Scientific history is replete with attempts to manipulate mammalian sex ratios. A longstanding objective of the reproductive physiologists has been to separate X-bearing and Y-bearing spermatozoa so that insemination of fractions would lead to off-springs o of known sex. There have been many claims of success, and certainly the sex ratio has periodically been displaced from approximately 50:50 males to females. However no methodology has yet yielded a predictable, repeatable and significant shift in the sex ratio, nor at present are there rational grounds for supposing that this can be achieved ( Hunter).
In lower chordates and ratites of course there has been proven history of possibility of altering the sex ratio ( Bull et al.). There have been instances of changing the sex ratios in ratites and lower chordates with the help of certain chemicals such as estradiol, 17 beta and dihydrotestosterone etc. discussed and disclosed in American patent numbers 5,20,280 and5,377,618. There have been instances of TDSD ( Temperature Dependant Sexual Determination ) in lizards , crocodiles and other related species ( Bull et al ) . This may be attributed to the lack of organized chromatin in these animals but in mammals which have a much organized chromatin such instances are not reported
There have been generally three courses applied to achieve the shift in sex ratio in mammals.
A) First were the attempts to produce sexed semen. Such attempts can be listed as
Gordon, M.J.1958.The control of sex. Scientific Am. 199:87-94.
Bhattacharya et al.1966.Nature.211:863.
Meistrich, M.L.1982.Prspects of sexing mammalian sperm in R.P.Amann and G.E.Seidel, Jr. (eds.) Colorado University Associated Press.
Corson et al,1984.Fertil.Steril.42.756.
There was a mention in the U.S. patent office in patent number 4999283 that H-Y antigen could be used to bind and hence separate Y bearing spermatozoa. The main difficulty in above techniques is that experimental attempts have been hampered by the lack of laboratory tests to evaluate the degree of sperm separation ( Hafez ). Also, there has been the problem that spermatozoa are haploid cells possessing only half the usual number of chromosomes for the species , there is no evidence that haploid- as distinct from diploid-cells express their genetic constitution in surface characteristics . This being the case , it is difficult to imagine how chemical, electrical or bio-physical separation of X or Y spermatozoa might be obtained (Hunter). Other problems associated with these techniques were poor conception rate due to decrease in concentration and functional activity of spermatozoa, genetic tempering , complexity of these techniques, expensiveness, difficulty in handling , transport etc. of resultant sexed semen if any ? and embryos so obtained ? etc.
B) Secondly there were attempts to use certain compounds, anti-sera, globulins etc. to achieve a shift in the sex ratio . These attempts included.
Beernik etal, 1984.Presented at the annual meeting of American Fertility Society.
Barrat and Leger.1979.J.Gynecol.Obstet.Biol.Reprod.(Paris).8,332.
Sampson et al, 1983.Fertil.Steril.40,481.
Mitra and Chowdhury,1990.Abstr.iin Animal Breed.Abstrs.58(4):No.2354. etc.
The sex ratio shift by these methods was not much and it continued to fluctuate slightly up or down the usual sex ratio. The resultant efficacy of these methods was poor and could not be replicated in further experimentations and it was never fit to put it to a practical use on larger and practical scales.
C) Thirdly there were attempts to alter the physiological and functional environment in the vagina and related parts of sexual tract in female animals. This approach had attracted many takers and right from the days of Schroeder it has been a subject of attraction to the reproductive physiologists . Changes in the normal sex ratio of animals have been attributed to such conditions as season , diet, stress, -pH of the female tract, ageing or irradiation of gametes, and age of the parents. Although there is much disagreement on the extent of the effect of these factors, many attempts at controlling sex ratio have been based on them. A number of attempts made about 1940, were based on the theory that vaginal –pH controlled sex. An acid condition was supposed to effect the sperm such that a preponderance of females would result; an alkaline condition would theoretically produce males. Although some publicity gaining claims were made, conclusive evidence was not found in careful scientific investigations ( Salisbury). Hence, these techniques based on changing –pH in the vaginal tract were destined to rejection and desertion even before the end of the first half of the last century ( Lawrence) . A lot of water has flown down the bridge since then but the fact remains that these techniques could never be revived, proved or followed in careful, logical and systematic scientific experiments and evaluations after that (McPhee and Eaton ) . Diasio and Glass studied the effect of –pH on sperm motility by allowing sperm migration through capillaries containing media of differential-pH, but showed motility of Y bearing sperm were not affected by the -pH of the media. There was no scope left for such adventures and only some childish or foolish wild hints and imaginations remained to exist on the scientific horizon regarding production of sexed off-springs in mammals by manipulating –pH value in the vaginal tract of female animals. In 1960, Shettles first distinguished two morphological types of sperm, the large oval headed sperm correlating with the X chromosome, and the smaller rounded headed sperm correlating with the Y chromosome. He proposed that abstinence prior to ovulation with intercourse occurring at ovulation only, alkaline baking soda vaginal douching, female orgasm, deep penile penetration and preferably vaginal penetration from the rear, will assist the smaller faster Y sperm, while no prior abstinence, intercourse two to three days before ovulation, acid white vinegar vaginal douching, no female orgasm, shallow penetration in the missionary position will favor larger X bearing sperm. The problem with his approach was that two many confounding variables were used in his study , and further large scale testing could not produce the same results ( To et al ).
The prominent methodology involved was to change the –pH levels in the vaginal and related parts of reproductive tracts of female animals. Even there has been a mention as a vague and wild hint in American patent number 4,336,801, that a change in –pH of vagina and related parts of genital tracts of certain mammals can effect the sex of the off-spring but nothing has been corroborated by the concrete practical and experimental data as tested on real animals in clinical and field trials in careful scientific studies. This has found a mention merely as a wild guess. There has been certain mentions of some methodologies regarding certain equipments, douche-nozzles, ovulation monitors etc. in patents, 4336801, 3749089, 4159718 and 3219525 which could be used to administer materials in mammalian vaginas with ease and convenience. But the fact remains that the scientific community the world over is not a taker of this idea any more. Another fact that there can be at least a thousand or tens of thousands if not a million chemicals that can be employed to produce a change in the –pH of vagina or other parts of female genital tract of mammals. To come to a logical conclusion as to which is the most suitable compound that will surely produce a certain sexed off-spring by changing the –pH in vagina and related parts will require the employment of at least tens of thousands of scientific experimental studies and that will require the entire life spans of many thousands of scientists ,all brilliant in the field of mammalian reproductive physiology to arrive at a logical conclusion that such and such experimentation with a given chemical can yield a verifiable, predictable and repeatable methodology ( Hunter).
Given all said and done, this is the most common knowledge on earth that manipulation of mammalian sex ratio is not a reality and still remains a mirage on the horizon ( RV Short as quoted by Hunter). The entire human history and thinking is definitely bound to have a sea change when there will be a single pin pointing of a particular compound that will produce a definite and predictable change in the sex of the mammalian off-spring either by vaginal or otherwise administration and the present research is of this category. This is a different criteria and fact that this research in no way employs or intends to employ a route of administration other than the oral one. This is entirely different from the earlier vaginal routes that produced vague and ambiguous results which now stand no where and could never be replicated in the subsequent scientific studies or at the most they were only imaginative hints , the types of which exist as a running mention in U.S. patents number 4336801 discussed above. The present research is only a practical and field study based on a set of experiments that were really conducted by the person reporting this in the U.S. patent office by way of following application and this is only the result of actual clinical experimental trials and the outcome is reported as such and nothing has been concealed or exaggerated and the reference is drawn to a single compound , sodium ethanoate which was actually used to produce female off- springs in cows, then buffaloes and then as inspired by the success, further experiments were conducted on other mammals as reported in the present application.