Analysis of spindle characteristics and embryo quality in mice stimulated with letrozole using Polscope imaging.
OBJECTIVE
To explore the effect of letrozole as an ovulation inducing agent on oocyte and embryo quality in mice model.


METHODS
Prospective study.


METHODS
Institute of Reproductive Medicine, Kolkata, India.


METHODS
Sixty-nine sexually mature female Swiss Albino mice 6-7 weeks old.


METHODS
Metaphase II (MII) oocytes from two groups of mice, one group injected with letrozole and the other with rFSH.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Ganesh
Ashalatha
A
School of Medical Science and Technology, Indian Institute of Technology, Kharagpur, India.
Chattopadhyay
Ratna
R
Narendra Babu
K
K
Chakravarty
Baidyanath
B
Chaudhury
Koel
K
D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D046149:Embryo Culture Techniques; D005260:Female; D005300:Fertility Agents, Female / Q000009:adverse effects / Q000494:pharmacology*; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D000077289:Letrozole; D008297:Male; D051379:Mice; D008859:Microscopy, Polarization; D009570:Nitriles / Q000009:adverse effects / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects* / Q000648:ultrastructure; D010060:Ovulation / Q000187:drug effects*; D010062:Ovulation Induction / Q000009:adverse effects / Q000379:methods*; D011994:Recombinant Proteins / Q000494:pharmacology; D008941:Spindle Apparatus / Q000187:drug effects* / Q000648:ultrastructure; D013997:Time Factors; D014230:Triazoles / Q000009:adverse effects / Q000494:pharmacology*
D005300:Fertility Agents, Female; D009570:Nitriles; D011994:Recombinant Proteins; D014230:Triazoles; D000077289:Letrozole; D005640:Follicle Stimulating Hormone