摘要:

A high frequency of spontaneous chromosomal aberrations was found in a phenotypically normal female with no history of either radiation therapy or clinical abnormalities. The aberrations appear to be in a specific chromosome which we identified as a number 10.

ISSN:1424-8581    

DOI:10.1159/000130017

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Evidence is presented for an XX/XY sex-determining mechanism in five species of the genus Uta. All species examined have a somatic diploid complement of 12 macrochromosomes and 22 microchromosomes. The Y chromosome is morphologically distinguishable as the smallest microchromosome in the males. It is paired in metaphase I figures with an X chromosome which is two to three times its size. The size of the X chromosome does not distinguish it from other small microchromosomes in the karyotype.

ISSN:1424-8581    

DOI:10.1159/000130018

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

A method of recording sex chromatin scores with a reproducibility of ±3% at two standard deviations is described. In 25 clinically normal women (control group) the frequency of sex chromatin was 40.8 ± 2.56%. The sex chromatin frequency in eight pregnant women did not differ significantly from that found in the control group (t31 0.05). The sex chromatin frequency in 20 newborn females was significantly lower than that recorded for the control group (t40 = 10.97; P < 0.001). Regression analysis showed that increasing sex chromatin frequency over the first six days of life was strongly related to the effect of days. Reasons are given for attributing this finding to a difference in the buccal mucosal tissue between the newborns and adult females rather than to the effect of different hormonal level

ISSN:1424-8581    

DOI:10.1159/000130019

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Kiley and Wohnus (1968) have reported hybrids between Bufo and Rana. We disagree with their conclusion, in part based on the existence of ‘paternal chromosome markers’ in the maternal karyot

ISSN:1424-8581    

DOI:10.1159/000130020

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Laboratory hybridization has been achieved between two partially sympatric species of jird, Meriones shawi (2n = 44) and M. libycus (2n = 44). The parental karyotypes differ by at least three autosomal rearrangements and a remodeling of the X chromosome. F1 hybrid karyotypes contain a haploid set derived from each parent, and the species origin of four chromosomes, including the X, can be identified. The FI females are fertile, whereas F1 males are infertile owing to completely or markedly diminished spermatogenesis. The F1 females backcrossed with M. shawi males are fertile and produce normal-sized litters with normal sex ratios; male progeny from this cross have normal spermatogenesis and are fertile. The F1 females backcrossed with M. libycus males exhibit reduced fertility, small litters and an absence of male offspring. The taxonomic status of M. shawi and M. libycus is evaluated with respect to the chromosomal and hybridization data, and the isolating mechanisms involved with speciation in Meriones ate considered.

ISSN:1424-8581    

DOI:10.1159/000130021

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Genetic studies have shown that the dominant gene for polledness found in the Saanen breed will, when homozygous, lead to pseudohermaphrodism, testicular hypoplasia or epididymal sperm granuloma and to an abnormal sex ratio (excess of males). An analysis of chromosomal constitution and nuclear appendages in peripheral leucocytes and tissue cultures of 17 pseudohermaphrodites, 10 males with epididymal sperm granuloma and 3 males with testicular hypoplasia was carried out. Sex chromatin could not be unequivocally distinguished in buccal or urinary bladder smears owing to the presence of other large chromatin masses. In no case was any trace of ovarian tissue found. One pseudohermaphrodite was a blood chimaera (XX/XY). This animal, a typical freemartin, was indistinguishable in anatomy or histology from the other pseudohermaphrodites. The chromosomal constitution and nuclear appendages of the remaining 16 pseudohermaphrodites and of the males with testicular hypoplasia were those of a genetic female. It is concluded that the pseudohermaphroditic effect of the polled gene is limited to genetic females and that males with testicular hypoplasia are actually genetic females showing an extreme pseudohermaphroditic effect. The abnormal sex ratio characteristic of the Saanen breed is thus shown to be a trivial consequence of classifying extreme pseudohermaphrodites as males. The chromosomal constitution and nuclear appendages of the males with epididymal sperm granuloma were those of a normal male. Hence the genetic factor for polledness, when homozygous in genetic males, can lead to the development of epididymal sperm granuloma.

ISSN:1424-8581    

DOI:10.1159/000130022

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

In five heterosexual male bovine twins and three freemartins, all not older than three months, XX/XY chimerism in the blood and gonads has been found. One heterosexual male bovine triplet showed at the age of 18 or 22 months XX/XY chimerism in the blood but not in the testes. In another male co-twin of a freemartin, XX/XY chimerism has been detected in the blood and the testes (at biopsy) at the age of two months. In the same animal, the blood chimerism was still present at the age of 18 months, whereas the chimerism of the testes had vanished at that time. Therefore, it can be concluded that, in the course of time, the XX cells of the testes have been eliminated. This elimination, which possibly occurs in embryonic life, partially explains why male co-twins of freemartins do not have malformations of the genital organs and are fertile. Possibly, the XY cells of the testes have an eliminating influence against neighbouring cells with an XX karyotype. The eliminating effect could be directed at the two active X chromosomes of these germ cells. The hypothesis would also account for the observation that blood lymphocytes with an XX karyotype, which have, according to the Lyon hypothesis, only one active X chromosome, are not eliminated with time.

ISSN:1424-8581    

DOI:10.1159/000130023

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

Chromosome studies were carried out on metaphases from leukocyte cultures of 25 Ainu from Hokkaido and three Ainu, three Oroks and one Gilyak from Sakhalin. The chromosomes of four additional Hokkaido Ainu were studied in cells from skin cultures. No significant departures from the chromosome complement characterizing other human populations were detected.

ISSN:1424-8581    

DOI:10.1159/000130024

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

A phenotypically normal male mouse, investigated because it was sterile, was found to possess 41 chromosomes. A karyotypic analysis indicated the extra element was one of the smallest chromosomes, almost certainly the Y. X-Y bivalents, Y-Y bivalents and XYY univalents were seen in meiotic metaphase I cells, and it was therefore concluded that the extra chromosome was indeed the Y. Spermatogenesis tended to break down after meiosis I, but a few spermatids and sperm were observed.

ISSN:1424-8581    

DOI:10.1159/000130025

出版商:S. Karger AG    

年代:1969

数据来源: Karger

摘要:

A sterile mouse was found to be a chromosomal mosaic with two cell lines, one containing 39 chromosomes, the other 41. Both types were present in approximately equal numbers in the bone marrow, but the 41-chromosome line alone was identified in spermatogonia and spermatocytes. Evidence from chromosome morphology at mitotic metaphase and from spermatocytes at diakinesis and metaphase I identified the two cell-lines as XO and XYY respectively. The alternative possibilities of exclusion of the XO line from the seminiferous elements by chance and by selection are discussed and the latter interpretation favoured. The possibility is raised that the Y chromosome of mammals carries genetic information essential for normal spermatogenesis, as distinct from its established function in embryonic gonadal determination.

ISSN:1424-8581    

DOI:10.1159/000130026

出版商:S. Karger AG    

年代:1969

数据来源: Karger