Histological and immunohistochemical investigations of ovarian interstitial glands during non-breeding season in camels (Camelus dromedarius)

Effects of follicular and luteal cysts on reproductive organs, interstitial glands, and mast cell distribution in buffalo ovaries

A significant factor contributing to reproductive failure in dairy cattle that raised the possibility of culling was ovarian cysts. Its etiology and pathogenesis remained a puzzle, but investigation of the associated tissue modulation, particularly those of the ovaries, oviduct, and uterus, might shed some light on its development. Therefore, the current study aimed to assess changes induced by follicular and luteal cyst formation in the ovary, oviduct, and uterus. In addition, the aims also involved the effect of these cyst formations on the interstitial glands and mast cell distribution in the ovaries of dairy cows. Genital organs of healthy, non-pregnant buffalo-cows (n = 45) were collected from the abattoir. According to the ovarian status, buffalo-cows were divided into three equal groups (15 for each): one normal healthy group was the control group (Ctrl group) and two diseased groups. The first diseased group was the group of buffalo-cows with follicular cysts (FC group), while the second one was the group with luteal cysts (LC group). Blood and tissue samples were collected to determine progesterone levels and do histological investigations of the reproductive organs. Hematoxylin and eosin, Alcian blue-PAS, and Alcian blue-safranin-O stains were used for investigating ovarian tissues, interstitial glands (IGs), and mast cells (MCs), respectively. Results showed that significantly reduced thickness of the ovarian cortex and medulla, loss of ovarian folliculi, hemorrhage, and dilated blood vessels were observed in the FC and LC groups compared to the Ctrl group. In addition, the cystic ovaries significantly reduced interstitial gland count that was characterized by histopathological alterations that included atrophied and apoptotic cells and fragmentation, fading, and pyknotic nuclei. Likewise, in cystic ovaries, mast cell counts were found significantly reduced compared to the Ctrl group. The ovarian cysts significantly reduced the length and diameter of oviductal mucosal villi that were characterized by severe histopathological fluctuation in the ciliated cells and protruding and non-protruding secretory cells. For the uterus, the average thickness of the myometrium and endometrium in the ovarian cyst groups was significantly reduced compared to the Ctrl group. Furthermore, histopathological changes in the uterine glands, including severe apoptotic alterations, fading, pyknotic, and fragmented nuclei, were observed. In conclusion, the current study indicated that follicular and luteal cyst formations in the ovary induced various changes in the reproductive organs, interstitial glands, and mast cell distribution in the ovarian stroma, providing insights into the potential pathogenesis of cyst formation.

Spatial Transcriptomics of Aging Rat Ovaries Reveals Unexplored Cell Subpopulations with Reduced Antioxidative Defense

INTRODUCTION

Ovarian aging is characterized by a gradual decline in quantity and quality of oocytes and lower chance of fertility. Better understanding the genetic modulation during ovarian aging can further address available treatment options for aging-related ovarian diseases and fertility preservation.

METHODS

A novel technique spatial transcriptomics (ST) was used to investigate the spatial transcriptome features of rat ovaries. Transcriptomes from ST spots in the young and aged ovaries were clustered using differentially expressed genes. These data were analyzed to determine the spatial organization of age-induced heterogeneity and potential mechanisms underlying ovarian aging.

RESULTS

In this study, ST technology was applied to profile the comprehensive spatial imaging in young and aged rat ovary. Fifteen ovarian cell clusters with distinct gene-expression signatures were identified. The gene expression dynamics of granulosa cell clusters revealed three sub-types with sequential developmental stages. Aged ovary showed a significant decrease in the number of granulosa cells from the antral follicle. Besides, a remarkable rearrangement of interstitial gland cells was detected in aging ovary. Further analysis of aging-associated transcriptional changes revealed that the disturbance of oxidative pathway was a crucial factor in ovarian aging.

CONCLUSIONS

This study firstly described an aging-related spatial transcriptome changes in ovary and identified the potential targets for prevention of ovarian aging. These data may provide the basis for further investigations of the diagnosis and treatment of aging-related ovarian disorders.

The relationship between ovarian hormones and mast cell distribution in the ovaries of dromedary camel (Camelus dromedaries) during the follicular wave

Background and Aim: Mast cells (MCs) play an essential role in regulating tissue homeostasis through various non-allergic immune reactions. This study aimed to describe the salient features of MCs during different phases of the estrous cycle and evaluate the relationship between ovarian hormones and the presence of MCs in camel ovaries. Materials and Methods: Genital tracts (n = 28) of healthy, non-pregnant camels were collected from a local slaughterhouse. The follicular wave stage was determined according to structures on the ovaries using an ultrasound device. Stages were classified as "growing" (n = 12, FØ = 0.3–0.8 cm), "mature" (n = 9, FØ = 0.9–2.2 cm), or "regression" phase (n = 7, FØ >2.5). Blood samples were collected at slaughter to determine serum estradiol-17β and progesterone levels using an immunoassay. Safranin-O, periodic acid/Schiff, alcian blue, or methylene blue stains were used to detect MCs. Results: Follicular numbers at the growing, mature, and regression phases were determined to be 36, 14, and 7 follicles, respectively. Mast cells were widely but sparsely distributed within the ovarian tissue (9.3 MCs in the growing phase, 10.7 in the mature phase, and 7.0 in the regression phase). Typical histological features of MCs were observed in ovarian stromal tissue. Some MCs were found in the interstitial tissue, either near the follicular wall or the interstitial gland. Mast cells were present at a higher density during the mature phase than in the growing and regression phases in the ovarian matrix. A significantly reduced presence of MCs was found in the regression phase than in both the growing and mature phases (p < 0.05). A very strong positive correlation was observed between serum estradiol-17β concentrations and MC density in the ovaries (r = 0.9; p < 0.001). In addition, a strong negative correlation (r = –0.65; p = 0.03) was observed between the presence of MCs and serum progesterone concentrations. Conclusion: These findings suggest that the follicular wave phase and the associated hormonal concentration induce changes in the number of MCs in the camel ovary.

Paraffin-embedding for large volume bio-tissue

Acquiring ultrahigh-resolution three-dimensional images of large-volume tissues non-human primate tissues was an enormous challenge. Given the preservation of structure and excellent sectioning property, formalin-fixed paraffin-embedding method had an enormous potential for three-dimensional reconstruction of fine structures, based on the very thin histological sections and optical images. However, maintaining the structure uniformly in large-volume tissues was difficult during the complex processes. In this study, we presented a detailed protocol for the whole mouse, rat, rabbit brains, and even for the macaque hemisphere. The entire protocol took about 2–30 days to complete for a large sample, including fixation, dehydration, clearing, wax immersion and embedding. In addition, it could be applied to other species and organs, while the embedding processes depended on the size and the type of organs. This method had wide applicability to serve as a baseline for further technique development.