Sex Determination

Determination of individuals sex depends on the kind of sperm that unites with the ovum. Two kinds of spermatozoa are produced in equal numbers. The first contains twenty two matched chromosomes plus one x chromosome. The second contains twenty two matched chromosome plus one y chromosome. The x and y chromosomes are sex determining chromosomes. The mature ovum always contains and x chromosomes. If it is fertilized by y bearing spermatozoa, The offspring will be a buy. If it is fertilized an x bearing spermatozoa, the offspring will be a girl.

Number of offsprings

Most of humans are born singletons, multiple birth also occur in some cases. Wen a ripe ovum is fertilized by one spermatozoa, the result will be a singleton, unless the fertilized ovum (zygote) splits into or more distinct parts during the early stage cell cleavage. When this happens, the result will be identical twins, triplets, or other multiple births. If to or more Ava are released simultaneously and are fertilized by different spermatozoa, the result will be nonidentical twins, triplets or other multiple birth. Meredith has reported that 1 out of 80 births is twins 1 out of 9000 is triplets and one out of every 570000 quadruplets. There are more frequent multiple birth among blacks and fewer among Chinese, Japanese and other Mongoloid, race group than there are always whites.