Establishing a Mouse Model of Thin Endometrium

Summary

This article describes a detailed protocol for producing a reliable and reproducible thin endometrium with a very low mortality rate and minimal intrauterine adhesions by injecting 95% ethanol into the mouse uterus within 1-3 min.

Abstract

Thin endometrium (TE) has been widely recognized as a critical cause of infertility. However, the pathogenesis of TE remains unclear, and satisfactory treatment options are still urgently needed. Several animal models of TE have been developed, but the mouse model involving abdominal surgery and injection of 95% ethanol presents a formidable challenge due to the high mortality rate and risk of intrauterine adhesions if not performed correctly. Here, we describe a detailed protocol that produces reliable and reproducible TE with a very low mortality rate and minimal intrauterine adhesions by injecting 95% ethanol into the mouse uterus with varying infusion times. The results showed that all of the mice successfully developed TE with infusion times ranging from 1-3 min, characterized by a typical reduction in endometrial thickness and the number of glands, as well as excessive endometrial fibrosis. These findings suggest that this mouse model is suitable for studying thin endometrium and can serve as a platform for developing future TE treatments.

Introduction

Thin endometrium (TE) is a serious condition in obstetrics and gynecology that often affects women of childbearing age. TE is diagnosed when the endometrium thickness measures less than 7 mm on an ultrasound scan, accompanied by a normal uterine cavity, and is closely associated with pregnancy failure^1,2. It is estimated that approximately 1.5%-9.1% of women undergoing in vitro fertilization (IVF) treatment will experience TE, making it a growing challenge in reproductive medicine^3,4,5. The most common causes....

Protocol

This study was approved by the Institutional Animal Care and Use Committee of Shenzhen Zhongshan Obstetrics & Gynecology Hospital (formerly Shenzhen Zhongshan Urology Hospital), where all animal experiments were conducted. Female C57BL/6 mice (age 6-8 weeks, weight 18-20 g) were used in this study. All animals were housed in a specific pathogen-free (SPF) environment in the same room and acclimatized for one week before the experiments in a room without specific pathogens at (22 ± 1) °C under a 12-h light/d.......

Discussion

TE is characterized by insufficient cell proliferation and dysfunctional cells, closely linked to infertility, recurrent miscarriage, and placental abnormalities^2,3. Unfortunately, there is currently no effective therapy for TE. Animal models play a crucial role in studying this condition. Between 2014 and 2024, rats were used as model organisms in 16.4% of 208,000 studies (34,200 studies) and mice in 22.7% (47,300 studies). The increasing use of mice in experime.......

Materials

Name	Company	Catalog Number	Comments
Anesthesia Machine	RWD Life Science	R530	Mobile inhalation anesthesia machine for small animals
0.9% saline	Hubei Kelun Pharmaceutical	C230817A2	10 mL, medical injection
75% ethanol	LIRCON	6303060031	500 mL, disinfectant reagent
95% ethanol	Guangzhou Chemical Reagent Factory	64-17-5	500 mL, chemical reagent
Absorbable sutures	Jinhuan Medical	CR537	Thickness: 5-0; Length: 90 cm
Aqueous ammonia	MilliporeSigma	1336-21-6	1000 mL, chemical reagent
Automatic Tissue Processor	Leica	TP1020	100 embedding boxes can be processed at one time
C57BL/6 mice	Experimental Animal Center of Southern Medical University
Eosin-Y	BASO	BA4024	1000 mL, used for the staining of paraffin sections, frozen sections, etc
Haematoxylin	BASO	BA4041	1000 mL, used for the staining of paraffin sections, frozen sections, etc
HALO Image Analysis Platform	Indica labs		The instrument features ease-of-use and scalability, powerful analytical capabilities, and the fastest processing speed
Hemostatic clamps	HUAYON	18-5021	1.8 cm in total length with 0.7 cm jaw
Hemostatic forceps	HUAYON	18-5020	10 cm in total length
HistoCore Rotary Microtome	Leica	149BIO000C1	Slice thickness ranges from 1 to 60 μm
Indorphor	ADF	1005	500 mL, disinfectant reagent
Isoflurane	RWD Life Science	R510-22-10	100 mL, active ingredient 100% isoflurane
Masson's trichrome staining	SOLARBIO	G1340	7 × 100 mL for 100 tests
Microscope slide	Gene Tech	GT100511	Length: 75 cm; Width: 25 cm
Modular Tissue Embedding Center	Leica	EG1150 C	The instrument contains a cold stage and a heated paraffin distribution module, providing flexibility for the embedding work
Natural resin	SAKURA	4770	Resin-coated film, Suitable for histology staining
Olympus SLIDEVIEW VS200	PANOVUE	VS200	The instrument captures high-quality virtual slide images and enables advanced quantitative image analysis
Paraformaldehyde fix solution	Servicebio	G1011	500 mL, universal tissue fixative (neutral)
Surgical forceps	HUAYON	18-1300	2.2 mm straight, 12.5 cm wide
Surgical scissors	HUAYON	18-0110	10 cm, stainless steel surgical scissors
Syringe	Kindly	60017031	1 mL, disposable sterile syringe with needle
Tissue cassettes	CITOTEST	80106-1100-16	White; flow-through slots; 0ne-piece integral lid; labeling areas are located on three sides
Tissue-Tek Prisma Plus	SAKURA	DRS-Prisma-P-JCS	The processing capacity is 60 slides at one time
Xylene	Guangdong Guanghua Sci-Tech	1330-20-7	1000 mL, organic solvent