## 4 Discussion
Collagen fibril diameters from both thick and thin sections of ovx rats receiving YCJ treatments in the current study were thicker than those of the control groups and the ovx group (Figure 8D,E), showing that both estrogen and YCJ are likely to influence collagen fibril diameters in ovx rats. Many studies have found that estrogen therapy improves collagen content and skin thickness [43; 44; 45; 46; 47]. Previous research involving a variety of phytoestrogens has backed up the current findings. For example, in human keratinocyte culture, [PERSON] et al. found that genistein and daidzein promote hyaluronic acid synthesis [48]. In a European trial of 234 postmenopausal women, isoflavone (Novadiol(r)) cream improved skin dryness and wrinkles after 12 weeks of treatment [49]. Raloxifene stimulates collagen production in human skin fibroblasts more efficiently than estradiol [50]. So far, phytoestrogens have been found to increase skin collagen thickness by:(1) inducing subcutaneous VEGF expression and increasing TGF-\(\beta\) in the skin [37; 51]; (2) reducing collagen degradation by increasing TIMP protein levels to inhibit MMPs [52; 53]; and (3) inhibiting FLT3 kinase activity and reducing Ras/mitogen-activated protein kinase/extracellular signal-regulated kinase and Akt/p70 ribosomal kinase pathways, to inhibit AP-1 activity and reduce gene transcription of MMP-1 [54]. Additional molecular pathways need to be elucidated. A single layer of columnar or high cuboidal keratinocytes rests on basement membrane in the epidermis' stratum basale. The basal domain of basal cells is anchored to the basement membrane by hemidesmosomes and associated intermediate filaments [42]. In the current study, the dermo-epidermal junctions of rats treated with YCJ (OJ groups) were not different from the NC and SC groups. The irregularities of the basal borders of the ovx(OC) and ovx+EB (OE)groups were markedly reduced compared with the control (NC, SC, and OJ) groups. This novel phenomenon indicates the obvious influences of YCJ on the protein component alteration of the hemidesmosomes of the stratum basale cell layer. Previously, it was found that phytoestrogens increase the production of hyaluronic acid [55] and extracellular matrix proteins [35], which gives rise to the hypothesis that it might help provide hemidesmosome structures in ovx rats treated with YCJ. However, the underlying molecular mechanisms need to be explored further in the future. Both EB and YCJ considerably enhanced the thickness of the skin, both the epidermis and dermis, and the collagen content, as measured by collagen fibril diameters, and raised the number of hair follicle densities in ovx rats, according to the findings. These protective effects were validated histologically by LM and TEM levels, indicating that YCJ can prevent skin aging even in the absence of estrogen. The skin is an estrogen-responsive tissue with specific receptors that respond to estrogen. While HRT has long been recommended to treat undesirable menopausal symptoms, as well as to prevent postmenopausal osteoporosis and other risk factors like heart attack and stroke, many studies have linked HRT to an increased risk of cardiovascular complications, venous thromboembolism, coronary artery disease [56], and many types of cancer [57; 58; 59]. As a result, the risks and benefits of systemic HRT have been thoroughly examined. Thus, HRT is not suggested for the treatment of skin aging, and topical estrogen cannot be used until clinical research has been completed to determine the minimum levelsof estrogen compounds that have the best local effects without creating systemic hormonal side effects. The question as to whether estrogen substitutes like phytoestrogens and SERMs are effective estrogens for mitigating skin aging in postmenopausal women has to be explored further.