Superovulation and embryo culture in vitro following treatment with ultra-pure follicle-stimulating hormone in cats.

Oestrus was induced in nine prepubertal and nine adult cats using three different doses (2.5, 10 and 30 iu divided into five daily doses) of an ultra-pure preparation of porcine follicle-stimulating hormone (FSH) without any luteinizing hormone activity. After 5 days of treatment, ovulation was induced by two daily injections of human chorionic gonadotrophin and the cats were mated. One week later (on day 12) the ovaries were examined for the number of unovulated follicles and ovulation sites. In eight of the nine prepubertal cats the ovaries had 20-90 large follicles per cat and only two cats ovulated (8-9 corpora lutea). All adults responded and ovulated. Adult cats had 3-40 large follicles and 6-35 corpora lutea each. In each group, ovarian response (and ovulation rate) was related to the dose of FSH. The 79 embryos that could be recovered at days 11-13 after the onset of treatment, using a new technique, were assessed; those of good quality were cultured until complete degeneration. One eight-cell embryo was cultured for 12 days through the blastocyst to the gastrula-somite stage. With the highest FSH dosage there was increased degeneration of embryos. This may be associated with the high oestrogen concentrations that were produced during oestrus induction. Potential culture of feline embryos up to the advanced blastocyst stage in modified phosphate-buffered saline supplemented with fetal calf serum was demonstrated.