الفهرس 
Human HairOnly 14 pages are availabe for public view
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Abstract
Androgenetic alopecia (AGA) is a common genetic progressive non cicatricial hair disorder caused by susceptibility of hair follicles to androgens leading to their miniaturization. It is the most common type of alopecia affecting at least 50% of males and females worldwide. This type of alopecia occurs most commonly at the scalp frontal and vertex hair follicles sparing the occipital ones.
AGA is most probably a multifactorial familial disorder with a complex polygenic mode of inheritance caused by interactions among several genes and environmental factors. The pathogenesis of androgenetic alopecia involves both genetic and hormonal factors. The hair follicles are genetically targeted for androgen stimulation leading to hair follicles miniaturization and replacement of large, pigmented terminal hairs with shorter, thinner, depigmented vellus hairs in affected areas with shortening of the anagen phase of the hair cycle.
Hair follicles (HF) undergo continuous programmed cycling process called the hair growth cycle which is maintained throughout life by hair follicle stem cells (HFSCs). Those stem cells reside in a quiescent niche which is the bulge region. Progenitor cells (secondary germ cells) are direct progeny of HFSCs located just below the bulge in the lower follicle. They arise from the bulge during telogen and are immediately responsible for formation of the new hair follicle as the anagen begins. Each new hair cycle generates fresh progenitor cells from the bulge.
CD34 (cluster of differentiation 34) is a glycosylated cell surface transmembrane protein with prominent role in cell-cell adhesion. In the skin, CD34 is expressed in a variety of mesenchymal derived cells such as vascular endothelial cells, dermal dendritic/spindle-shaped cells, and perifollicular cells. CD34 is found to be expressed in the bulge region of mice hair follicles but not humans, where it marks HFSCs. In human, CD34 expression labels the exterior epithelial cells of the outer root sheath (ORS) situated just below the bulge of the anagen hair. SOX9 belongs to sex-determining region Y-type (SRY) highmobility group (HMG) box DNA-binding proteins family. It is a group of transcriptional regulators which have critical functions in a number of developmental processes, cell fate determination during development, as well as their role in establishing and maintaining stem and progenitor cell pools. SOX9 is an important marker for mouse bulge cells where it marks murine HFSCs and is required for their maintenance and survival. The goal of the present study was to explore the pathogenic role of SOX9 and CD34 in androgenetic alopecia patients through immunohistochemistry. This case-control study included 40 subjects with range of age between 18 and 44 years old; 14 males with androgenetic alopecia (AGA) and 6 females with female pattern hair loss (FPHL) and 20 age, sex and site matched healthy volunteers as a control group. Patients were chosen from Outpatient Clinic of Dermatology and Sexually transmitted diseases department, Menoufia University during the period from June 2021 to February 2022. Control participants with no prior history of androgenetic alopecia were selected from the Plastic Surgery Clinic. Each of the selected patients was subjected to complete detailed history taking and general examination. This was followed by dermatological examination and dermoscopic examination by Dermlite DL4 dermoscope to identify the criteria of AGA. Each subject was then subjected to biopsy taking. With a 3 mm punch, two scalp biopsies were obtained from each patient. The first one came from either bald frontal or vertex scalp (lesional biopsy) and the other from hairy occipital scalp (non-lesional biopsy). Additionally, each control subject had a frontal scalp punch biopsy obtained. All biopsies were delivered to Pathology Department, Faculty of Medicine, Menoufia University. Formalin fixed paraffin embedded blocks were prepared from each biopsy specimen from which several 5 micron (5um) thick sections were cut in longitudinal manner. Hematoxylin and eosin (H&E) staining was applied to one slide for standard histopathological analysis. Other slides were subjected to immunohistochemical staining to detect the immunohistochemical staining patterns of CD34 and SOX9.