Al. Barlow et Ma. Hulten, COMBINED IMMUNOCYTOGENETIC AND MOLECULAR CYTOGENETIC ANALYSIS OF MEIOSIS-I HUMAN SPERMATOCYTES, Chromosome research, 4(8), 1996, pp. 562-573
We have used a combination of immunocytogenetic and molecular cytogene
tic technology on human spermatocytes to investigate (1) meiosis I chr
omosome pairing, and (2) organization of synaptonemal complex (SC)-ass
ociated chromatin with respect to whole chromosome paints, unique DNA
sequences and repetitive DNA of heterochromatic blocks, centromeres an
d telomeres. It is evident that synapsis normally starts at the termin
i of homologues. In general, synapsis proceeds synchronously from term
ini towards the centre of bivalents without any indication of intersti
tial initiation. Some aberrant meiosis I spermatocytes showed asynchro
nous pairing, demonstrating not only large differences in the degree o
f SC formation between bivalents, but also chromosome alignment withou
t synapsis as well as clear interstitial synaptic initiation. it may b
e the case that alignment normally takes place along the entire length
of homologues before synapsis occurs and that the potential for synap
tic initiation exists along the length of chromosomes. Telomeric seque
nces were seen tightly associated with the SCs, as might be expected c
onsidering their kinetic properties in relation to the nuclear membran
e, Other repetitive DNA, i,e. centromeric alpha-satellites and classic
al satellites of the heterochromatic blocks 1qh and 9qh, were all foun
d to form loops that are associated with SCs only at their bases. A un
ique DNA cosmid probe (21q22.3) was found to produce a hybridization p
attern consisting of spots located outside SC. The fluorescence in sit
u hybridization (FISH) signals of these spread DNA sequences have a gr
anular appearance, probably reflecting the pattern of coiling and chro
matin condensation of the target DNAs.