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Regulation of Reproduction by Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
The Graafian follicle has a cavity filled with follicular fluid (FF), which contains proteins, steroids, polysaccharides, metabolites, reactive oxygen species (ROS), and antioxidants. These molecules modulate oocyte maturation and protect the follicular cells from physical or oxidative damage. The egg is surrounded by granulosa cells and is enclosed by a basement membrane, theca interna and theca externa cells (Figure 10.12A). Theca cells provide androgen precursors to the granulosa cells, which produce estrogen by aromatization. During ovulation, an oocyte surrounded by cumulus cells is released by the actions of proteolytic enzymes such as plasmin, collagenase, and metalloproteinases as well as by the decrease in gap junctions. The empty follicle is then transformed into an estrogen- and progesterone-producing corpus luteum.
Reproductive System and Mammary Gland
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Justin D. Vidal, Charles E. Wood, Karyn Colman, Katharine M. Whitney, Dianne M. Creasy
The smallest follicles, the primordial follicles, are generally located in the outer portion of the cortex and consist of a small oocyte, arrested at the dictyate stage of meiosis I, encircled by a single layer of flattened, pre-granulosa cells and an outer basal lamina. The factors maintaining the primordial follicles in their arrested state of development are not well understood. During each estrous cycle, a small cohort of primordial follicles is “activated” and begins to enlarge as primary follicles; growth of the oocytes is initiated and the pre-granulosa cells become cuboidal, begin to display receptors for FSH, and start to proliferate. This continued growth results in secondary follicles, which have two or more layers of granulosa cells that encircle the enlarging oocyte. A thick coat of glycoproteins (the zona pellucida) separates the oocyte and adjacent granulosa cells (Wassarman et al. 1999). In response to factors released by the growing follicle, elongated cells recruited from the surrounding stroma form a sheath, the theca, outside of the follicular basement membrane (Magoffin 2005). Those cells nearest the follicular basement membrane, the theca interna, exhibit ultrastructural features of steroid-secreting cells consistent with their role in androgen production. The outermost thecal cells, the theca externa, in contrast are a loosely organized band of non-steroidogenic cells with ultrastructural features of fibroblasts and smooth muscle cells (Magoffin 2005; O’Shea 1981; Young and McNeilly 2010).
Normal conception
Published in David M. Luesley, Mark D. Kilby, Obstetrics & Gynaecology, 2016
The granulosa cell layer is separated from the stromal cells by a basement membrane called the basal lamina (lamina basalis). The surrounding stromal cells differentiate into concentric layers designated as the theca interna (closest to the basal lamina) and the theca externa (the outer portion). As the follicle develops, the theca cells develop LH receptors, leading to LH-stimulated production of androgens, which form the substrate for the production of oestrogen in the granulosa cell layer.
From a circle to a sphere: the ultrasound imaging of ovarian follicle with 2D and 3D technology
Published in Gynecological Endocrinology, 2019
Claudia Re, Mario Mignini Renzini, Amelia Rodriguez, Mariabeatrice Dal Canto, Matteo Buccheri, Sandro Sacchi, Silvia Bartolucci, Rubens Fadini, Antonio La Marca
Primordial follicles are quiescent until a balance between the growing and apoptotic factors promotes the exit from a quiescent status. The age related depletion of primordial follicles occurs as a result of two processes: atresia and entry in the growth phase: until the age of 30, the loss of primordial follicles is due to atresia, after, this loss is due to the entrance in the growth phase. The activation of primordial to primary follicles includes some changes in granulose cells (proliferation and differentiation) and the zona pellucida appearance so that the oocyte is covered and separated from granulosa cells by a glycoprotein polymer capsule. When transforming into secondary follicles, the external layer cells that covered the outer layer of the follicle, become theca externa and theca interna, following a cyto-differentiation. Finally, the formation of a fluid-filled cavity, adjacent to the oocyte and called antrum, defines the antral or tertiary follicle.
Chronic cholestasis is associated with hypogonadism and premature ovarian failure in adult rats (cholestasis causes ovarian hypogonadism)
Published in Ultrastructural Pathology, 2018
Transmission electron microscopy: Ultrastructural assessment revealed that the ovaries of Sham-operated rats showed no morphological defects. The ovarian surface epithelium consisted of a single layer of cuboidal cells resting on a basal lamina. These cells contained apical microvilli, numerous mitochondria, and large oval and indented nuclei (Figure 4a). Early antral follicles had distinct structural components including the theca externa, theca interna, granulosa cells, and an oocyte. The thecal cells were relatively thin, displaying flattened cells that had elongated spindle-shaped nuclei (Figure 4b). Granulosa cells were arranged in several layers. The basal layer was composed of tall cells resting on a basal lamina (Figure 4b). Other granulosa cells appeared cuboidal with abundant mitochondria, relatively thin cytoplasm and centrally located, ovoid in shape but often indented, euchromatic nucleus (Figure 4c). The inner layer of granulosa cells has thick prolongations that penetrate a smooth and relatively wide zona pellucida. The membrane of the oocyte showed numerous microvilli also penetrating the zona pellucida (Figure 4d). The ooplasm was populated with loosely clustered organelles. Mitochondria appear round or oval, rather dark with small numbers of shelf-like cristae. Cytoplasmic lamellae and electron-lucent vesicular bodies were dispersed throughout the cytoplasm (Figure 4e).
Estimation of silver nanoparticles effect on the reproductive health of female Wistar rats
Published in Egyptian Journal of Basic and Applied Sciences, 2022
Yara Mohamed, Abdel-Wahab El Ghareeb, Fawzy Ali Attaby, Heba Ali Abd El-Rahman
The histology of the control group shows well-developed follicles, normal stromal cells, and well-developed corpus luteal. The preovulatory follicle showed typical oocyte and euchromatin nucleus morphology, surrounded by typical zona pellucida and several layers of granulosa cells resting on the basement membrane. Theca interna and theca externa are developed (Figure 3).