Synaptonemal complex karyotyping in spermatocytes of the Chinese hamster (Cricetulus griseus)

Abstract

The X and Y chromosome axes have a distinctive morphology at pachytene and are clearly distinguishable from autosomal SCs. The X and Y are totally unpaired at late zygotene when most of the autosomes are synapsed; however, their attachment points at the presumptive SC end are closely apposed. The X and Y axes pair to form a length of SC that is somewhat shorter than the unpaired portion of the Y. Unpaired axes may appear thin and sometimes double, or may thicken to form fusiform bulges that are sometimes hollow: two on the X and one on the Y. Discrete differentiations, tentatively identified as kinetochores, are often visible at the proximal end of the SC on the Y axis, and also between the fusiform differentiations on the X axis. Additional differentiations, in the form of loops and densely staining granular excrescences form on the X axis and sometimes on the Y. A further differentiation appears as a cloud-like sheath around the distal end of the X axis, often in association with a bi-lobed dense body. At late pachytene, the XY-SC remains intact, but the unpaired X and Y axes develop side branches. Just before diplotene, while the autosomal SCs are still intact, the XY-SC is lost, although the axes persist and remain together at the attachment point of the SC. The X and Y differentiations form a logical temporal sequence when grouped according to progressive structural complexity. The morphological types may serve as markers for the sub-stages of pachytene.

Inter- and intra-plant SC length variation in Crepis capillaris

“…This study recorded a 1 .8x range of SC lengths among pachytene oocytes and also concluded that SC lengths initially decreased during early to mid pachytene before extending again during late pachytene. A similar pattern of change in SC length was described in hamster spermatocytes, where sub-stages of pachytene Carmi et al (1978) were defined by changes in XY morphology (Moses et a!., 1977 (Gillies, 1983). The ranges of SC lengths observed in Crepis capillaris are similar to those described in maize which supports the contention that the pachytene nuclei analysed in the present study represent the entire range of pachytene.…”

Chromosome pairing and chiasma formation in allohexaploid wheat, Triticum aestivum analyzed by spreading of meiotic nuclei

“…The staining was monitored under phase contrast or conventional optics and, when the staining was considered appropriate, the coverslip was floated offand the slides washed in distilled water and dipped for 10 sec in 0.4% Kodak Photoflo 200 adjusted to pH 8.2 with borate buffer before air drying. Some spreads were stained with phosphotungstic acid (PTA) as described by MOSES (46). One part of aqueous 4% PTA was mixed with three parts of 96% ethanol and the slides were stained for 10 min in the mixture whereafter they were washed in 96% ethanol and air dried.…”

Sex-autosome translocations: meiotic behaviour suggests an inactivation block with permanence of autosomal gene activity in Phyllostomid bats

“…Despite this, its condensation is quite differentiated from that of the autosomal segments in Artibeus lituratus. According to SOLARI (1974), SHARP (1982) and MOSES (1977), species analyzed that have multiple systems and that present variations in the condensation of the sex axes, conserve these types of modification in taxonomic groups. Species of Macropus (marsupial) have intense condensation in the axes of the sex chromosomes similar to that of eutherians (MOSES 1977) with almost identical modifications.…”

“…According to SOLARI (1974), SHARP (1982) and MOSES (1977), species analyzed that have multiple systems and that present variations in the condensation of the sex axes, conserve these types of modification in taxonomic groups. Species of Macropus (marsupial) have intense condensation in the axes of the sex chromosomes similar to that of eutherians (MOSES 1977) with almost identical modifications. Perhaps due to the lack of a broader analysis of TUCKER and BICKHAM (1986), in Stenodermatinae bats, it was not possible to observe differentiation in the condensation of the original axes of X and Y.…”