990;Cooper et al 1993;Hughes et al 1993;Watson et al 2000;Santucciu et al 2003) and can be very useful for the study of intersex eutherian mammals.…”

Dosage compensation in mammals: fine-tuning the expression of the X chromosome

“…Indeed, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X inactivation, since no homolog of Xist has so far been identified in marsupials (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the divergence of mammals are probably diverse, and thus, imprinted X inactivation may have evolved independently in marsupials and eutherians (Ohlsson et al 2001).…”

Mammalian X-Chromosome Inactivation: An Epigenetics Paradigm

“…Although the sequence of evolutionary steps described above is very appealing in its simplicity, an alternative hypothesis has to be considered, which is that imprinting of the X-inactivation process may have been imposed more than once during evolution, under selective pressures specific to different mammals. Indeed, despite the apparent similarities in imprinted X-inactivation between marsupials and the extraembryonic tissues of rodents, these mammals show fundamental differences in their early development and extraembryonic tissue formation (Selwood 2001), in their sexual differentiation and determination strategies (Watson et al 2000), and possibly even in their regulation of X-inactivation: in fact, no homolog of the Xist gene has been identified in marsupials to date (Graves and Westerman 2002). The selection forces acting on X-linked gene expression during the development of different mammals are thus likely to be diverse and imprinted X-inactivation may have evolved independently in marsupials and eutherians (Olhsson et al 2001).…”