请用更地道、更科学、更书面化的英语表达如下内容：EEOs and ESCs were collected respectively and combined either with or without HUVECs in a hydrogel matrix For 30 μl of hydrogel 100 EEOs 5 × 104 ESCs and 15 × 104 HUVECs were u

Ectopic endometrial organoids (EEOs) and embryonic stem cells (ESCs) were separately collected and then combined with or without human umbilical vein endothelial cells (HUVECs) in a hydrogel matrix. A total of 100 EEOs, 5 × 104 ESCs, and 15 × 104 HUVECs were used for every 30 μl of hydrogel. In order to promote the formation of blood vessel networks from HUVECs, fibrinogen was introduced into Matrigel to create the hydrogel matrix. Different ratios of fibrinogen and Matrigel (1:9, 5:5, and 9:1, referred to as F1M9, F5M5, and F9M1) were employed. When fibrinogen was present in the hydrogel, thrombin was added to initiate the coagulation process.

For static culture, 30 μl of hydrogel with cells was placed in a 48-well plate and cultured in ExM medium. To establish the endometrium-on-a-chip (eCHIP) culture system, 30 μl of hydrogel with cells was placed in an insert of the μ-Slide lII 3D Perfusion ibiTreat plate (80376, IBIDI, USA) and incubated at 37 °C for 20 minutes to allow the hydrogel to solidify. Subsequently, the eCHIP was perfused with ExM/ECM medium.