Y. Ohnami et al., THE USE OF ULTRASONOGRAPHY TO STUDY THE RESPONSES OF CYSTIC OVARIAN FOLLICLES IN COWS TO TREATMENT WITH GNRH ANALOG, Irish veterinary journal, 48(7-8), 1995, pp. 275-276
A single intramuscular injection of 200 mu g GnRH-A induced rupture of
persistent follicles in nine cows within one or two days. On four occ
asions the luteal tissue that developed at the site of rupture was not
identified by rectal palpation but in each case transrectal ultrasono
graphy revealed the doughnut image of a cystic corpus luteum and hormo
ne assay revealed that it was actively secreting normal quantities of
progesterone.