Thermal convection counter streaming sedimentation method for controlling the sex of mammalian offspring

• US 4,067,965 A
• Filed: 12/17/1975
• Issued: 01/10/1978
• Est. Priority Date: 11/22/1974
• Status: Expired due to Term

• Current Assignee: Bhattacharya Bhairab C and Bhattacharya Manju
• Original Assignee: Bhairab C. Bhattacharya
• Inventors: Bhattacharya, Bhairab C.
• Primary Examiner(s): Miles, Tim R.
• Assistant Examiner(s): Hill, Ralph J.
• Application Number:
  US05/641,501
• Time in Patent Office: 755 Days
• Field of Search: 209/11, 209/158-161, 209/173, 209/208, 209/209, 209/1, 209/2, 209/111.7, 209/10, 128/1 R, 195/1.8, 195/1.7, 424/85, 424/105
• US Class Current: 424/561
• CPC Class Codes: A61K 35/52 Sperm; Prostate; Seminal fluid; Leydig cells of testes
• CPC Class Codes: B03B 13/02 using optical effects
• CPC Class Codes: B03B 5/28 by sink-float separation
• CPC Class Codes: B03B 5/623 Upward current classifiers

Abstract

A method and apparatus for controlling the sex of mammalian offspring through separation of X-chromosome female producing sperm and Y-chromosome male producing sperm. The separation is accomplished by producing a thermal convection counter stream within a sedimentation column containing a universal medium with sperm suspended therein, and subsequently allowing the two sperm populations to sediment into different fractions according to different densities. The positive and negative geotaxis thus applied to the sperm facilitate a more efficient separation than has been previously obtained. The apparatus used to accomplish this separation includes means for producing a temperature differential between axial and peripheral portions of the medium contained in the sedimentation column thus creating the necessary thermal convection counter stream, and may also comprise a laser capable of scanning the length of the column and laser detecting means to determine the distribution of sperm produced within the medium.

Claims

1. A method of controlling the sex of mammalian offspring comprising the steps of:

mixing fresh sperm with a liquid suspending medium;

providing a temperature differential between two portions of the liquid suspending medium to create, by thermal convection, counterflowing streams of medium in which sperm of different densities are carried at different rates whereby a fraction predominating in sperm having X-chromosomes separates from a fraction predominating in sperm having Y chromosomes, the temperature of the medium being sufficiently low that the motility of the sperm does not substantially interfere with the separation process; and

introducing a selected fraction into a female according to the desired sex of the anticipated offspring.

2. A method of separating sperm cells of differing densities from semen comprising the steps of:

mixing semen with a liquid suspending medium of a substantially uniform density;

immobilizing the sperm by cooling the mixture;

applying both positive and negative buoyant forces to the sperm by circulating the liquid medium in counterflowing streams whereby more dense sperm attain a different level in the liquid medium than less dense sperm; and

withdrawing a fraction of the medium containing the desired sperm.

3. A method as recited in claim 2 wherein said more dense sperm are X-chromosome containing sperm, and said less dense sperm are Y-chromosome containing sperm.

4. A method as recited in claim 2 further comprising the step of applying the positive and negative buoyant forces by creating a temperature differential between portions of the mixture of sperm and medium in order to circulate the sperm by thermally produced convection.

5. A method as recited in claim 2 further comprising the step of centrifuging the fraction withdrawn to further purify the desired sperm.

6. A method as recited in claim 2 wherein said medium comprises a mixture of glycine, α

-aminopropionic acid and egg yolk in amounts effective in aqueous solution to extend the life of said semen.

7. A method of separating mammalian sperm according to phenotypical differences related to normal and abnormal genotypes comprising the steps of:

mixing fresh semen with a liquid suspending medium; and

providing a temperature differential between two portions of the liquid suspending medium to create, by thermal convection, counterflowing streams of medium in which sperm of differing densities are carried at different rates, whereby the sperm is separated according to differing sperm densities into three fractions, a first fraction containing substantially all X-sperm of normal genotype, a second fraction containing substantially all Y-sperm of a normal genotype, and a third fraction containing both X and Y-sperm carrying defective genes, the temperature of the medium being sufficiently low that the motility of the sperm does not substantially interfere with the separation process, and withdrawing a selected sperm fraction.

8. A method as recited in claim 7 wherein said sperm are human sperm.

9. A method as recited in claim 7 further comprising the steps of:

mixing at least one separated fraction with a solution of from 5 percent to 20 percent glycerol; and

freezing the mixture in liquid nitrogen.

10. A method of separating sperm cells of differing densities from semen comprising the steps of:

mixing semen with a liquid suspending medium of a substantially uniform density which is less than that of said sperm cells;

immobilizing the sperm by cooling the mixture;

applying both positive and negative buoyant forces to the sperm by circulating the liquid medium in counterflowing streams whereby more dense sperm cells attain a different level in the liquid medium than less dense sperm cells;

permitting the medium to come to rest and allowing the sperm to further separate by gravitational sedimentation after the medium is at rest; and

withdrawing a fraction of the medium containing the desired sperm cells.