Human meiosis V. Substages of pachytene in human spermatogenesis

Holm, Preben Bach; Rasmussen, Søren W.

doi:10.1007/bf02911917

Cited by 24 publications

(27 citation statements)

References 18 publications

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“…The total complement length of the nuclei amounted to 213 and 206 ~tm, which is about the same as the mean complement length of 198/am measured at late (stage 7) pachytene (9).…”

Section: Early Diplotenesupporting

confidence: 70%

“…The analysis was performed on biopsies from three normal fertile men undergoing vasectomy, the biopsies being the same as those used in previous studies of the zygotene and pachytene stages in human spermatogenesis (6,9,18, cases [3][4][5]. Twelve nuclei covering the period from early diplotene to late diakinesis -prometaphase I were completely reconstructed, while five nuclei were serial sectioned and photographed but not reconstructed.…”

Section: Methodsmentioning

confidence: 99%

“…The procedures used for fixation, staining, electron microscopy and the subsequent reconstruction of the chromosome complement, as well as the methods for measuring the synaptonemal complex length, have been described previously (6,9,18). …”

Section: Methodsmentioning

confidence: 99%

“…Additional characteristics of early diplotene cells are the following: (Figures I and 2): (A) The nuclei are large and spherical and the centrioles which have duplicated during pachytene (9) are located in the vicinity of each other, one of them positioned far~her away from the nuclear envelope than the other. Both pairs are surrounded by a granular matrix from which a few microtubules emerge.…”

Section: Early Diplotenementioning

confidence: 99%

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Human meiosis VII. Chiasma formation in human spermatocytes

Holm

Rasmussen

1983

Carlsberg Res. Commun.

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The diplotene and diakinesis stages in human spermatocytes have been analyzed by serial sectioning and three dimensional reconstruction of 17 nuclei covering the period from early diplotene to prometaphase I. The analysis has permitted the following observations and conclusions: l) The diplotene and diakinesis stages in human spermatocytes are very short but can be subdivided into early, mid and late substages on the basis of changes in nuclear shape, centriolar behaviour, synaptonemal complex elimination and bivalent contraction. The ultrastructure of the autosomal bivalents and the XY bivalent is described. 2) Synaptonemal complex elimination is initiated at a low number of sites at early diplotene, creating about 70 remaining stretches of synaptonemal complex. Degradation continues during diplotene but is confined to the ends of these segments as the total number of distinct segments is unchanged during diplotene. The distribution of the segments among and along the bivalents is similar to that of crossovers and chiasmata, suggesting that the crossovers are contained in these segments. In virtually all XY bivalents, a short synaptonemal complex segment combines the homologous regions of the X and the Y chromosome.3) The length of the synaptonemal complex segments remains unchanged from early diakinesis until metaphase I. The mean number of segments at early-mid diakinesis amounts to 62. At late diakinesis the segments are eliminated and replaced by chromatin bridges, the eliminated segments forming small polycomplexes. By metaphase I these polycomplexes are shed from the bivalents. 5) A comparison between the chiasma distribution as seen in the light microscope and that of crossovers or synaptonemal complex segments at mid-late diplotene reveal that chiasmata occupy more distal positions. 6) It is proposed that the pattern of elimination of the synaptonemal complexes, at diplotene, reflects differences in their resistance towards degradation along the bivalent arms, regions of high probability for crossing over being less susceptible to breakdown. The segments which are preserved through early and mid diakinesis are assumed to have gained additional resistance as a consequence of crossing over in that region.Springer-Verlag 0105-1938/83/0048/0415/$08.40

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“…The total complement length of the nuclei amounted to 213 and 206 ~tm, which is about the same as the mean complement length of 198/am measured at late (stage 7) pachytene (9).…”

Section: Early Diplotenesupporting

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Early Diplotenementioning

confidence: 99%

See 2 more Smart Citations

Human meiosis VII. Chiasma formation in human spermatocytes

Holm

Rasmussen

1983

Carlsberg Res. Commun.

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“…Previous EM studies have shown that in rat spermatocytes, all coils are left-handed as observed here, while in Rheo discolor, a dicot, all coils are righthanded (Moens 1972(Moens , 1978, consistent with the idea that coiling and its handedness is an intrinsic property of the meiotic chromosome after synapsis. In some organisms such as budding yeast (Moens 1969;Byers and Goetsch 1975;Zickler 1977;Moses 1979;Holm and Rasmussen 1983) handedness appears to be random, raising the possibility that SC structure and/or the synapsed homologs may assume multiple states in these cells.…”

Section: Discussionmentioning

confidence: 99%

Interlock Formation and Coiling of Meiotic Chromosome Axes During Synapsis

et al. 2009

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The meiotic prophase chromosome has a unique architecture. At the onset of leptotene, the replicated sister chromatids are organized along an axial element. During zygotene, as homologous chromosomes pair and synapse, a synaptonemal complex forms via the assembly of a transverse element between the two axial elements. However, due to the limitations of light and electron microscopy, little is known about chromatin organization with respect to the chromosome axes and about the spatial progression of synapsis in three dimensions. Three-dimensional structured illumination microscopy (3D-SIM) is a new method of superresolution optical microscopy that overcomes the 200-nm diffraction limit of conventional light microscopy and reaches a lateral resolution of at least 100 nm. Using 3D-SIM and antibodies against a cohesin protein (AFD1/REC8), we resolved clearly the two axes that form the lateral elements of the synaptonemal complex. The axes are coiled around each other as a left-handed helix, and AFD1 showed a bilaterally symmetrical pattern on the paired axes. Using the immunostaining of the axial element component (ASY1/HOP1) to find unsynapsed regions, entangled chromosomes can be easily detected. At the late zygotene/early pachytene transition, about one-third of the nuclei retained unsynapsed regions and 78% of these unsynapsed axes were associated with interlocks. By late pachytene, no interlocks remain, suggesting that interlock resolution may be an important and rate-limiting step to complete synapsis. Since interlocks are potentially deleterious if left unresolved, possible mechanisms for their resolution are discussed in this article.

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Diter von Wettstein and The Meiotic Program of Pairing and Recombination

Zickler¹

2020

Methods in Molecular Biology

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Human meiosis V. Substages of pachytene in human spermatogenesis

Cited by 24 publications

References 18 publications

Human meiosis VII. Chiasma formation in human spermatocytes

Human meiosis VII. Chiasma formation in human spermatocytes

Interlock Formation and Coiling of Meiotic Chromosome Axes During Synapsis

Diter von Wettstein and The Meiotic Program of Pairing and Recombination

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