Fig. 1

SEM and TEM microphotographs of the endometrium under the influence of different concentrations of vitamin D during the implantation window. SEM and TEM microphotographs of vitamin D deficient (a and b), insufficient (c and d), and replete (e and f) patients. (a) Pinopodes not yet fully formed, ×3000 magnification. (c) Pinopodes in the developmental stage with abundant expression, × 3000 magnification. (e) Clusters of mature pinopodes with abundant expression, × 3000 magnification. b Intracytoplasmic organelles abundant with a few vacuoles; The nucleus is irregularly shaped and locally concave. Heterochromatin increases and aggregates can be seen around the nuclear envelope (examples are indicated by black arrowheads); The mitochondria are abundant, some are dropsical and dilated (reddish brown); The rough endoplasmic reticulum is swollen and dilated (blue); The Golgi apparatus (orange); Intracellular autophagy are less distributed (purple). d Intracytoplasmic organelles are abundant with a few vacuoles; The nucleus is irregularly shaped and locally concave without heterochromatin (black); The mitochondria are abundant without obvious edema or distention (reddish brown); The rough endoplasmic reticulum (blue); Intracellular autophagy is obviously increased (purple). The lysosomal (green). f Intracytoplasmic organelles are abundant; The nucleus is irregularly shaped and some are accompanied by nuclear division. Heterochromatin levels are elevated and aggregated around the nuclear envelope (black); The mitochondria are abundant, some are dropsical and dilated (reddish); The rough endoplasmic reticulum is swollen and dilated (blue); Intracellular autophagy is obviously increased (purple)