The Hogben test procedure consisted of injecting a sample of women's urine into the skin on the back of the frog, specifically into the dorsal lymph sac.[17] Around 12 hours later, results could be seen. If the woman was pregnant, then the frog would be ovulating, and a small cluster of eggs could be seen at the rear end of the frog. Interestingly, the same could be observed in the male species of Xenopus laevis as well, and they were seen to produce sperm upon injection of a pregnant woman's urine.[18] This mechanism is due to the pituitary hormone human chorionic gonadotropin (hCG), which is present only in a pregnant woman's urine. If the woman is not pregnant, no sperm or egg would be produced from the male or female frog respectively.