Related Experiment Video
Updated: Jan 15, 2026

Generation of Multicellular Human Primary Endometrial Organoids
Published on: October 4, 2019
Ultrastructural changes in human endometrium at different phases of the menstrual cycle and their functional
Abstract:
A review of the ultrastructure of normal human endometrium at different phases of the cycle is presented. The structural changes are correlated to the functional implications in the light of the recent knowledge on the functioning of cell organelles. Relatively undifferentiated cells of the beginning of the menstrual phase become functionally matured, proliferate and later degenerate. The appearance of the nucleolar channel system during the secretory phase coincides with the rise of progesterone level and facilitates the nucleocytoplasmic exchange. The secretion of the endometrial glands consists of glycogen, glycoproteins, lipids and mucopolysaccharides. Large autophagic vacuoles (giant lysosomes) digest various cell components at the end of the cycle. All the lamina functionalis of the endometrium is not shed, a part of it is regressed by focal death (autophagic vacuoles) and by total death (apoptosis) of individual cells.
Related Concept Videos
The Menstrual Cycle
The menstrual phase occurs from days 1 to 5 and involves the shedding of the stratum functionalis, as a...
Secretory Phase
Following ovulation, the corpus luteum, a temporary endocrine structure, produces progesterone and estrogens. These hormones stimulate the growth and coiling of endometrial...
Menses Phase
When fertilization does not occur, the corpus luteum deteriorates, causing a significant drop in the levels of estrogen and progesterone in the body. This hormonal decrease triggers the release of prostaglandins, which cause the uterine...
Hormonal Regulation of the Menstrual Cycle
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH...
Proliferative Phase
Notably, the stratum basale, the basal layer of the endometrium, including the basal parts of the uterine glands, remains unaffected by menstruation. Stem cells in this layer undergo mitosis, regenerating the stratum functionalis and thickening the...
Histology of the Uterus
The endometrium is the...

