The histological and biochemical analysis of the effects of radiofrequency radiation on testis tissue of rats and the protective effect of melatonin.

Background/aim: Primarily due to wireless communication devices, especially mobile phones, there has been a steady rise in the intensity of nonionizing radiofrequency radiation (RFR). In recent years, increased human health problems raised concerns about whether there is a positive relationship between intense exposure to RFR and public health. The present study aims to investigate the effects of GSM-like RFR exposure on the male reproductive system and the impact of melatonin treatment (synergistic, antagonist, or additive). Materials and methods: Thirty-six male Wistar Albino rats were used and separated into six groups: i. Control; ii. Sham; iii. RFR exposure; iv. Control-melatonin; v. Sham-melatonin; vi. Melatonin + RFR exposure. Animals were exposed to 2600 MHz RFR with electric (E) field levels of 21.74 V/m for 30 min per day, 5 days per week, for 4 weeks. All testicular tissue samples were evaluated under a light microscope for hematoxylin-eosin staining. Biochemical analyses were performed by measuring malondialdehyde, total nitric oxide, glutathione, and glutathione peroxidase levels. We evaluated the combined effects of prolonged RFR exposure and melatonin treatment on ROS-mediated structural changes in testicular tissues. Results: Results showed that reactive intermediates (malondialdehyde and total nitric oxide) increased significantly with RFR exposure, while the protective effect of melatonin effectively reduced the radical levels of the tissues. Histological evaluation revealed a decrease in cell population and connective tissue elements under RFR exposure, accompanied by marked edema in the testicular tissues. Conclusion: The structural and functional effects of prolonged RFR exposure might be ROS-based. Moreover, these adverse effects might be compensated with externally treated supplements. There is a need for new extensive research.

Biological nerve conduit model with de-epithelialized human amniotic membrane and adipose-derived mesenchymal stem cell sheet for repair of peripheral nerve defects.

In this study, a biological conduit, consisting of an adipocyte-derived mesenchymal stem cell (AdMSCs) sheet and amniotic membrane (AM), was designed for the reconstruction of peripheral nerve defects. To evaluate the effect of the produced conduit on neural regeneration, a 10-mm sciatic nerve defect was created in rats, and experiments were carried out on six groups, i.e., sham control group (SC), negative control group (NC), nerve autograft group (NG), the biological conduit (AdMSCs + AM) group, the commercial PGA tube conduit (PGA) group, and the conduit only consisting of AM (AM) group. The effects of different nerve repair methods on the peripheral nerve and gastrocnemius muscle were evaluated by functional, histological, and immunohistochemical tests. When the number of myelinated axons was compared between the groups of AdMSCs + AM and PGA, it was higher in the AdMSCs + AM group (p < 0.05). The percentage of gastrocnemius collagen bundle area of AdMSCs + AM group was found to be statistically lower than the PGA group (p < 0.05). The muscle fiber diameter of AdMSCs + AM group was lower than that of the NG group, but significantly higher than that of the PGA group and the AM group (p < 0.001). Muscle weight index was significantly higher in the AdMSCs + AM group compared to the PGA group (p < 0.05). It was observed that nerve regeneration was faster in the AdMSCs + AM group, and there was an earlier improvement in pin-prick score and sciatic functional index compared to the PGA group and the AM group. In conclusion, the biological conduit prepared from the AdMSCs sheet and AM is regarded as a new biological conduit that can be used as an alternative treatment method to nerve autograft in clinical applications.

Electron microscopic investigation of benzo(a)pyrene-induced alterations in the rat kidney tissue and the protective effects of curcumin.

Benzo(a)pyrene (BaP) is a polycyclic hydrocarbon with carcinogenic and DNA damaging properties. Curcumin, primary yellow pigment in turmeric, has a wide range of biological, pharmacological properties in addition to being a powerful antioxidant. The aim of this study was to investigate protective effects of curcumin against benzo(a)pyrene damage in rat kidney. Thirty-six male Wistar albino rats were divided into six groups (n = 6) as: control, corn oil, Dimethyl sulfoxide (DMSO), BaP (10 mg/kg/day), Curcumin (100 mg/kg/day), Curcumin+BaP (100 mg/kg/day+10 mg/kg/day). Agents were daily and orally administered for six weeks. Kidney tissues were removed and examined ultrastructurally. Glomerular and tubular structures in control, corn oil, and DMSO groups demonstrated normal features. Glomerular capillary dilation, thickening, and folding of basement membrane and disruption of organelle contents were distinguished in BaP group. Deletion of podocyte cell and pedicels also sponge-like appearance of glomerular surface were remarkable in this group. Tissue components were protected in curcumin treated group. Proximal tubules and glomerular basement membrane exhibited normal features in Curcumin+BaP group. The abnormalities that accompanied BaP administration clearly revealed the detrimental effects of this agent. Therefore, this study provided substantial evidence that curcumin protects against benzo(a)pyrene nephrotoxicity.

Effects of 2600 MHz Radiofrequency Radiation in Brain Tissue of Male Wistar Rats and Neuroprotective Effects of Melatonin.

The debate on the biological effects of radiofrequency radiation (RFR) still continues due to differences in the design of studies (frequency, power density, specific absorption rate [SAR], exposure duration, cell, tissue, or animal type). The current study aimed to investigate the effects of 2,600 MHz RFR and melatonin on brain tissue biochemistry and histology of male rats. Thirty-six rats were divided into six groups randomly: cage-control, sham, RFR, melatonin, sham melatonin, and RFR melatonin. In RFR groups, animals were exposed to 2,600 MHz RFR for 30 days (30 min/day, 5 days/week) and the melatonin group animals were subcutaneously injected with melatonin (7 days/week, 10 mg/kg/day) for 30 days. SAR in brain gray matter was calculated as 0.44 and 0.295 W/kg for 1 and 10 g averaging, respectively. RFR exposure decreased the GSH, GSH-Px, and SOD levels and increased the MPO, MDA, and NOx levels (P < 0.005) significantly. RFR exposure also led to an increase in structural deformation and apoptosis in the brain tissue. This study revealed that exogenous high-dose melatonin could reduce these adverse effects of RFR. Limiting RFR exposure as much as possible is recommended, and taking daily melatonin supplements may be beneficial. Bioelectromagnetics. © 2021 Bioelectromagnetics Society.

Does Exposure of Smart Phones during Pregnancy Affect the Offspring's Ovarian Reserve? A Rat Model Study.

OBJECTIVE: We investigated the effect of prenatal exposure to smart phone radiation and the protective effect of omega-3 on ovarian reserve of offspring. Methods: 24 pregnant Wistar albino rats were divided into four groups. Group-I received neither radiofrequency (RF) radiation nor omega-3, group-II received RF, group-III received RF radiation and 300 mg omega-3 and group-IV received RF radiation and 600 mg Omega-3 till birth. At 42 days, bilateral oophorectomy was performed on all female offspring for follicle count and immunohistochemical staining (GDF9, FOXO1 and TUNEL). Results: Group-II had significantly lower mean number of primordial (p = 0.006), secondary follicles(p = 0.003) and a higher atresia score. Group-III variables were comparable with group-I variables. Group-IV had statistically higher median number of atretic follicles than group-I (p = 0.023). Conclusions: Ovarian reserve of offspring diminished with RF exposure during pregnancy. Omega-3 supplementation during pregnancy may reduce the potential premature ovarian failure.

Neuroprotective role of delta opioid receptors in hypoxic preconditioning

Background/aim: The purpose of the present study was to explore the neuroprotective role of delta opioid receptors (DOR) in the rat cortex in hypoxic preconditioning. Materials and methods: Rats were randomly divided into 8 groups: control (C), sham (S), hypoxic preconditioning (PC), severe hypoxia (SH), PC + SH, PC + SH + Saline (PS), PC + SH + DPDPE (DPDPE, selective DOR agonist), PC + SH + NT (NT, Naltrindole, selective DOR antagonist). Drugs were administered intracerebroventrically. Twenty four h after the end of 3 consecutive days of PC (10% O2, 2 h/day), the rats were subjected to severe hypoxia (7% O2 for 3 h). Bcl-2 and cyt-c were measured by western blot, and caspase-3 was observed immunohistochemically. Results: Bcl-2 expressions in the PC group were higher than in control, SH, and PC + SH groups. Even though there were no significant differences between the groups in terms of cyt-c levels, caspase-3 immunoreactivity of cortical neurons and glial cells in the severe hypoxia and NT groups were higher than in the control, sham, and hypoxic preconditioning groups. DPDPE administration diminished caspase-3 immunoreactivity compared with all of the severe hypoxia groups. Conclusions: These results suggest that cortical cells are resistant to apoptosis via increased expression of Bcl-2 and decreased immunoreactivity of caspase-3 in the cortex, and that DOR is involved in neuroprotection induced by hypoxic preconditioning via the caspase-3 pathway in cortical neurons.

Is leptin receptor expression triggered in the case of embryo transfer to endometrium coculture?

Background/aim: A synchronized dialogue between maternal and embryonic tissues is required for successful implantation. Low uterine receptivity is responsible for two-thirds of implantation failures and leptin is effective in the physiology of reproduction by binding to specific receptors. In this study, we investigateleptin receptor expression in cases of embryo transfer to endometrial coculture. Materials and methods: Biopsy materials were taken from 20 females with indication for coculture application and were cultured in an appropriate medium after the epithelial cells were isolated. The grown cells were cultured in chamber slides as the first group. For the second group, day 3 embryo was added to chamber slides and the development was observed. The embryo was transferred 1 or 2 days later and other cells (after the transfer process) were used to form the second group. After fixation, immunohistochemical staining was performed with anti-leptin primary antibody. Results: Regarding the coculture without embryo transfer, moderate leptin receptor immunoreactivity was seen in the perinuclear region and the cell membrane. Also, regarding the coculture with embryo transfer, moderate leptin receptor immunoreactivity was seen in the cytoplasm and strong leptin receptor immunoreactivity was seen in the cell membrane. Conclusion: Embryo transfer to endometrium coculture triggers leptin receptor expression

Sutureless approach with vein grafts and mesenchymal stem cells in primary nerve repair: Functional and immunohistological results.

PURPOSE: The aim of this study was to define a sutureless peripheral nerve repair technique with a vein graft and bone marrow-derived stem cells (BMSC) and compare it to epineural repair. MATERIALS AND METHODS: Thirty Wistar Albino rats were divided into five groups evenly. In the control group (C), epineural repair was performed. In the SV (suture + vein) and MSV (BMSC + suture + vein) groups, epineural repair was wrapped with a vein graft. In the V (vein) and MV (vein + BMSC) groups, sutureless repair using a vein graft was performed by taking sutures away from the regeneration site. Rats were evaluated with pinprick, toe spread tests and sciatic nerve index (SFI) at 4th, 8th, and 12th weeks. They were sacrificed at 12th week, repair sites were harvested and evaluated immunohistochemically. RESULTS: There was no difference in pinprick and toe spread tests between the groups at 12th week. The mean SFI was -76.5 ± 3.7, -65.2 ± 11.7, -46.2 ± 19.4, -68.8 ± 9.8, -56 ± 8.8 in the C, SV, MSV, V, MV groups, respectively. The MSV group showed significantly the best SFI results (P < .05). NF-H immunostaining scores were as C; 1 ± 0.18, SV; 2.5 ± 0.36, MSV; 4 ± 0.49, V; 1.56 ± 0.54, MV; 3 ± 0.39, whereas GAP-43 scores were as C; 1 ± 0.31, SV; 2.66 ± 0.56, MSV; 4.50 ± 0.23, V; 2 ± 0.23, MV; 3 ± 0.6. The best nerve regeneration according to immunostaining results was observed in the MSV group (P < .05). The mean fibrosis area was 221.5 ± 25.9, 101.6 ± 7.1, 121.3 ± 18.8, 150.3 ± 12.1, 152.4 ± 11.8 µm2 in the above groups, respectively. SV and MSV groups showed the significantly less fibrosis area (P < .05). CONCLUSION: Epineural suture repair combined with vein wrapping and BMSCs (MSV) showed the best SFI, GAP-43, and NF-H immunostaining results.

The fluoroquinolones may positively affect tendon healing after surgical repair.

OBJECTIVES: This study aimed to evaluate the biomechanical and histological effects of fluoroquinolones on surgically repaired tendon healing. MATERIALS AND METHODS: The Achilles tendons of 40 Wistar rats (mean weight: 213.5 g; range 201 to 242 g) were bilaterally surgically cut and repaired. The rats were randomly divided into four groups: the first and third groups were designated as control groups and did not receive drug therapy, whereas the second and fourth groups received 300 mg/kg ciprofloxacin for a week after the surgical procedure. The first and second groups had both tendons dissected at the end of the first week, while the third and fourth groups were dissected at the end of the third week. The left tendons were examined biomechanically, while the right tendons were examined histologically. RESULTS: Statistical analysis revealed that the mean maximum tensile forces of tendons in the first and second groups were 5.2±1.84 N (range, 2.9 to 8.5 N) and 11.1±2.65 N (range, 7.3 to 13.9 N), respectively, which was found to be statistically significant (p< 0.05). At the end of the third week, mean maximum tensile forces of the third and fourth groups were determined to be 20.7±5.0 N (range, 22.1 to 29.8 N) and 28.7±4.6 N (range, 22.1 to 36.8 N), respectively, which was also statistically significant (p< 0.05). Histologically, our results were compatible. CONCLUSION: This study demonstrated that ciprofloxacin did not exhibit the expected adverse effects on surgically repaired tendon healing in the early stages but likely contributed to healing in the short term by affecting the inflammatory phase.

Acyl ghrelin, desacyl ghrelin and their ratio affect hepatic steatosis via PPARγ signaling pathway.

BACKGROUND AND STUDY AIMS: Ghrelin is an appetite hormone-containing 28-amino acid and has 4 different forms in the body. Ghrelin forms have different physiological functions in the body. This study aims to analyze the effect of acyl and desacyl ghrelin hormone on hepatic steatosis and biochemical findings in 36 male Wistar rats. MATERIALS AND METHODS: Rats were split into 6 equal groups, consisting of control, acyl ghrelin, desacyl ghrelin, acyl/desacyl 3:1, acyl/desacyl 1:1, and acyl/desacyl 1:3 groups, and administered placebo or 200 ng/kg hormone subcutaneous twice a day for 14 days. Oral Glucose Tolerance Test (OGTT) was performed on Day 15, Insulin Tolerance Test (ITT) on Day 16, and scarification procedure on Day 17. Certain biochemical data and liver diacylglycerol (DAG), glycogen, protein kinase C and PPAR-γ levels were detected in the blood. Histological analyses were also conducted on the liver tissues. RESULTS: The highest plasma total cholesterol and VLDL-K levels were found in the acyl/desacyl 1:3 group, and lower insulin, and HOMA-IR levels were found in groups where acyl and desacyl were administered together (p < 0.05). PPAR-γ gene expression level increased in acyl ghrelin and acyl/desacyl 1:3 groups compared to the control group. Protein kinase C gene expression was highest in the acyl/desacyl 1:3 group. The most severe degenerative findings compliant with steatosis in the liver were observed in the acyl ghrelin group (p < 0.05). CONCLUSION: It was determined that administering rats acyl alone and acyl/desacyl by 1:3 caused the highest PPAR-γ gene expression, serum total cholesterol, HDL-K, and VLDL-K levels in the body. Besides, it is shown that desacyl ghrelin effectively regulates the blood glucose level when administered alone.

Effects of Blue Light on Puberty and Ovary in Female Rats

Objective: This study was designed to examine the effect of blue light exposure and exposure time on puberty in an animal model. Methods: Eighteen 21-day-old female Sprague Dawley rats were divided into three equal groups which were: control group (CG); blue light-6 hours (BL-6); and blue light-12 hours (BL-12). CG rats were maintained with 12/12-hour light-dark cycles. The animals in BL-6 and BL-12 were exposed to blue light of wavelength 450-470 nm and intensity of 0.03 uW/cm2 for 6 and 12 hours, respectively. Exposure to blue light continued until the first signs of puberty. Serum follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, testosterone, dehydroepiandrosterone sulfate (DHEA-S), leptin and melatonin were measured. Subsequently the ovaries and uterus were examined histomorphologically. Results: The median day of puberty start was 38, 32 and 30 for the CG, BL-6, and BL-12 groups, respectively (p=0.001). FSH, testosterone, DHEA-S, and leptin concentrations of all groups were similar. However, LH and estradiol concentrations in BL-6 were higher compared to CG (p=0.02). There was a negative correlation between blue light exposure, exposure time, and melatonin concentrations (r=-0.537, p=0.048). Ovarian tissue was compatible with puberty in all groups. As blue light exposure time increased, capillary dilatation and edema in the ovarian tissue increased. Prolonged exposure was associated with polycystic ovary-like (PCO) morphological changes and apoptosis in granulosa cells. Conclusion: These results suggest that exposure to blue light and the duration of exposure induced earlier puberty in female rats. As the duration of blue light exposure increased, PCO-like inflammation, and apoptosis were detected in the ovaries.

Evaluation of The Effects of Carob (Ceratonia siliqua L.) Fruits on the Puberty of Rats

Objective: This study was planned to determine the effects of carob use on puberty because of the observation of early puberty or pubertal variants due to the long-term use of carob in our clinic. Methods: Forty-eight Wistar albino rats, on postnatal day 21, were assigned into two groups female (n=24) and male (n=24). Groups were divided into four groups Control, and Carob-150, Carob-300, and Carob-600. Ceratonia siliqua L. extract was given to rats in a 0.5% carboxymethylcellulose (CMC) solution. CMC (0.5%) was given to the control, Ceratonia siliqua L. extract was given 150 mg/kg/day to the Carob-150, 300 mg/kg/day to the Carob-300, 600 mg/kg/day to the Carob-600 by oral gavage. The treatments were performed once daily until the first sign of puberty. Serum follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, total testosterone, leptin, glutathione, glutathione peroxidase (GPx), and malondialdehyde were measured by commercial rat-specific ELISA kits. Testis, uterus and ovarian tissue were examined histologically. Results: The median time of preputial separation in male rats was 38th, 31st, 31st, and 31st days in the Control, Carob-150, Carob-300, and Carob-600 groups, respectively (p=0.004). The median day of vaginal opening day was the 39th, 31st, 34th, and 31st days in the Control, Carob-150, Carob-300, and Carob-600 groups, respectively (p=0.059). FSH, LH, testosterone (male), estradiol (female) and leptin levels of the groups were similar. However, GPx levels were higher in male and female animals given C. siliqua extract compared to the Control (male p=0.001 and female p=0.008). Testicular and ovarian tissues were concordant with the pubertal period in all groups. As the dose of Ceratonia siliqua extract increased, it induced spermatogenesis and spermiogenesis, causing abnormal changes, such as ondulation in the basement membrane, capillary dilatation, and increased congestion in males. In females, edema in the medulla gradually increased with increased dosage, and granulosa cell connections were separated in Carob-300 and Carob-600 groups. Conclusion: This study demonstrated that C. siliqua caused early puberty and increased spermiogenesis and folliculogenesis. Antioxidant mechanisms were impaired with increasing dose, possibly leading to tissue damage at high doses.

Impact of 5'-AMP-activated protein kinase (AMPK) on Epithelial Sodium Channels (ENaCs) in human sperm.

Hyperpolarization is associated with decreased intracellular Na+ concentration through the closure of the epithelial Na+ channels (ENaCs) during capacitation. 5'-AMP-activated protein kinase (AMPK) is involved in the regulation of Na+ transport by reducing ENaC-ß abundance in the plasma membrane in somatic cells. However, it is not known whether AMPK acts on ENaCs in sperm. The aim of the present study was to analyze the role of AMPK activation in the regulation of ENaC and to examine its relationship with capacitation-associated hyperpolarization of human sperm. Human sperm were treated with AICAR (AMPK activator) in non-capacitating and capacitating conditions. AMPK activity and ENaC-ß concentration were evaluated by ELISA. Flow cytometry was used to measure tyrosine phosphorylation, hyperpolarization, intracellular Na+ concentration and acrosome reaction. Immunofluorescence staining was carried out to analyze the distribution of ENaC-ß and CD46 in sperm. We found that induction of capacitation triggered AMPK phosphorylation. AMPK activation by AICAR increased tyrosine phosphorylation. AICAR decreased ENaC-ß levels, mainly localized at the principal-piece of the flagellum, resulting in lower intracellular Na+ concentration and increased hyperpolarization of the plasma membrane. Altogether, these data provide evidence that AMPK activation is involved in capacitation-associated hyperpolarization by reducing ENaC abundance in human sperm.

Involvement of endometrial IGF-1R/IGF-1/Bcl-2 pathways in experimental polycystic ovary syndrome: Identification of the regulatory effect of melatonin.

The involvement of endometrial IGF-1R/IGF-1/Bcl-2 pathways and the potential regulatory effects of exogenously administrated melatonin on this expression is investigated in the experimental PCOS model in the present study. Thirty-two 6-8 week old Sprague Dawley rats were divided into four groups: the Sham Control Group (1% CMC/day by oral gavage [o.g.]); the Melatonin Group (2 mg/kg/day melatonin by subcutaneous administration [s.c.]); the Experimental PCOS Group (1 mg/kg/day Letrozole by o.g.); and the Experimental PCOS + Melatonin Group (1 mg/kg/day Letrozole by o.g. and 2 mg/kg/day melatonin by s.c. administration). Vaginal smear samples were taken from the 14th day to the end of the experiment for colpocytological measurements. At the end of the 21 day experimental period, uterine tissues were taken; Hematoxylin-Eosin histochemical, IGF-1R/IGF-1/Bcl-2, PCNA immuno-histochemical stainings and western blot analyses were performed for related antibodies. All of the data was supported statistically. The epithelium of endometrium lost its single-layer structure in some parts, separation was observed between the epithelium and the basal membrane junction, intracellular edema was found in the uterine glands by the polycystic ovary-induction. Also this induction increased the expression of IGF-1R/IGF-1, Bcl-2, and PCNA proteins. Morphological degenerations returned to its normal appearance generally by the melatonin administrations and melatonin also regulated the increased expression of endometrial IGF-1R/IGF-1/Bcl-2 and PCNA pathways. It is concluded that additional studies are needed, using melatonin as a supporting agent may be appropriate in cases of PCOS.

Bacopa Monnieri Protects the Directly Affected Organ as Well as Distant Organs Against I/R Injury by Modulating Anti-Inflammatory and Anti-Nitrosative Pathways in A Rat Model for Infra-Renal Aortic Occlusion.

OBJECTIVE: To investigate the protective effect and underlying mechanisms of B. monnieri, a medicinal plant, on kidney and skeletal muscle injury induced by infra-renal abdominal aorta clamping for 2-hours (ischemia) and following removal of the clamp (reperfusion, 2-hours). METHODS: Rats were divided into four groups (n = 6): (I) animals given only saline (sham-control); (II) animals given B. monnieri extract for 10-days (300 mg/kg/day) (Bacopa-treated sham); (III) animals subjected to ischemia/reperfusion (I/R); (IV) animals given B. monnieri extract and then subjected to I/R. Kidneys and lower extremity muscles were examined for GPx, CAT, iNOS, 3-NT, IL-1ß and TNF-α. Apoptosis and injury were evaluated by TUNEL and H&E staining, respectively. RESULTS: I/R resulted in TUNEL positive cells, periarterial edema and glomerular capillary dilatation, decreased GPx activity, unchanged CAT, iNOS, 3-NT, IL-1ß and TNF-α in kidney. B. monnieri minimized renal remote reperfusion injury, and Group IV showed a lower degree of renal histopathology score when compared to the others. B. monnieri mitigated muscle I/R injury, decreased muscle hypertrophy, myofibril abnormalities and apoptosis. Muscle 3-NT and cytokine levels were increased by I/R, and B. monnieri inhibited iNOS and 3-NT both in sham-control and I/R groups. Muscle GPx unaffected by I/R or B. monnieri, but CAT was inhibited only in B. monnieri-treated I/R group. Muscle iNOS, 3-NT, IL-1ß, TNF-α levels and CAT activity of B. monnieri-treated I/R rats were lower than those in sham-control or Bacopa-treated sham. CONCLUSIONS: B. monnieri can protect the directly affected organ as well as distant organs against I/R injury by modulating anti-inflammatory and anti-nitrosative pathways.

The effect of equine-derived bone protein extract (Colloss-E) in the treatment of cavitary bone defects: an experimental study.

OBJECTIVE: Bone protein extract (BPE) usually requires a carrier or a scaffold for implantation. We aimed to compare the effect of equine-derived BPE, an osteoinductive agent composed of a high amount of type-I collagen and other bone proteins (Colloss-E), with that of human demineralized bone matrix (DBM) for treating cavitary bone defects not requiring scaffold use. METHODS: Rabbit distal femoral condyle was used as a stable cavitary bone defect model. Bone defects of 6-mm diameter and 10-12-mm depth were created in the femoral condyles. Rabbits were assigned into the equine-derived BPE (BPE), human-derived DBM (DBM), and control (C) groups. Approximately 20 mg of BPE was implanted into the defect in the equine-derived BPE group (n=6), whereas 0.3 cc of DBM was implanted in the DBM group (n=6). Defects were left empty in the C group (n=6). The defect area was histologically examined after 6 weeks. RESULTS: There were no instances of macroscopic defect collapse or failure. Histopathological examination revealed that the BPE group had better scores (statistically significant) than both the other groups in terms of quality of union. The BPE group also had higher scores than the DBM group in terms of graft incorporation and new-bone formation. CONCLUSION: The current study revealed results consistent with those of the previous studies concerning BPEs. Equine-derived BPE was found to be successful for treating cavitary bone defects not requiring scaffold use.