Fern test is due to:

Ans. is b, i.e. Presence of NaCl under estrogenic effectRef: Shaw 15th/ed, p215* Fern test is for documenting ovulation.* Procedure: A specimen of cervical mucus is obtained and is spread on a clean glass slide and allowed to dry. It is then viewed under the low power microscope.* Result and interpretation: Under the influence of estrogen on Day l2-Day 14 cervical mucus shows characteristic pattern of fern formation. The ferning is due to the presence of sodium chloride in the mucus secreted under estrogen effect.* After ovulation on Day 21-23, ferning disappears because protein content increases and Sodium chloride decreases under the effect of progesterone.* Disappearance of ferning after ovulation and if previously present is presumptive evidence of corpus luteum activity.