Histological description of the Seminiferous Epithelium cycle in the common shrew(Sorex Araneus L.)

Garagna, Silvia; Zuccotti, Maurizio; Searle, Jeremy B.; Redi, Carlo Alberto

doi:10.1080/11250008909355654

Cited by 13 publications

(11 citation statements)

References 6 publications

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“…3. Section through a seminiferous tubule at stage V o f the epithelium cycle (Garagna et al, 1989a) from a chain Vll-forming complex heterozygous shrew. Note the large num bers o f round sperm atids (St) and fully formed sperm atozoa (Sz).…”

Section: Resultsmentioning

confidence: 99%

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Male common shrews (Sorex araneus) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Mercer

Wallace

Searle

1992

Cytogenet Genome Res

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Two chromosomal races of common shrews (Sorex araneus) were crossed in captivity to generate chain VH-forming complex Robertsonian heterozygotes. Meiosis and gametogenesis were studied in three male hybrids. Regular chain VII configurations were observed at both pachytene and diakinesis/metaphase I, although in many pachytene spreads the chain configuration was incomplete (the basis of this peculiarity is unknown). From metaphase II counts, the frequency of anaphase I nondisjunction in the complex heterozygotes was estimated to be 13 %. Germ-cell death in the chain VII-forming complex heterozygotes was 22 % greater than it was in controls, but this difference is unlikely to have greatly influenced the capacity of the heterozygotes to sire offspring. Thus, the fecundity of these complex heterozygous common shrews would probably have been only slightly reduced relative to homozygous or simple heterozygous shrews. These results call into question the generality of speciation models based on the presumed sterility of complex heterozygotes.

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Section: Resultsmentioning

confidence: 99%

“…3). An impression was gained, however, that there were fewer spermatozoa in the seminiferous tubule crosssections at epithelial stage V (Garagna et al, 1989a). compared with the number of spermatozoa observed in controls at the same epithelial stage.…”

Section: Germ-cell Deathmentioning

confidence: 99%

Male common shrews (Sorex araneus) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Mercer

Wallace

Searle

1992

Cytogenet Genome Res

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“…On the basis of these diameters the mean tubular crosssectional area for each male was calculated. The preparations stained by PAS were used to count round spermatids (sd) and primary spermatocytes (sc) in cross-sections at stages II, VI and VIII of the 10-stage seminiferous ephitelium cycle (Garagna et al 1989a). Primary sc at stage VIII were scored only, because an elongation of sd made them difficult to count at this stage of spermiogenesis.…”

Section: Histological Preparationsmentioning

confidence: 99%

Fertility in the male common shrews, Sorex araneus, from the extremely narrow hybrid zone between chromosome races

Jadwiszczak

Banaszek

2006

Mammalian Biology

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“…Even more clearcut is the evidence provided by Garagna et al (1989b) concerning the differential process of the ovary in mice bearing complex structural heterozygosities. They compared the number of oocytes per ovary in 18-day embryos and 20-day-old mice carrying complex structural heterozygosities, and their respective homozygous controls.…”

Section: Hybrid Negative Heterosismentioning

confidence: 99%

Chromosomes and microevolutionary processes

Capanna

Redi

1994

Bollettino di zoologia

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The role of chromosomal rearrangement in microevolutionary processes is discussed, considering numerous aspects of the complex mechanisms of chromosomal speciation. The different degrees of chromosome-derived subfertility, a consequence of the different kinds of structural heterozygosities in the inter-racial hybrids, are discussed with reference to the effectiveness of the postmating reproductive barrier. A «non meiotic» view of the reproductive fitness of the Robertsonian heterozygotes and homozygotes is proposed. It is based on the possibility that Robertsonian fusion, and chromosomal structural rearrangement in general, may alter the internal topography of interphasic nucleus. Consequent upon any such change would be an alteration in the collocation of the gene clusters in the nuclear domains programmed for their regular function. It is claimed that these considerations explain the selective advantage that the new homokaryotype must have over the nonrearranged type for the new chromosomal variant to be fixed and maintained within a panmyctic population. Also discussed are the role of the demographic factors involved in chromosomal speciation and the molecular mechanisms responsible for the chromosomal rearrangement. An alloperipatric model of chromosomal speciation seems not to conflict with the «geographical» speciation principle of Mayr, and to be fully justified in terms of biological theory.

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Histological description of the Seminiferous Epithelium cycle in the common shrew(Sorex Araneus L.)

Cited by 13 publications

References 6 publications

Male common shrews (<i>Sorex araneus</i>) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Male common shrews (<i>Sorex araneus</i>) with long meiotic chain configurations can be fertile: implications for chromosomal models of speciation

Fertility in the male common shrews, Sorex araneus, from the extremely narrow hybrid zone between chromosome races

Chromosomes and microevolutionary processes

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