This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tests of Ovulation, Subject name: Gynaecology & Obstetrics
The earliest morphological evidence of ovulation is: 
Select and explain. 
A. Pseudo stratification, B. Basal vacuolation, C. Decrease in glycogen content, D. Predecidual reaction
B: Basal vacuolation
Answer: B: Basal vacuolation 
Explanation: Subnuclear (basal) vacuolation : Ist HPE evidence of ovulation ( evidence of progesterone secretion ) Endometrial biopsy Invasive test EBX: HPE (Formalin) and AFB for TB( Normal saline ) Done usually 2-4 days before expected date of menses(D24 - D26) Not done Post menses Secretory endometrium( Progesterone acts) on EBxtells cycle is ovulatory Proliferative endometrium: anovulatory Early secretory Subnuclear vacuolation (Ist HPE evidence of progesterone secretion) Seen on D16 of cycle Nuclei of glands gone up Stromal edema Late secretory Toous/ coiled glands All secretions in lumen of gland Cork screw glands( on D20 of cycle) Max stromal edema seen around D22of cycle) HPE of Proliferative endometrium Pseudostratification Long tubular glands