In many species, including mammals, sex determination is genetically based. The sex chromosomes that individuals carry determine sex identity. Although the genetic base of phenotypic sex is determined at the moment of...In many species, including mammals, sex determination is genetically based. The sex chromosomes that individuals carry determine sex identity. Although the genetic base of phenotypic sex is determined at the moment of fertilization, the development of testes or ovaries in the bipotential early gonads takes place during embryogenesis. During development, sex determination depends upon very few critical genes. When one of these key genes functions inappropriately, sex reversal may happen. Consequently, an individual＇s sex phenotype may not necessarily be consistent with the sex chromosomes that are present. For some time, it has been assumed that once the fetal choice is made between male and female in mammals, the gonadal sex identity of an individual remains stable. However, recent studies in mice have provided evidence that it is possible for the gonadal sex phenotype to be switched even in adulthood. These studies have shown that two key genes, doublesex and mad-3 related transcription factor 1 （Dmrtl） and forkhead box L2 （Foxl2）, function in a Yin and Yang relationship to maintain the fates of testes or ovaries in adult mammals, and that mutations in either gene might have a dramatic effect on gonadal phenotype. Thus, adult gonad maintenance in addition to fetal sex determination may both be important for the fertility.展开更多
Since the outbreak of 2019 novel coronavirus infection (2019-nCoV) in Wuhan City,China,by January 30,2020,a total of 9692 confirmed cases and 15,238 suspected cases have been reported around 31 provinces or cities in ...Since the outbreak of 2019 novel coronavirus infection (2019-nCoV) in Wuhan City,China,by January 30,2020,a total of 9692 confirmed cases and 15,238 suspected cases have been reported around 31 provinces or cities in China.Among the confirmed cases,1527 were severe cases,171 had recovered and been discharged at home,and 213 died.And among these cases,a total of 28 children aged from 1 month to 17 years have been reported in China.For standardizing prevention and management of 2019-nCoV infections in children,we called up an experts' committee to formulate this experts' consensus statement.This statement is based on the Novel Coronavirus Infection Pneumonia Diagnosis and Treatment Standards (the fourth edition) (National Health Committee) and other previous diagnosis and treatment strategies for pediatric virus infections.The present consensus statement summarizes current strategies on diagnosis,treatment,and prevention of 2019-nCoV infection in children.展开更多
文摘In many species, including mammals, sex determination is genetically based. The sex chromosomes that individuals carry determine sex identity. Although the genetic base of phenotypic sex is determined at the moment of fertilization, the development of testes or ovaries in the bipotential early gonads takes place during embryogenesis. During development, sex determination depends upon very few critical genes. When one of these key genes functions inappropriately, sex reversal may happen. Consequently, an individual＇s sex phenotype may not necessarily be consistent with the sex chromosomes that are present. For some time, it has been assumed that once the fetal choice is made between male and female in mammals, the gonadal sex identity of an individual remains stable. However, recent studies in mice have provided evidence that it is possible for the gonadal sex phenotype to be switched even in adulthood. These studies have shown that two key genes, doublesex and mad-3 related transcription factor 1 （Dmrtl） and forkhead box L2 （Foxl2）, function in a Yin and Yang relationship to maintain the fates of testes or ovaries in adult mammals, and that mutations in either gene might have a dramatic effect on gonadal phenotype. Thus, adult gonad maintenance in addition to fetal sex determination may both be important for the fertility.
文摘Since the outbreak of 2019 novel coronavirus infection (2019-nCoV) in Wuhan City,China,by January 30,2020,a total of 9692 confirmed cases and 15,238 suspected cases have been reported around 31 provinces or cities in China.Among the confirmed cases,1527 were severe cases,171 had recovered and been discharged at home,and 213 died.And among these cases,a total of 28 children aged from 1 month to 17 years have been reported in China.For standardizing prevention and management of 2019-nCoV infections in children,we called up an experts' committee to formulate this experts' consensus statement.This statement is based on the Novel Coronavirus Infection Pneumonia Diagnosis and Treatment Standards (the fourth edition) (National Health Committee) and other previous diagnosis and treatment strategies for pediatric virus infections.The present consensus statement summarizes current strategies on diagnosis,treatment,and prevention of 2019-nCoV infection in children.
