Related Experiment Video
Updated: Jun 21, 2026
Human Egg Maturity Assessment and Its Clinical Application
Published on: August 19, 2019
Analysis of spindle characteristics and embryo quality in mice stimulated with letrozole using Polscope imaging
Ashalatha Ganesh1, Ratna Chattopadhyay, K Narendra Babu
1School of Medical Science and Technology, Indian Institute of Technology, Kharagpur, India.
Objective:
To explore the effect of letrozole as an ovulation inducing agent on oocyte and embryo quality in mice model.
Design:
Prospective study.
Setting:
Institute of Reproductive Medicine, Kolkata, India.
Animal(S):
Sixty-nine sexually mature female Swiss Albino mice 6-7 weeks old.
Intervention(S):
Metaphase II (MII) oocytes from two groups of mice, one group injected with letrozole and the other with rFSH.
Main Outcome Measure(S):
Number of MII oocytes, number of oocytes with meiotic spindle (MS), different angles of MS relative to the polar body (PB), spindle characteristics, and fertilization outcome.
Result(S):
The MS was present in 84% and 71.2% of the oocytes in the letrozole and rFSH group, respectively. In the letrozole group, 73% of the oocytes had a 0 degrees spindle position compared with 35.7% in the rFSH group. With letrozole, 19% of the oocytes had 0 degrees > MS < 90 degrees and 8% had MS >90 degrees , compared with 46.1% oocytes with 0 degrees > MS < 90 degrees and 18.2% with MS >90 degrees with rFSH. Mean spindle area retardance, spindle dimensions, and 4-8-cell embryo formation rate were significantly higher with letrozole compared with rFSH. Two-cell and blastocyst formation rates were similar in both groups.
Conclusion(S):
Robust birefringent spindles were obtained in mice on superovulation with letrozole. Letrozole does not appear to increase the risk of spindle assembly and preimplantation developmental arrest in mouse oocytes.
