A 39,X/40,XY/41,XYY mosaic male mouse

Abstract

Cytogenetic analyses of bone marrow and gonadal cells in a male mouse, which appeared to be normal, revealed mosaicism in both tissues. Three chromosome complements, 39, X, 40, XY, and 41, XYY, were found in both bone marrow and spermatogonia, while only the last two complements were found in spermatocytes. In this mouse, unlike in the human, the XYY cells showed a proliferative advantage over the XY cells. In XYY cells at diakinesis/metaphase I the gonosomes showed all possible types of association, and a pairing advantage of the X chromosome was clearly demonstrated. The fertility of the mouse was not determined. However, since the epididymal sperm count was reduced by only 55% and the incidence of sperm head abnormality was near normal, it is not evident that the mouse was sterile.

XYY spermatogenesis in XO/XY/XYY mosaic mice

“…XYY MI spermatocytes have been common. In the mosaics described by Das and Behera (1984) and Searle and Wilkinson (1986), there was no preferential loss of XYY cells prior to MI. whereas in the present mosaics a dramatic reduction in the fre quency of XYY cells occurred during pachytene.…”

An analysis of meiotic impairment and of sex chromosome associations throughout meiosis in XYY mice

“…The relative frequencies of the various sex chromosome associations at diakinesis and the first meiotic metaphase (MI) are very heterogeneous and have been taken to suggest either random synapsis of the three sex chromosomes (resulting in twice as many XY bivalent/Y univalent as X univalent/YY bivalent associations) or a synaptic advantage of the X over either Y chromosome (Cattanach and Pollard, 1969;Evans et al, 1969Evans et al, , 1978Rathenberg and Müller, 1973;Manna and Roy, 1980;Das and Kar, 1981;Das and Behera, 1984). However, as is evident from the study of Rodriguez and Burgoyne (2000), the frequencies of the various sex chromosome associations at diakinesis/MI bear little resemblance to those at pachytene, when synapsis is first completed.…”

Sex chromosome configurations in pachytene spermatocytes of an XYY mouse

“…Of these cells, 19 had an XYY trivalent, 18 had an X univalent and YY bivalent, 1 had an XY bivalent and Y univalent, and 1 had X, Y, Y univalents. There is an intriguing contrast between these observations which indicated preferential involvement of the Y chromosomes in synapsis and the metaphase I data which suggested either random X and Y association (Rathenberg & Muller, 1973;Das & Kar, 1981) or preferential X chromosome involvement (Evans et al 1978;Das & Behera, 1984). This brief report describes the synaptic behaviour of the sex chromosomes in pachytene spermatocytes of another XYY male.…”

“…In contrast, Evans et al (1978) concluded the X chromosome had an overall pairing advantage as it was present as a univalent on fewer occasions than expected of random association. Das & Behera's (1984) data also indicated a paucity of X chromosome univalence.…”

“…Their rarity has been the principal factor limiting study of the influence of this type of sex chromosome aneuploidy on meiotic chromosome behaviour. To date, only 7 XYY male mice have been examined (Cattanach & Pollard, 1969;Rathenberg & Muller, 1973;Evans et al 1978;Das & Kar, 1981) although additional data have been obtained from an X0/XYY mosaic male (Evans et al 1969) and from X0/XY/XYY mosaic animals (Das & Behera, 1984;Palmer et al 1990). In XYY spermatocytes, 4 types of sex chromosome configuration at metaphase I have been found: an XYY trivalent; an XY bivalent and Y univalent; an X univalent and YY bivalent; and X, Y, Y univalents.…”