Spontaneous rhythmic contractions were observed in 14 follicles after the application of small amounts of tension. Contractions, involving marked increases in tone, sometimes associated with onset or increase of rhythmic contractility, were elicited by epinephrine, norepinephrine, acetyl choline, carbachol, and prostaglandin F₂. Relaxation was induced by isoproterenol, histamine, 5-hydroxytryptamine, and prostaglandin E₂. Responses to oxytocin were variable. The effects of -adrenergic drugs were blocked by tolazoline and phentolamine, those of isoproterenol by propranolol, and those of cholinergic drugs by atropine.

Contractile responses were demonstrated at all stages of the estrous cycle as recognized by histological examination of corpora lutea, and appeared stronger at late than at early or midstages of the cycle. The strongest contractions recorded were in large luteinized follicles.

These results demonstrate that contractility is a property of the walls of ovarian follicles in sheep, and indicate a range of responses to pharmacological agents.