ISSN:1424-8581    

DOI:10.1159/000129938

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

In his previous publications (Matthey, 1963–1966), the author has studied 26 individuals of the pigmy-mouse, Mus (Leggada) minutoides musculoides Temm., from different countries of Africa. This subspecies appears as a polymorphic Robertsonian system: the diploid numbers are equal to 22, 31, 32, 33, 34, while the number of major arms (N.F. = fundamental number) is constant, i.e., 36. The X chromosome is large and nearly metacentric, the Y large and submetacentric. It is demonstrated that these sex chromosomes are formed of an acrocentric X and Y (like those of the domestic mouse) translocated onto two homologous autosomes, which, at meiosis, furnish the pairing segments associated through a true chiasma. No variation of this pattern has been detected. In another species, Mus (Leggada) triton Th., the X chromosome is submetacentric (centromeric index, approximately 0.33), the Y short and acrocentric. In a sample from Bukavu (Congo), 11 females out of 21 show only one typical X, the other X is acrocentric and its length is equal to the length of the long arm of a normal X. The deletion of the short arm is also total or subtotal. No deletion occurs in the 18 males. Recently, five musculoides were obtained from the Ivory Coast. The three males, with diploid numbers of 34, 32, 32, are very similar to seven other specimens of the same country. Both females (2N =32) show only one normal metacentric X chromosome. The other X is submetacentric (I.C. = approximately 0.26) and appears to have lost the major part of one arm. Because of insufficient material, it is not possible to establish whether females homozygous for this deletion and males with the sex chromosome constitution Xd-Y occur in the populatio

ISSN:1424-8581    

DOI:10.1159/000129939

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

A case previously described as an XXXxY male has been re-appraised using 3H-thymidine. A balanced translocation probably involving the long arms of chromosomes 4 and 11 was found; all four X chromosomes were normal. Without quantitative autoradiography, this case would not have been correctly evaluated. The translocation was carried only in the balanced form. The translocated segment did not alter its labelling behaviour in its new site. Apart from the propositus, who had XXXXY sex chromosomes and the typical clinical features of the XXXXY syndrome, a brother and the father, both healthy, had the autosomal translocation. Pedigree and blood group studies showed no apparent abnormalities in the family.

ISSN:1424-8581    

DOI:10.1159/000129940

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

The somatic karyotypes of five crocodilian species are described. These species include Caiman sclerops (spectacled caiman or South American alligator, 2N = 42), Alligator mississippiensis (North American alligator, 2N == 32), Crocoa¦ylus porosus (salt-water crocodile, 2N = 34), Crocodylus niloticus (Nile crocodile, 2N = 32), and Tomistoma schlegeli (false gavial, 2N = 32). Metacentric, submetacentric and telocentric chromosomes were observed in all species tested. Satellites were observed on a submetacentric element of A. mississippiensis, and the apparently identical chromosome with an obvious secondary constriction was found in both C. porosus and C. niloticus. No microchromosomes were found. Possible pathways of chromosomal evolution to explain the observed karyotypic relationships are suggested

ISSN:1424-8581    

DOI:10.1159/000129941

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

Thirteen bovine females, twins to males, were examined in a study of the variability of the freemartin syndrome. The range of intersexuality was from foreshortened uterine horns in the least masculine to complete absence of Müllerian derivatives and development of accessory sex glands in the most masculine. Histological examination revealed no follicular development in the gonads, although juvenile ovarian stroma or testicular tissue or both were present in some. The animals were rated by the degree of masculinization of the reproductive system, which was found to be positively correlated (r = 0.70, p < 0.01) with the percentage of cells of male origin in cultures of peripheral blood from the freematins. The relevancy of these and other data to the general problem of sexual differentiation is discussed. It is concluded that the primary etiological factor of gonadal modification in freemartins is the presence of Y chromosome-bearing cells at the time of differentiation

ISSN:1424-8581    

DOI:10.1159/000129942

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

The length of the human Y chromosome was measured and compared with the mean length of the group E (16–18) chromosomes in ten cells from each individual in the following groups of subjects: 30 control individuals; nine members of three randomly chosen families; ten members of four families with extremely long Y chromosomes; and ten members of three families with extremely long Y chromosomes and a G-trisomic index patient. Measurements were performed a second time on three individuals from the control sample. The results obtained were treated statistically and the following conclusions could be drawn: (1) Analysis of variance indicated good reliability of the method. The mean value of the standard deviations for the variation of the duplicated measurements was 0.027. (2) Although there was a slight intercell variation within the individual, the coefficient of variation was below 5% in all 59 individuals involved in the study. Thus, the length of the Y chromosome was constant within the individual. (3) In the control population there were highly significant interindividual differences, the mean values ranging from 0.55 to 0.88 (Y/E ratio). Although a mean value for the population can be calculated (0.7306 ± 0.012), this mean has little significance because of the wide variability in the length of the Y chromosome. The distribution is of a Gaussian type without step formation. (4) No family showed any statistically significant interindividual variation. It thus could be concluded that the Y chromosome is inherited at a constant length. This applies to randomly chosen families, families with extremely long Y chromosomes and families with long Y chromosomes in which there is an index patient with G-trisomy as well. That such a wide variation in the length of the human Y chromosome is possible can be ascribed to its heterochromatic condition, its presumed paucity of genes and that the greater part of it remains unpaired at meios

ISSN:1424-8581    

DOI:10.1159/000129943

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

A male calico cat was studied cytogenetically and found to have a 43%/57% XY/XX cellular admixture that is thought to have arisen by chimerism. The percentage of XY cells varied in the tissues examined (testes, blood and kidney). Normally descended testes were found which were composed of sterile and fertile seminiferous tubules. The latter had active spermatogenesis and spermatozoa were present in the epididymis, thus accounting for the possibility of ‘fertile calico males’. No female genital structures were pres

ISSN:1424-8581    

DOI:10.1159/000129944

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

The anatomic and cytogenetic findings on 14 intersex animals, including four dogs, four cattle, three goats, two pigs and one cat, are described. Possible explanations of the observed differences between the genetic, gonadal and phenotypic sexes, including a new hypothesis, are discussed.

ISSN:1424-8581    

DOI:10.1159/000129945

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

Four patients with various phenotypic stigmata of gonadal dysgenesis are presented. Cytogenetic investigation revealed each to be mosaic for 45 XO and 46 XO+ minute element stemlines. In two patients the additional element proved to be a small ring, and in the remaining two the supernumerary chromosome was a minute centric fragment. Autoradiographic studies indicated that the ring chromosomes were late replicating, while the metacentric fragments were not. The correlation of the autoradiographic behavior of these abnormal chromosomes with their possible origin is discussed, and a new hypothesis concerning the evolution of the XO karyotype is proposed.

ISSN:1424-8581    

DOI:10.1159/000129946

出版商:S. Karger AG    

年代:1967

数据来源: Karger

摘要:

Autoradiographic studies were done of DNA replication in the unpaired chromosome No. 9 of Eilobius lutescens. The replication sequence is identical in both sexes. The unpaired chromosome comprises approximately 5 % of the haploid complement, corresponding to the original-type X chromosome in the majority of placental mammals. The relation of the odd chromosome to the sex-determining mechanism of this species is discussed.

ISSN:1424-8581    

DOI:10.1159/000129947

出版商:S. Karger AG    

年代:1967

数据来源: Karger