Nuclear Morphology of Human Spermatozoa

Shettles, Landrum B.

doi:10.1038/186648a0

Cited by 48 publications

(23 citation statements)

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“…After attempting to count the chromosomes, he concluded that the smaller heads contain the Y and the larger the X chromosome. There were no intermediate types 1. The following year he reiterated these findings, adding that smaller headed spermatozoa can migrate more rapidly and fertilise the egg more often in the distal part of the tube 2…”

mentioning

confidence: 84%

“…EDITOR—The widely held idea that spermatozoa bearing the Y chromosome (Y sperm) swim faster than those bearing the X chromosome (X sperm) seems to have originated from Shettles's work in 1960, using phase-contrast microscopy 1. He claimed to have observed “two distinct populations” of spermatozoa 1.…”

mentioning

confidence: 99%

“…He claimed to have observed “two distinct populations” of spermatozoa 1. After attempting to count the chromosomes, he concluded that the smaller heads contain the Y and the larger the X chromosome.…”

mentioning

confidence: 99%

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Entrenched misinformation about X and Y sperm

Grant

2006

BMJ

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mentioning

confidence: 84%

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confidence: 99%

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Entrenched misinformation about X and Y sperm

Grant

2006

BMJ

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“…Debates surrounding the physical differences between X‐ and Y‐CBS have long captivated biologists. Initially recorded by Shettles in 1960, differences in spermatozoa head size and swim speed have been of most interest. Initially, these differences were widely accepted; however, after follow‐up research provided contentious results, the idea lost traction (e.g., Ref.…”

Section: Sexual Dimorphism During Early Developmentmentioning

confidence: 99%

Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals

Cameron

Edwards

Parsley

2016

Annals of the New York Academy of Sciences

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Sex allocation theory predicts biased offspring sex ratios in relation to local conditions if they would maximize parental lifetime reproductive return. In mammals, the extent of the birth sex bias is often unpredictable and inconsistent, leading some to question its evolutionary significance. For facultative adjustment of sex ratios to occur, males and females would need to be detectably different from an early developmental stage, but classic sexual dimorphism arises from hormonal influences after gonadal development. Recent advances in our understanding of early, pregonadal sexual dimorphism, however, indicate high levels of dimorphism in gene expression, caused by chromosomal rather than hormonal differences. Here, we discuss how such dimorphism would interact with and link previously hypothesized mechanisms for sex-ratio adjustment. These differences between males and females are sufficient for offspring sex both to be detectable to parents and to provide selectable cues for biasing sex ratios from the earliest stages. We suggest ways in which future research could use the advances in our understanding of sexually dimorphic developmental physiology to test the evolutionary significance of sex allocation in mammals. Such an approach would advance our understanding of sex allocation and could be applied to other taxa.

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“…Other differences include the size of spermatozoa i.e. X sperm is larger than Y sperm (Cui and Matthews, 1993;Cui, 1997;Moruzzi, 1979), motility (motility is reported to be higher in Y chromosome than X chromosome bearing spermatozoa) (Shettles, 1960), surface charges in sperm (X sperm has a negative charge and Y sperm has a positive charge) (Kiddy and Hafs, 1971) and cell surface antigens (Hoppe and Koo, 1984). Among these differential characteristics, differences…”

Section: Basic Principles Of Sex-selectionmentioning

confidence: 99%

Sexing of Spermatozoa in Farm Animals: a Mini Review

Prakash¹

2014

Adv. Anim. Vet. Sci.

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Livestock farmers always have a wish for producing young ones of desired sex. Among the several techniques available, use of sexed semen for artificial insemination is recognized as more pragmatic and easy way to pre -select the sex of the offspring. Selective use of sexed semen in breeding will not only increase the genetic progress from the daughter -dam path but would also help in producing good male germplasm from elite bulls for future breeding. Several attempts have been made, elsewhere in the globe, to develop methods that efficiently separate bovine semen into fractions containing higher concentrations of X -or Y -bearing sperm. These technologies include sex specific antibodies, centrifugation and flow cytometry. Of these attempts, the only method proven to be commercially viable is flow cytometry. However, sorting pressure, speed, electrical deviation, laser radiation all leads to membrane alteration and pre -capacitation like changes in the sorted sperm leading to reduced fertility. Despite these limitations, production of sexed semen usually followed by cryopreservation is being used commercially for cattle production. Development of the instrument for increasing the sorting rate and also purity of sorting without affecting the viability and fertility is still an active area of research. The aim of this review is to update the readers with the recent developments in sexing of spermatozoa with special reference to farm animals.All copyrights reserved to Nexus® academic publishers

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Nuclear Morphology of Human Spermatozoa

Cited by 48 publications

References 1 publication

Entrenched misinformation about X and Y sperm

Entrenched misinformation about X and Y sperm

Developmental sexual dimorphism and the evolution of mechanisms for adjustment of sex ratios in mammals

Sexing of Spermatozoa in Farm Animals: a Mini Review

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