At approximately day 1

Involution of the milk streak is completed. Anlage moves to a more ventral position. Crest is formed into a nodule that begins to sink into the differentiating mesenchyme.

Reference [PubMed Link]

Gusterson BA, Stein T. 2012. Human breast development. Seminars in Cell and Developmental Biology 23(5):567-573.

At approximately day 1

In the absence of fetal gonadal testosterone, the indifferant gonad develops into an ovary. Germ cells, which are located in the cortex both in and out of the sex cords, gather into large clusters.

Duration: 2 weeks

Reference [PubMed Link]

Rabinovici J, Jaffe RB. 1990. Development and regulation of growth and differentiated function in human and subhumand primate fetal gonads. Endocrine Reviews 11(4):532-557.