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Differentiation of X and Y chromosomes in sperm
CORRESPONDENCE
Differentiation of X and Y chromosomes in sperm
Reply to Dr. Glass To the Editors:
Investigations with electron microscopy have shown two types of normal human sperm with respect to head size and shape. Also, phase contrast microscopy has been confirmatory of the two distinct sperm populations. Moreover, scanning electron microscopy has revealed the same categories of cytologically normal human sperm. 1 A sex ratio at conception as high as 160: 100 (male: female) has been cited. 2 It has been stated that, "This may arise from the greater number, greater rate of locomotion, and smaller head mass of the Y chromosome-containing sperm," and "When tested in a capillary tube filled with ovulation cervical mucus over a distance of 1 foot, the small headed sperm invariably wins the race. 3 Rohde and colleagues, 4 • 5 in studies of progressive sperm motility in the cervical mucus of women, found a fraction that was rich in Y-bearing sperm in the frontal zone of sperm migration, identified by the quinacrine staining method. Using an in vitro penetration test, Kaiser and associates6 reported similar results. Roberts' 7 observations on gravitational separation of motile sperm substantiated that the Y sperm have greater motility and less mass. Ericsson and co-workers8 reported isolated fractions rich in Y-bearing human sperm, with the use of progressive sperm motility in bovine serum albumin solutions of various densities, in which the fluorochrome quinacrine stain and fluorescence microscopy were employed. With the above information, the scanning electron photomicrographs of human sperm depicted by Ericsson and co-workers in the fractions reported rich in Y sperm, and the fact that all research associates agree unequivocally that these fractions, indeed, contained the smaller-headed sperm in confirmation of our earlier observations, the head size was related to the presence of the Y chromosome; Ericsson and coworkers made no reference to this relationship. Photographs of intact, morphologically normal human sperm taken by means of conventional, phase contrast, and electron microscopy will not reflect the nuclear differences resulting from the fact that the Y chromosome is smaller than the X chromosome 1• a. 4 • 7• 8 ; instead, that the X-chromosome sperm contain significantly more cytoplasm in the head is shown. Concerning the ratio of X: Y sperm in any specimen, since no one has shown with quinacrine dihydrochloride
To the Editors:
In the "Correspondence" section (AM. J. 0BSTET. GYNECOL. 124: 441, 1976), Dr. Landrum B. Shettles stated that Ericsson and associates/ using quinacrine staining of the Y chromosome, found that smallerheaded sperm contain the Y chromosome. This statement is not found in the article cited by Shettles, and at no time has Ericsson2 made such a claim. Pearson and associates3 did find that X sperm have a 7 per cent larger surface area than do Y sperm. However, Evans4 could not demonstrate differences in nuclear area measurements between sperm with and without a Y chromosome. Shettles has also suggested that two thirds of sperm are of a smaller-headed type and that these contain a Y chromosome. Contrary to this claim are findings by a number of groups working with the quinacrine stain, indicating that the Y chromosome is present in slightly less than 50 per cent of sperm.t. 5 _ 7
Robert H. Glass, M.D. Department of Obstetrics and Gynecology University of California, San Francisco San Francisco, California 9414 3
REFERENCES I. Ericsson, R. J., Langevin, C. H., and Nishino, M.: Isolation
2. 3.
4.
5. 6. 7.
of fractions rich in human Y sperm, Nature 246: 42.1, 1973. Ericsson, R. J.: Personal communication. Pearson, P. L., Geraedts, J. P. M., and Pawlowitski, I. H.: Chromosomal studies on human male gametes, in Boue, A., and Thibault, C., editors: Proceedings of the Symposium Chromosomal Errors in Relation to Reproductive Failure, Paris, September, 1973, Paris, 1973, Centre International de L'Enfance, pp. 219-227. Evans, H. J.: Properties of human X andY sperm, in Beatty, R. A., and Gluecksohn-Waelsch, S., editors: Proceedings of the International Symposium on the Genetics of the Spermatozoon, Edinburgh, August, 1972, Copenhagen, 1972, Bogtrykkeriet Forum, pp. 144-159. Barlow, P., and Vosa, C. G.: TheY chromosome in human spermatozoa, Nature 226: 961, 1970. Diasio, R. B., and Glass, R. H.: Effects of pH on the migration of X andY sperm, Fertil. Steril. 22: 303, 1971. Kaiser, R., Citoler, P., and Broer, K. H.: Relative increase in Y chromatin bearing spermatozoa after in vitro penetration into human cervical mucus, Int. Res. Commun. Syst. 2: llOO, 1974.
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Differentiation of X and Y chromosomes in sperm
Reply to Dr. Glass To the Editors:
Investigations with electron microscopy have shown two types of normal human sperm with respect to head size and shape. Also, phase contrast microscopy has been confirmatory of the two distinct sperm populations. Moreover, scanning electron microscopy has revealed the same categories of cytologically normal human sperm. 1 A sex ratio at conception as high as 160: 100 (male: female) has been cited. 2 It has been stated that, "This may arise from the greater number, greater rate of locomotion, and smaller head mass of the Y chromosome-containing sperm," and "When tested in a capillary tube filled with ovulation cervical mucus over a distance of 1 foot, the small headed sperm invariably wins the race. 3 Rohde and colleagues, 4 • 5 in studies of progressive sperm motility in the cervical mucus of women, found a fraction that was rich in Y-bearing sperm in the frontal zone of sperm migration, identified by the quinacrine staining method. Using an in vitro penetration test, Kaiser and associates6 reported similar results. Roberts' 7 observations on gravitational separation of motile sperm substantiated that the Y sperm have greater motility and less mass. Ericsson and co-workers8 reported isolated fractions rich in Y-bearing human sperm, with the use of progressive sperm motility in bovine serum albumin solutions of various densities, in which the fluorochrome quinacrine stain and fluorescence microscopy were employed. With the above information, the scanning electron photomicrographs of human sperm depicted by Ericsson and co-workers in the fractions reported rich in Y sperm, and the fact that all research associates agree unequivocally that these fractions, indeed, contained the smaller-headed sperm in confirmation of our earlier observations, the head size was related to the presence of the Y chromosome; Ericsson and coworkers made no reference to this relationship. Photographs of intact, morphologically normal human sperm taken by means of conventional, phase contrast, and electron microscopy will not reflect the nuclear differences resulting from the fact that the Y chromosome is smaller than the X chromosome 1• a. 4 • 7• 8 ; instead, that the X-chromosome sperm contain significantly more cytoplasm in the head is shown. Concerning the ratio of X: Y sperm in any specimen, since no one has shown with quinacrine dihydrochloride
To the Editors:
In the "Correspondence" section (AM. J. 0BSTET. GYNECOL. 124: 441, 1976), Dr. Landrum B. Shettles stated that Ericsson and associates/ using quinacrine staining of the Y chromosome, found that smallerheaded sperm contain the Y chromosome. This statement is not found in the article cited by Shettles, and at no time has Ericsson2 made such a claim. Pearson and associates3 did find that X sperm have a 7 per cent larger surface area than do Y sperm. However, Evans4 could not demonstrate differences in nuclear area measurements between sperm with and without a Y chromosome. Shettles has also suggested that two thirds of sperm are of a smaller-headed type and that these contain a Y chromosome. Contrary to this claim are findings by a number of groups working with the quinacrine stain, indicating that the Y chromosome is present in slightly less than 50 per cent of sperm.t. 5 _ 7
Robert H. Glass, M.D. Department of Obstetrics and Gynecology University of California, San Francisco San Francisco, California 9414 3
REFERENCES I. Ericsson, R. J., Langevin, C. H., and Nishino, M.: Isolation
2. 3.
4.
5. 6. 7.
of fractions rich in human Y sperm, Nature 246: 42.1, 1973. Ericsson, R. J.: Personal communication. Pearson, P. L., Geraedts, J. P. M., and Pawlowitski, I. H.: Chromosomal studies on human male gametes, in Boue, A., and Thibault, C., editors: Proceedings of the Symposium Chromosomal Errors in Relation to Reproductive Failure, Paris, September, 1973, Paris, 1973, Centre International de L'Enfance, pp. 219-227. Evans, H. J.: Properties of human X andY sperm, in Beatty, R. A., and Gluecksohn-Waelsch, S., editors: Proceedings of the International Symposium on the Genetics of the Spermatozoon, Edinburgh, August, 1972, Copenhagen, 1972, Bogtrykkeriet Forum, pp. 144-159. Barlow, P., and Vosa, C. G.: TheY chromosome in human spermatozoa, Nature 226: 961, 1970. Diasio, R. B., and Glass, R. H.: Effects of pH on the migration of X andY sperm, Fertil. Steril. 22: 303, 1971. Kaiser, R., Citoler, P., and Broer, K. H.: Relative increase in Y chromatin bearing spermatozoa after in vitro penetration into human cervical mucus, Int. Res. Commun. Syst. 2: llOO, 1974.
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