Browsing by Author "Fidan, Pinar Ayran"

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Comparative Analysis of Trophoblasts and Angiogenesis in Human Placental Compartments
(2022) Fidan, Pinar Ayran; Dagdeviren, Attila
SUMMARY: Trophoblasts perform different functions depending on their location. This study aimed to obtain structural clues about the functions of villous and extravillous trophoblasts by using light and electron microscopy. Term placenta samples were obtained from 10 healthy pregnant women following cesarean sections. Frozen sections were stained with hematoxylin-eosin, semithin sections were stained with toluidine blue and examined with a light microscope, while thin sections were contrasted using uranyl acetate-lead citrate and evaluated under an electron microscope. Fine structural features of villous trophoblasts overlapped some villous stromal cells. In addition to the usual appearance of mature capillaries in villous stroma, we demonstrated and reported maturational stages of angiogenetic sprouts in term placenta. Extravillous trophoblasts were classified according to their location: fibrinoid, chorion, trophoblastic, column, maternal vascular endothelium, or decidua. All of these trophoblasts shared some ultrastructural features but also were distinct from each other. In decidua, it was noted that the endothelial lining of some vessels was invaded by a few endovascular trophoblasts with irregular microvilli. These cells shared some ultrastructural properties with both villous trophoblasts and stromal cells. Examination showed that angiogenesis was still present in term placentas and that trophoblasts, endothelial and stromal cells have very similar properties ultrastructurally, suggesting they represent transformational forms.
Comparison of the Efficacy of Cabergoline and Bromocriptine in a Rat Model of Ovarian Hyperstimulation Syndrome
(2018) Coban, Pinar Gulsen; Oruc, Ayla Sargin; Ozaksit, M. Gulnur; Demirtas, Aysegul; Helvacioglu, Fatma; Fidan, Pinar Ayran; Sirvan, Levent; Eroglu, Semra; https://orcid.org/0000-0002-6026-0045; AAH-8887-2021; AAD-8353-2020
OBJECTIVE: To compare cabergoline and bromocriptine for their effectiveness in ovarian hyperstimulation syndrome (OHSS) and their impact on endometrial receptivity in a rat model. STUDY DESIGN: A total of 25 immature Wistar female rats were randomly assigned to 5 groups: group 1 (control), group 2 (hyperstimulated), group 3 (cabergoline), group 4 (2 mg/kg bromocriptine), and group 5 (4 mg/kg bromocriptine). Body-ovarian weights, the number of corpora lutea, and endometrial receptivity were investigated. RESULTS: Cabergoline appeared to be less effective in reduction in body weight (p = 0.042). Ovarian weight was significantly reduced by a higher dose of bromocriptine (p<0.000). The number of corpora lutea were similar. In the cabergoline group, endometrial pinopode expression was reduced. In the bromocriptine groups the presence of pinopode formation was not affected, whereas some of those displayed different structural features like dome or racket shaped of yet undetermined significance. CONCLUSION: According to our findings, bromocriptine, particularly in higher doses, might be preferred with regard to ovarian mass suppression, weight gain, and pinopode expression. Further studies assessing the efficacy and safety of different doses of bromocriptine administration in OHSS followed by clinical trials about implantation and pregnancy rates are required.
Implications for thymus growth in childhood: histogenesis of cortex and medulla
(2019) Fidan, Pinar Ayran; Kaymaz, F. Figen; Dagdeviren, Atilla; 0000-0003-3047-0305; 0000-0001-8990-8282; 30155680; ABG-5365-2020; P-2877-2014
The increase in autoimmune diseases in recent years has drawn attention back to the thymus, with new approaches to improve and/or restore immune function being investigated. As the primary lymphoid organ responsible for functional T cell development, studies on the pre-/post-natal development of this organ and T lymphocytes in human and other species are of special interest. During our screening studies we observed structures that had not been described or mentioned previously, and named them epitheliostromal sheaths. Associated with these unique structures were also small attached lobules (possibly reflecting the maturational stages of thymic lobules), which the authors consider as markers of histogenesis and the growth of the organ during early childhood; these findings are thus presented to researchers in this field. Approximately 1000 sections prepared from infantile thymic tissues of partial biopsy specimens were immunostained and examined. Specimens were taken from ten patients (with informed consent) in the age range of 4-9years who underwent surgery due to congenital cardiovascular anomalies but were otherwise normal. Digital images of interest were captured to describe them in detail. Determining the immunophenotype of the compartments in these newly developing lobules assisted us greatly in defining compartments and their growth order. In summary, our findings suggest a niche-based thymus growth mechanism during childhood. We presented our findings, hoping to provide additional insight to researchers aiming to restore thymus function in adulthood and improve its immunological functions.
Intussusceptive Growth of Vascular Bed in Human Placenta
(2019) Fidan, Pinar Ayran; Helvacioglu, Fatma; Dagdeviren, Atilla; 0000-0003-3047-0305; ABG-5365-2020
Objective: Normal embryonic and fetal development is strictly bound to maternal health and functioning placenta. Besides the invasion and differentiation of trophoblastic cell lineage; development of effective vasculature is crucial for the function of placenta. Placental vessels first arise by vasculogenesis in early development of villi and then succeeded by angiogenesis during fetal life. In the recent decades a new form of angiogenesis, "intussusceptive angiogenesis", besides classical sprouting angiogenesis is well documented. The presence of intussusception was shown at multiple organs but in placenta, in recent literature. We aimed to determine whether intussusceptive angiogenesis is present in human placenta to obtain further evidence on the development of vascular bed. Methods: The term placenta samples were obtained from 10 healthy pregnancies following caesarean sections. Tissues were processed using routine plastic embedding technique; thin sections were contrasted with uranyl acetate & lead citrate; observed and photographed by transmission electron microscope. Results: Our examinations revealed that both sprouting and intussusceptive angiogenesis is present in floating villi of term placenta. Phases of intussusception were documented in various samples. Conclusion: The presence of intussusceptive angiogenesis will help our understanding of microvascular bed remodeling during pregnancy. We believe that this new finding will help us to determine the relation of microvascular bed development in normal and abnormal placentas.
Modeling Of Human Placental Capillaries By Using A Unique 3d Reconstruction Program İnsan Plasenta Kapillerlerinin Özgün Bir Yazılımla 3 Boyutlu Modellemesi
(2023) Fidan, Pinar Ayran
Purpose: Visualization of the three-dimensional structures is performed by examining two-dimensional sections in histology. It is not always possible to comprehend structure-function integrity. Therefore, it was planned to obtain three-dimensional (3D) models of the capillaries in the placenta terminal villus by using the program developed in the Baskent University's laboratory and used in studies in different disciplines. The program's suitability for histology studies will also be assessed.Materials and Methods: A term placenta tissue sample was obtained from a 33-year-old healthy woman. Following the plastic embedding procedure, semi-thin serial sections were taken from these blocks. The sections were stained using toluidine blue and examined and photographed by using a light microscope. The 3D modeling procedure was conducted on the light micrographs of serial sections in order to reconstruct villous capillaries.Results: 3D images were obtained from two-dimensional light micrographs by using the same program. It was determined that the vessels running parallel to each other branched harmoniously, forming a capillary network in the terminal villus. Additionally, challenges encountered during the utilization of this program in histological studies are also presented in this study.Conclusion: Fetal blood reaches every part of the terminal villus through the branching capillary network. This feature would increase the surface area of vasculo-syncytial membrane and facilitate feto-maternal exchange. This can be clearly visualized by using 3D models. Three- dimensional modeling helps to understand the structure of all organs and tissues. Given that the current program is freely accessible, it will not incur additional costs for researchers and is open to further improvement by the programmer (erhankiziltan@gmail.com).