Endometrial response to IVF hormonal manipulation: comparative analysis of menopausal, down regulated and natural cycles

Abstract

Background: Uterine luminal epithelial cell response to different hormonal strategies was examined to determine commonality when an endometrium attains a receptive, stimulated, morphological profile that may lead to successful implantation.

Methods: Endometrial biopsies from 3 cohorts of patients were compared. The tissue samples taken from these patients were categorized into 8 different groups according to their baseline and the hormone regime used.

Results: Pre-treatment natural cycle tissue was variable in appearance. Downregulation with a GnRH analogue tissue appeared menopausal in character. HRT after downregulation resulted in tissue uniformity. HRT in menopause resulted in a 'lush' epithelial surface. HST in the natural cycle improved the morphology with significant difference in secretion between the two regimes examined.

Conclusions: Down regulation plus HRT standardized surface appearance but tissue response is significantly different from the natural cycle, natural cycle plus HRT or menopause plus HRT. HRT in menopause reinstates tissue to a state similar to a natural cycle but significantly different from a natural cycle plus HST. HST with a natural cycle is similar to tissue from the natural cycle but significant differences reflect the influence of the particular hormones present (at any point) within the cycle.

Figure 1

Representation of the treatment timelines, regimes used and biopsy days.

Figure 2

SEM of uterine epithelium at D4P from different women during a natural cycle. (A) Several patients showed a well stimulated, secretory epithelium consistent with Day 4P or 5P, displaying developing or fully developed uterodomes. Scale bar = 5 μm. (B) In contrast some patients showed an epithelium that was suboptimal and representative of early proliferative epithelium. Microvillous cells were flat and sparsely covered with low, blebbed microvilli. Ciliated cells are infrequent and the cilia low and numerically reduced. Scale bar = 10 μm. (C) Tissue appearance varied from areas of small polygonally shaped microvillous cells with well developed microvilli, cell protrusion and secretory droplets, to areas of flattened or protruding epithelium with obvious cell borders between large pleiomorphic cells. Scale bar = 10 μm.

Figure 3

SEM at D4P showing gland variability between samples from women during a natural cycle. (A) The glands are raised on circular hillocks with large, slit-like openings and demonstrates an out-of-phase glandular appearance indicative of E₂ stimulation alone or insufficient P₄ exposure. Scale bar = 0.1 mm. (B) Epithelium of normal appearance displaying numerous flattened glands with small, rounded openings. Scale bar = 0.1 mm.

Figure 4

SEM of tissue from a patient undergoing downregulation (Group 3). (A) The epithelial response to pituitary down-regulation with GnRH is similar to that of an unstimulated epithelium. The microvillous cells are undemarcated and flat with sparsely distributed low or blebbed microvilli. Apical cell membrane is exposed (asterisk), apical defects (AP) and cell porosity (CP) apparent. Groups of cilia are still apparent but cilia number is reduced exposing bulging cellular apices (arrows). Scale bar = 5 μm. (B) The epithelial response in the same patient as (A) after pituitary down-regulation followed by HRT. A well stimulated, mature secretory phase morphology suggestive of D5P was observed. Mid to long, dense microvilli were observed on protruding cells, and there was an abundance of well ciliated cells, secretory droplets and fully developed uterodomes (U). Scale bar = 5 μm.

Figure 5

SEM of postmenopausal tissue. (A) Tissue heterogeneity is pronounced with inconsistencies in cell size and shape. Arrows denote cell separation. Scale bar = 0.1 mm. (B) Microvillous cells are sparsely covered with very low or blebbed microvilli. Denuded or bald cells (asterisk) are frequently seen. Scale bar = 10 μm. (C) Atrophic epithelium displays flat, pleiomorphic cells with obvious cell borders and single cilium (arrows). Scale bar = 10 μm.

Figure 6

SEM of postmenopausal tissue after HRT. (A) Microvillous cells are uniformly small and polygonally shaped, covered with dense microvilli and showing apical cell protrusion. Ciliated cells (c) are numerous. Scale bar = 10 μm. (B) Fully developed uterodomes (u) were observed in most patients at biopsy D6P. Scale bar = 10 μm.