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 an
ovum, the sex of the developing fetus will be male. If
the ovum is fertilized by a sperm carrying X
chromosome, the result will be a female embryo. On
each side of the embryo, a primitive gonad arises from
the genital ridge2. The gonad develops a cortex and a
medulla. Until the sixth week of development, these
structures are identical in both sexes. In case of XY
chromosomes, the medulla develops into a testis
during the 7-8 weeks and the cortex regresses1. Leydig
cells appear next and small amount of testosterone is
secreted for growing male sex organs of fetus2. While
in case of XX chromosomes, the cortex develops into
an ovary and the medulla regresses. The embryonic
ovary does not secrete hormones. Each of the
embryonic ovaries is initially populated by about 1000
to 2000 primordial germ cells which through rapid
proliferation give rise in each ovary to about three
million oocytes1. This number of oocyte is reduced
through cell death to 1 million at birth and each of
them is surrounded by a single layer of flattened
epithelial cells, granulosa cells. The ovum remains
inactive and is suspended in the prophase stage of
meiotic division till puberty1. After puberty in
response to GnRH from hypothalamic pituitary glands
produce gonadotrophic hormones. The responsibility
of imprinting the fetal hypothalamus to produce a male
or female pattern of gonadotrophin release has been
ascribed to testosterone
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