Template:Endometrium phases

(Determine the type or phase of the endometrium:)

In contrast, endocervical mucosa typically consists of mucinous columnar epithelium and mucinous glands. Evaluate this like a cervical biopsy or cervical cone.

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  The most superficial layer of the endometrium usually consists of a simple columnar epithelium.
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  Postmenopausal (atrophic) endometrium: Thin epithelium, and scattered glands lined by columnar cells with small inactive nuclei, supported by a dense fibrous stroma of spindle cells. (H&E stain)

The phases of endometrium through the menstrual cycle:

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  Proliferative endometrium: long curving glands (G) and some stromal edema (H&E stain)
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  Secretory endometrium: Prominent glands (G), which have a dilated lumen and an irregular outer border stretching down into the basal compartment. In the luminal (functional) layer immune cells are readily detected (most of these are likely to be macrophages and uterine natural killer (uNK) cells), as are areas of decidualised fibroblasts (DEC) close to arterioles. (H&E stain)

If you want to specify the phase by day, then it's more accurate to state it as days past ovulation where applicable, since the follicular phase may vary substantially.