ABSTRACT
Gonads Gonads are the bilateral primary sex organs, testis or ovary. The rest of the reproductive apparatus consists of secondary sex organs. Gonads develop in the genital ridge, on the medial aspect of the urogenital (U-G) ridge. As the gonad enlarges it becomes demarcated by a genital groove from the lateral nephrogenic cord (Figure 1). The gonads have a dual reproductive function:
• Secretion of male or female sex hormones by endocrine cells originating in the mesodermal com ponent of the primitive gonad
• Production of haploid gametes, spermatozoa or ova, originating in the gonocytes, the endodermal com ponent of the gonad.
