Oocyte retrieval and selection
David K. Gardner, Ariel Weissman, Colin M. Howles, Zeev Shoham in Textbook of Assisted Reproductive Techniques, 2017
Cumulus cells are Graafian follicular cells that surround and nourish the oocyte during its development in the ovary. The innermost layer of cumulus cells, immediately adjacent to the ZP, is called corona radiata. Cells of the corona radiata extend their cytoplasm toward the oocyte through the ZP. Communication (either paracrine interaction or gap junction) occurs between the oocyte and the cumulus-corona cells. Such interactions allow oocyte nutrition and maturation during its preovulatory growth from the diplotene to the MII stage (102, 103). Corona radiata and cumulus cells maintain their contact with the oocyte at the time of ovulation, during a normal menstrual cycle, or after withdrawal by aspiration, in hormonally stimulated assisted reproduction cycles.
In Vitro Fertilization and Embryo Transfer
Asim Kurjak in Ultrasound and Infertility, 2020
Between 100,000 and 500,000 motile spermatosoids are added to every mature oocyte. Out of those 500,000 spermatozoa, 500 to 1000 manage to stick to the zone pellucida of the oocyte. Although in natural circumstances such a high number of spermatozoa never get into contact with a single oocyte, up to now statistics show that no significant difference between the number of triploidias resulting from in vitro program (4%) and ones spotted in early abortions following natural reproduction could be spotted (8%). To ensure fertilization, the oocyte is kept in insemination medium for not less than 16 to 18 h. Now the microscopic examination in normally fertilized ova should show male and female nuclei and two polar bodies. Sometimes, however, corona radiata cells obstruct a clear view on fertilization and, to get a view of the oocyte, cytoplasm should be removed.
Fertilization and normal embryonic and early fetal development
Hung N. Winn, Frank A. Chervenak, Roberto Romero in Clinical Maternal-Fetal Medicine Online, 2021
Already few minutes after the ovulation, oocyte is located in the ampullar part of the fallopian tube. It is surrounded by the zona pellucida. On the surface of the zona pellucida, there are few rows of the granulosa cells that make corona radiata. At the periphery of the corona radiata are left cells of cumulus oophorus. Often, these three units are called oocyte–corona–cumulus complex. Capability for the fertilization is limited: oocyte can be fertilized only 6 to 12 hours after the ovulation. Sperms are capable for fertilization 48 to 72 hours, until they are movable. Fertilization occurs in the ampullar part of the fallopian tube. The process of fertilization begins with conditioning of the spermatozoon in the male and female reproductive tracts. Thereafter, fertilization involves not only the egg itself but also the various investments that surround the egg at the time it is released from the ovary follicle. Fertilization, therefore, is not an event; it is a complex biochemical process requiring a minimum of 24 hours to complete syngamy (formation of a diploid set of chromosomes). During that process, there is no commingling of maternal and paternal chromosomes within a single nuclear membrane (pre-zygote); after this process, the paternal chromosome material is commingled (zygote). The most important activity of this new cell is the recognition of the new genome that presents the principal information center for the development of the human being and for all its further activities.
Effects of vitamin D on ovary in DHEA-treated PCOS rat model: A light and electron microscopic study
Published in Ultrastructural Pathology, 2018
Latife Seyran Çelik, Yurdun Kuyucu, Ebru Dündar Yenilmez, Abdullah Tuli, Kenan Dağlıoğlu, Ufuk Özgü Mete
In the ovaries of control rats, the ovarian medulla consisting of a fibromuscular stroma and a large number of blood vessels was seen (Figure 1A). Primordial follicles and primary follicles at different stages of development were observed in normal structure (Figure 1B). The DHEA administrated ovaries of rats showed polycystic characteristics when compared with the control. There were a great number of cystic follicles in the ovaries of DHEA group rats (Figure 1C) and these multiple dilated follicular cysts had enlarged antrum and thinner granulosa cell layers (Figure 1D). We observed that the granulosa cells became 2–3 layers or even one layer and the granulosa cells which adjacent to antrum were flattened. Beside it, there were no oocyte and corona radiata in cystic follicles and they had well-developed theca cell layer (Figure 1E). Some of the follicular cysts had macrophages in their antrum (Figure 1F). In vitamin D treated group ovaries, follicles at different stages of development, CL and atretic follicles were seen (Figure 1G, 1H). Cystic follicles are smaller and fewer in this group compared to DHEA group (Figure 1I).
Potential of thrombospondin-1 in treatment of polycystic ovary syndrome rat model: a preliminary study
Published in Gynecological Endocrinology, 2021
Mei-mei Liu, Chao Wang, Yu-hong Zhang, Rui-jing Wang, Xiu-min Lu, Pei-ling Li, Yu-xin Wang, Pi-dong Gong, Ning Liu, Ting Zhang, Ting-ting Tian
In the blank control group (Figure 3(A)), the corpus luteum and multiple follicles were shown at different developmental stages, and the follicular granulosa cells were in 8–9 layers with ordered arrangement, the radioactive crown and oocytes mainly were located in the follicles. In the control group (Figure 3(B)), the number of follicles and corpus luteum at all levels decreased, and multiple cystic dilated follicles could be observed to become vesicles, that is, empty follicles. The follicles increased in size and formed like a string. The radial crown or oocytes in the follicles disappeared, and the granular cells were in 2–3 layers with loose arrangement; the number of corpus luteum and follicles in the TSP-1 experimental group (Figure 3(C)) was between the blank control group and the control group. The follicles were slightly cystic expansion, the string follicles decreased, and corona radiata and oocytes were observed in part of follicles, the granular cells were in 6–8 layers with loose arrangement (Table 3, Figure 3). After giving TSP-1 or saline for 21 days, compared with the control group, the vessel density of the TSP-1 experimental group decreased significantly, but compared with the blank control group, the vessel density in the TSP-1 experimental group increased significantly (p < .05, Table 3).
Longitudinal Changes in the Sensorimotor Pathways of Very Preterm Infants During the First Year of Life With and Without Intervention: A Pilot Study
Published in Developmental Neurorehabilitation, 2021
Sonia Khurana, Megan E Evans, Claire E Kelly, Deanne K Thompson, Jennifer C. Burnsed, Amy D. Harper, Karen D. Hendricks-Muñoz, Mary S Shall, Richard D Stevenson, Ketaki Inamdar, Gregory Vorona, Stacey C Dusing
DTI metrics (FA and MD) and volume were calculated for five white matter regions of interest (ROIs): i) corticospinal tract (CST), ii) posterior limb of internal capsule (PLIC), iii) corona radiata (CR), iv) cerebral peduncles (CP), and v) cerebellar peduncles (CBP). In case of cerebellar peduncle we averaged superior, middle, and inferior cerebellar peduncle together to obtain one single value each for FA and MD. However, volume was derived by adding the values of all three regions together into one. The CST was chosen to be the primary region of interest based on its importance in the output of voluntary movement, as well as the extensive literature on CST dysfunction in preterm infants.25 Likewise, the PLIC is commonly used to predict the development of cerebral palsy based on the amount of myelination.26 Lastly, the corona radiata, cerebral peduncles, and cerebellar peduncles (superior, middle, and inferior) were included based on their role in motor learning and motor processing.27,28
Related Knowledge Centers
- Axon
- Cerebral Cortex
- Corticobulbar Tract
- Internal Capsule
- Neuroanatomy
- Projection Fiber
- White Matter
- Centrum Semiovale
- Corticopontine Fibers
- Corticospinal Tract