Meiotic behaviour of the sex chromosomes in three patients with sex chromosome anomalies (47,XXY, mosaic 46,XY/47,XXY and 47,XYY) assessed by fluorescence in-situ hybridization*

Abstract

Meiotic studies using multicolour fluorescent in-situ hybridization (FISH) and chromosome painting were carried out in three patients with sex chromosome anomalies (47,XXY; 46,XY/47,XXY and 47,XYY). In the two patients with Klinefelter syndrome, although variable percentages of XXY cells (88.5 and 28.3%) could be found in the pre-meiotic stages, none of the abnormal cells entered meiosis, and all pachytenes were XY. However, the abnormal testicular environment of these patients probably resulted in meiotic I non-disjunction, and a certain proportion of post-reductional cells were XY (18.3 and 1.7%). The fact that none of the spermatozoa were XY also suggests the existence of an arrest at the secondary spermatocyte or the spermatid level. In the XYY patient, most (95.9%) premeiotic cells were XYY. The percentage of XYY pachytenes was 57.9%. The sex chromosomes were either in close proximity (XYY) or the X chromosome was separated from the two Ys (X + YY). A high proportion (42.1%) of post-reductional germ cells were XY. However, only 0.11% of spermatozoa were disomic for the sex chromosomes. In this case, the data suggest the existence of an arrest of the abnormal cells at the primary and the secondary spermatocyte or the spermatid level, giving rise to the continuous elimination of abnormal cells in the germ-cell line along spermatogenesis. The fact that the proportion of diploid spermatozoa was only increased in one of the three cases (XXY) is also suggestive of an arrest of the abnormal cell lines in these patients. The two apparently non-mosaic patients were, in fact, germ-cell mosaics. This suggests that the cytogenetic criteria used to define non-mosaic patients may be inadequate; thus, the risk of intracytoplasmic sperm injection in apparently non-mosaics may be lower than expected.

Ploidy of spermatogenic cells of men with non-mosaic Klinefelter’s syndrome as measured by a computerized cell scanning system

“…According to others, primary 47,XXY spermatocytes are unlikely to complete meiosis, and spermatozoa of KS men arise from the patches of 46,XY spermatogonial stem cells in the testes that are affected by a compromised testicular environment and produce a high rate of aneuploid sperm due to meiotic errors. Bergere et al [4], Blanco et al [17], and Sciurano et al [20], who looked at pachytene figures of positive KS patients, found that almost all of them (94.5-100 %) were 46,XY and deduced that these cells are the only active cells. They were reinforced by Egozcue et al [35] who identified the absence of 46,XY spermatogonia in patients negative for spermatids and spermatozoa, and by Mroz et al [36] who showed a clear absence of meiotic competence of 47,XXY cells in mice.…”

“…They were reinforced by Egozcue et al [35] who identified the absence of 46,XY spermatogonia in patients negative for spermatids and spermatozoa, and by Mroz et al [36] who showed a clear absence of meiotic competence of 47,XXY cells in mice. Small quantities of studied germ cells such as 20-100 spermatogonia and primary spermatocytes in very few biopsies [1][2][3][4][5]8], as well as technical shortcomings, preclude a definite conclusion [1,4,17,19,20,23] (the study by Yamamoto et al [23] (2002) included 12 biopsies, but lacked information regarding the number of meiotic cells). The CCSS technique, which is based on corresponding size and morphology of the cells and their FISH images, enabled an extended study at three levels:…”

“…unable to enter and complete meiosis, possibly because of the presence of two functional X chromosomes [16], and assume that the origin of spermatozoa is from normal 46, XY germ cells that are located in the testes [4,17,18]. Others believe that mitotic and meiotic progression of these cells is possible [5,18].…”

“…Researchers have used various ways to find out the cause for the presence or absence of these euploid and aneuploid spermatozoa and to investigate their origin and precursor cells. Since in vitro experiments are not yet available, some have looked at progenitor germ cells and the meiotic process itself in vivo, for example, using fluorescence in situ hybridization (FISH) on pachytene figures (the meiotic stage during which crossing-over occurs) [4,17,1,[19][20][21][22][23]. Others [5-7, 11, 24] have used an indirect approach and have deduced the most likely hypothesis from FISH results on spermatozoa, i.e., the Bend product^of the meiotic process.…”

Sperm retrieval from patients with nonmosaic Klinefelter’s syndrome by semen cytology examination

“…Degeneration of the seminiferous tubules of 47,XXY males is a frequent and well-studied phenomenon, although some tubules with spermatogenesis may be present in adults (Aksglaede et al, 2006). Studies on meiosis concluded that XXY cells are unable to complete the meiotic processes leading to mature spermatozoa (Blanco et al, 2001;Hall et al, 2006). XXY cells cannot efficiently align during meiosis, and unsynapsed chromosomes would disturb the meiotic checkpoint and trigger apoptosis at the pachytene spermatocyte stage (Aksglaede et al, 2006).…”