ENDOCRINE EVENTS AND LIFE STAGES OF WOMEN
Abstract
The sex of every baby is determined at the time ofconception1. If a "Y" carrying sperm fertilizes anovum, the sex of the developing fetus will be male. Ifthe ovum is fertilized by a sperm carrying Xchromosome, the result will be a female embryo. Oneach side of the embryo, a primitive gonad arises fromthe genital ridge2. The gonad develops a cortex and amedulla. Until the sixth week of development, thesestructures are identical in both sexes. In case of XYchromosomes, the medulla develops into a testisduring the 7-8 weeks and the cortex regresses1. Leydigcells appear next and small amount of testosterone issecreted for growing male sex organs of fetus2. Whilein case of XX chromosomes, the cortex develops intoan ovary and the medulla regresses. The embryonicovary does not secrete hormones. Each of theembryonic ovaries is initially populated by about 1000to 2000 primordial germ cells which through rapidproliferation give rise in each ovary to about threemillion oocytes1. This number of oocyte is reducedthrough cell death to 1 million at birth and each ofthem is surrounded by a single layer of flattenedepithelial cells, granulosa cells. The ovum remainsinactive and is suspended in the prophase stage ofmeiotic division till puberty1. After puberty inresponse to GnRH from hypothalamic pituitary glandsproduce gonadotrophic hormones. The responsibilityof imprinting the fetal hypothalamus to produce a maleor female pattern of gonadotrophin release has beenascribed to testosteroneReferences
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