The Comparative Physiology of Gamete Populations

Cohen, Jack

doi:10.1016/b978-0-12-011504-4.50011-5

Cited by 34 publications

(21 citation statements)

References 204 publications

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“…Samples (20 µ ) of each flush were taken for counting, using the fixed-drop method described by Cohen (1971), after suitable dilution with PBS, fixed in acetic-alcohol and stained with methyl blue-eosin (Casarett, 1953 Immunofluorescence staining was carried out using a procedure similar to that used by Cohen & Werrett (1975 …”

Section: Sperm Recoveriesmentioning

confidence: 99%

“…Immunoglobulins of fertile female mammals have been found to coat the acrosomes of normal ejaculated spermatozoa (Edwards, 1969;Cohen, 1971), probably via the Fc end of the molecule (Cohen, 1978;Allen & Bourne, 1978). Chang (1947) described the deleterious effect of fresh, but not heat-inactivated, serum on rabbit spermatozoa and Bedford (1969) described pathological changes associated with this effect.…”

Section: Introductionmentioning

confidence: 99%

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Sperm populations in the female genital tract of the rabbit

Cohen¹,

Tyler²

1980

Reproduction

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Section: Sperm Recoveriesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sperm populations in the female genital tract of the rabbit

Cohen¹,

Tyler²

1980

Reproduction

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“…Data from these two groups are considered here, sacrificing information from a rotifer and a mite which both have achiasmate spermatogenesis. The insects and mammals provided markedly different regression coefficients according to the figures provided by Cohen (1971Cohen ( , 1973, but subsequent corrections have reduced this heterogeneity to an acceptable level. Fig.…”

Section: Argumentmentioning

confidence: 99%

“…1, black stars). Table 2 shows the figures from which these estimates were derived (Cohen, 1971); in the absence of any experimental details, these figures are highly questionable. The count of 70 zygotes appears to be a mistake, for it is virtually identical to the number of eggs laid in a single pod (Norris, 1952).…”

Section: Argumentmentioning

confidence: 99%

Chiasmata have no effect on fertility

Wallace

1974

Heredity

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“…The massive degeneration of oocytes in mammals (atresia), has previously been considered a meiotic redundancy (Cohen, 1969); the female Drosophila was seen to fit as well. Unfortunately, although oocyte atresia is known in fishes, echinoderms, and annelids as well as mammals, I have no chiasma data for those females for which I have atresia figures (data in Cohen, 1971). Also eggs have four haploid sets, effectively, which slightly modifies the story because of the possibility of" meiotic drive ".…”

mentioning

confidence: 99%

Cross-overs, sperm redundancy and their close association

Cohen

1973

Heredity

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SUMMARYNumbers of cbiasmata in the production of each gamete are closely related to the proportion of gametes which fail to function (r = 081 for 24 species).Gamete redundancy and chiasma frequency fail to correlate with chromosome number, DNA weight/nucleus, or the weight or age of the animal at puberty, as closely as with each other. Implications and corollaries are considered, and it is concluded that most gametes are functionless by-products of a necessarily faulty production system. IN 1967 I suggested that a faulty process associated with chiasmata (crossingovers) might account for the large excess of gametes, particularly sperms. This might have gone undetected by geneticists because all zygotes examined (usually as adults) would show no evidence of such faults, if gametes with these faults never fertilise. So production as well as utilisation errors might lead to wastage of the majority of gametes (Cohen, 1967).Comparison of the logarithm of sperm" redundancy " with the number of chiasmata involved in the production of each sperm, for a variety of species, could test this idea. As chiasma number increases linearly, so the proportion of non-faulty sperms would fall exponentially, and so the total number required for each fertilisation would rise exponentially. In 1967 I had only located mean chiasma frequency (C) and sperm redundancy (R) for seven species. One unpublished chiasma frequency and a preliminary sperm number investigation gave nine points and a correlation coefficient r = 090.Since then I have found many more figures, and the picture they produce is a very significant one ( fig. 1). There are 33 points for 24 animal species, and correlation coefficient r = 0.87 (and Spearman rank correlation is 0.81) if different workers with the same species are considered separately, or 08 1 (and 0.77) if they are considered together as a mean for the species. For 28 degrees of freedom P <000001 (some points are not independent) and for 22 degrees of freedom P<0O001. There is therefore no question that mean chiasma frequency and sperm redundancy are very highly associated.If this association does reflect causality, if a chiasma-associated phenomenon requires multiplicity of sperms because only a fraction" work ", then the regression of Log R on C gives more information. The slope of the association is a measure of the increase of Log R for one cross-over, and suggests that a third (0.29) of chiasmata give unacceptable products. The height of the line, as judged by the Y intercept, suggests that utilisation problems on average require about fifty "good" sperms to be offered for one to fertilise. So for organisms with high C, like man, fig. 1 grains per seedfmean chiasma frequency for Prunus avium. X and Y are total egg production/mean chiasma frequency for Crasso.trea ("R" and C, Longwell and Stiles, 1968) and Mtilus ("R" and C, Ahmed and Sparks, 1970). there would be about a hundred of these in a normal human ejaculate.Correlations do not necessarily reflect direct causality; both R and C might be depende...

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The Comparative Physiology of Gamete Populations

Cited by 34 publications

References 204 publications

Sperm populations in the female genital tract of the rabbit

Sperm populations in the female genital tract of the rabbit

Chiasmata have no effect on fertility

Cross-overs, sperm redundancy and their close association

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