<prompt> Spinnbarkeit refers to?Cervical mucusUterine gland thicknessCervical os appearanceProliferation of breast alveoli  <response>: Ans. a Cervical mucusRef.-.Ganong25th ed. 402 The cervical mucus is thinnest at time of ovulation and its elasticity or spinnbarkeit increases such that by mid- cycle one drop can be stretched into a long, thin thread that may be 8-12cm or more in length. It dries on a slide in an arborizing fern like pattern. After ovulation it becomes thick and fails to form the fern pattern. 