Copyright information:  information content copyright owned by Cat World expires 70 years from March 1973 at which time the information minus the research notes may be placed in the public domain.
Research Note:  Here is an article which has been partially converted for online presentation.  It is from the March/April 1974  issue of Cat World which holds the copyright for the text.  This text has not been split into separate files so that it makes for easier printing.  Question:  Is it better to allow for printing or optimize for reading and information chunking.  Note the graphics additions to visually break the text.  Note the bolding of terms and the links to other information -- which add a new original dimension to the work and enhance the information offering.

Sex Chromosomes and Sex Determination

The sex of each kitten is decided by a pair of chromosomes known as the sex chromosomes; all other chromosomes being known as autosomes. The characters inherited along with the sex chromosomes are known as sex linked or sex limited characters and those inherited irrespective of the sex chromosomes are known as autosomal characters. Sex limited characters are caused by genes that can affect only one sex because of the sex chromosome on which they are inherited or because of the physiological differences between sexes. In man there is a gene, inherited along with the Y chromosome, causing him to have hairy ears. An example of a sex linked gene in the domestic cat is red coat color (described by geneticists as orange) and an example of an autosomal character in the cat is agouti.

There are two types of sex linked chromosome -- the X chromosome and the Y chromosome. The female cat has an identical chromosome pair XX and the male has a dissimilar pair XY. All the ova produced by the female will have only one X chromosome in addition to the autosomes while all the spermatozoa produced by the male may have either an X or a Y chromosome in addition to the autosomes. In other words the female is only capable of producing eggs with an X chromosome while the male will produce equal numbers of spermatozoa carrying Y and X. If the ovum is fertilized by a spermatozoon  carrying the X chromosome then the resultant kitten will have two X chromosomes (XX) and will be a female. If, on the other hand, the ovum is fertilized by a spermatozoon carrying the Y chromosome then the resultant kitten will have one X chromosome and one Y chromosome (XY) and will be a male.