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GAMETOGENESIS

The starting of the individual member of the human race is the fusion of the seed from his father and that from his mother to form one entity. To be able of such fusion these seeds or gametes have to mature. Maturation of both ovum and sperm involves a two-step division called meiotic division. In the first step the gamete divides into two cells each containing one half of the chromosome set, so that instead of the normal number of chromosomes, forty six in all other cells of the human body, the gamete contains only twenty three. In the second step of meiosis each cell gives rise to two cells each containing in its nucleus twenty three chromosomes, forr each chromosome replicates by tission and aquisition of genetic material in order to give two chromosomes. Mature gametes theretore are unique in containing only a half-set or the haploid number of twenty three chromosomes in contradistinction to all the other cells of the body which contain the diploid number of forty six chromosomes to be tound in normal human beings.

Of our torty six chromosomes, two in particular are concerned with determining the sex of the individual, and these are called the sex chromosomes. In the human temale these two are similar and each is called an X chromosome, so that the sex chromosome complement of the normal human female is called xx. In the male however, only one sex chromosome is X, which is naturally derived from his mother, but the other is a small chromosome called y, which is derived from the tather and which is responsible for inducing the primitive sex glands in the early embryo so that they take the direction of becoming testicles: the sex glands in the male.

The sex chromosome complement of the normal human male is expressed as xY. The remaining twenty two pairs of chromosomes are concerned with other body functions and are called the autosomes. The total normal chromosome complement can therefore be expressed as 46, XX, for females and 46, xy for males.

During maturation of the gametes therefore, a mature ovum will contain twenty three chromosomes always including one X plus twcnty two autosomes. This is not the same in sperm, for of the xy complement the X will go to one sperm and the y to another. In the sperm population therefore there will be X bearing sperms and y bearing sperms in equal numbers. If an X bearing sperm happens to fertilize the ovum, the ensuing cell, called the fertilized ovum, will have a chromosome complement of 46, XX and the baby is female. If the fertilizing sperm is y bearing, the fertilized ovum will have the complement of 46, XY and therefore a male.

The deciding factor in establishing the sex of the baby is therefore the type of the fertilizing sperm. The knowledge of this fact is fairly recent in human history , and its discovery had to await tremendous advances that culminated in our present ability to discern the chromosomes and explore their role. It is therefore eye-catching to find in the Quran the subtle reference to the role of the seminal factor in determining sex. The Quran reads:

"Does man expect to be left without purpose? Was he not a drop of ejaculated semen later to become a sticky clot subject to fashioning and proportioning (by God) and of which (God) made the two sexes: male and female?" (75:36-39) , 'That He did create in pairs male and female from a drop of semen as it is ejaculated." (53:45-46)

Another reference the Quran makes is to the site of development of the sex glands. These are the ovaries in the female and the testicles in the male, which will later on subserve the function of providing the corresponding gametes and a number of supportive hormones. At the beginning the sex glands are indiscriminate in both sexes, and are formed of a matrix of mesenchymal tissue forming on either side of the back-bone in the upper part of the abdominal cavity, to which migrate and settle the germinal cells from the primitive gut, later to become ova or sperms. It is later on during development that these sex glands are pulled down to occupy a I new position in the body, the ovaries stopping in the pelvis and the testicles f continuing to descend until they come out of the abdominal cavity and the rest in the pouch (scrotum). The original site of the sex glands has been revealed by advances in Embryology, a relatively recent science, and yet the Quran refers to this fact in the verses:

"Let Man look from what he is created. He is created from jetting water emanating from between the ribs and the backbone. (86:5-7)