Pregnancy outcomes of monochorionic diamniotic and dichorionic diamniotic twin pregnancies conceived by assisted reproductive technology and conceived naturally: a study based on chorionic comparison.

OBJECTIVE: To evaluate monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA) twin pregnancies conceived by assisted reproductive technology (ART) and conceived naturally. METHODS: We retrospectively analyzed the data on twin pregnancies conceived by ART from January 2015 to January 2022,and compared pregnancy outcomes of MCDA and DCDA twins conceived by ART with those of MCDA and DCDA twins conceived naturally, pregnancy outcomes between MCDA and DCDA twins conceived by ART, and pregnancy outcomes of DCT and TCT pregnancies reduced to DCDA pregnancies with those of DCDA pregnancies conceived naturally. RESULT: MCDA pregnancies conceived by ART accounted for 4.21% of the total pregnancies conceived by ART and 43.81% of the total MCDA pregnancies. DCDA pregnancies conceived by ART accounted for 95.79% of the total pregnancies conceived by ART and 93.26% of the total DCDA pregnancies. Women with MCDA pregnancies conceived by ART had a higher premature delivery rate, lower neonatal weights, a higher placenta previa rate, and a lower twin survival rate than those with MCDA pregnancies conceived naturally (all p < 0.05). Women with DCDA pregnancies conceived naturally had lower rates of preterm birth, higher neonatal weights, and higher twin survival rates than women with DCDA pregnancies conceived by ART and those with DCT and TCT pregnancies reduced to DCDA pregnancies (all p < 0.05). CONCLUSION: Our study confirms that the pregnancy outcomes of MCDA pregnancies conceived by ART are worse than those of MCDA pregnancies conceived naturally. Similarly, the pregnancy outcomes of naturally-conceived DCDA pregnancies are better than those of DCDA pregnancies conceived by ART and DCT and TCT pregnancies reduced to DCDA pregnancies.

Evaluation of Regenerative Efficacy of Amnion and Chorion Membrane in Treatment of Mandibular Molar Furcation Defects: A Clinico-radiographic Study.

AIM: Amnion and chorion membranes possess unique inherited biological properties that enhance wound healing and may accelerate periodontal regeneration. The present study aims to evaluate and compare the efficacy of amnion and chorion membranes in the treatment of furcation defects. MATERIALS AND METHODS: A total of 20 patients were selected and were randomly allocated to group I and group II with 10 subjects in each group. Amnion and chorion membranes are placental-derived membranes that accelerate regeneration by having natural growth factors with their antimicrobial and inflammation reduction properties. Group I was treated using bone grafting with decalcified freeze-dried bone allograft (DFDBA) and placement of amnion as a membrane for guided tissue regeneration (GTR) whereas group II was treated using bone grafting with DFDBA and placement of chorion as a membrane for GTR. The patients were followed for clinical and radiographic parameters and were evaluated between 3 and 6 months after surgery. RESULT: In intragroup comparison, a significant difference was evident in both the groups for all the clinical and radiographic parameters within the groups. (p = 0.01) This means both amnion and chorion membranes showed statistically significant regenerative efficacy. In intergroup comparison, the results show that all the clinical parameters and radiographic parameters show no significant difference between the groups. CONCLUSION: The amnion and chorion membranes had similar regenerative efficacy in combination with DFDBA in patients with buccal degree II furcation defects in mandibular molars. CLINICAL SIGNIFICANCE: The amnion and chorion membranes have shown significant improvement in clinical and radiographic parameters when used for the treatment of buccal degree II furcation defects in mandibular molars. How to cite this article: Mallapragda S, Gupta R, Gupta S, et al. Evaluation of Regenerative Efficacy of Amnion and Chorion Membrane in Treatment of Mandibular Molar Furcation Defects: A Clinico-radiographic Study. J Contemp Dent Pract 2024;25(2):160-167.

Evaluation of Leukocyte Chemotaxis Induced by Human Fetal Membranes in an In Vitro Model.

Leukocyte infiltration into the maternal-fetal interface is a consequence of the robust inflammation in the gestational tissues during term labor and preterm labor with or without infection. During pregnancy, the fetal membranes act as a physical barrier that isolates the fetus into the amniotic cavity, keeping it in an optimal environment for its development. In addition, the fetal membranes possess immunological competencies such as the secretion of cytokines and chemokines in response to different stimuli. Clinical and experimental evidence indicates that these tissues are involved in the extensive chemotaxis of immune cells in normal or pathological conditions.Few studies have evaluated the chemotactic capacities of the fetal membranes considering that this tissue is composed of two adjacent tissues, the amnion and the chorion, which have different characteristics. Although these tissues function as a unit, their response is complex since there is an interaction between them, where each tissue contributes differently. The protocol described here allows us to evaluate the in vitro chemotactic capacities of fetal membranes in response to various applied stimuli, considering the contribution of each of their components (amnion and choriodecidua) using a Boyden chamber assay and phenotyping the chemo-attracted leukocytes by flow cytometry.

Culture of Human Fetal Membranes in a Two Independent Compartment Model: An Ex Vivo Approach.

During pregnancy, the fetal membranes composed of the amnion and chorodecidua constitute a selective barrier separating two distinct environments, maternal and fetal. These tissues have the function of delimiting the amniotic cavity. Their histological complexity gives them physical, mechanical, and immunological properties to protect the fetus. Although the study of the amnion, chorion, and decidua separately provides knowledge about the functions of the fetal membranes, the protocol we describe in this chapter has the advantage of maintaining the biological and functional complexity of these tissues. In addition, this experimental model allows the researcher to recreate various pathological scenarios because this model allows for differential stimulation of the amnion or choriodecidua.

Dehydrated human amnion/chorion membrane to treat venous leg ulcers: a cost-effectiveness analysis.

OBJECTIVE: To evaluate the cost-effectiveness of dehydrated human amnion/chorion membrane (DHACM) in Medicare enrolees who developed a venous leg ulcer (VLU). METHOD: This economic evaluation used a four-state Markov model to simulate the disease progression of VLUs for patients receiving advanced treatment (AT) with DHACM or no advanced treatment (NAT) over a three-year time horizon from a US Medicare perspective. DHACM treatments were assessed when following parameters for use (FPFU), whereby applications were initiated 30-45 days after the initial VLU diagnosis claim, and reapplications occurred on a weekly to biweekly basis until completion of the treatment episode. The cohort was modelled on the claims of 530,220 Medicare enrolees who developed a VLU between 2015-2019. Direct medical costs, quality-adjusted life years (QALYs), and the net monetary benefit (NMB) at a willingness-to-pay threshold of $100,000/QALY were applied. Univariate and probabilistic sensitivity analyses (PSA) were performed to test the uncertainty of model results. RESULTS: DHACM applied FPFU dominated NAT, yielding a lower per-patient cost of $170 and an increase of 0.010 QALYs over three years. The resulting NMB was $1178 per patient in favour of DHACM FPFU over the same time horizon. The rate of VLU recurrence had a notable impact on model uncertainty. In the PSA, DHACM FPFU was cost-effective in 63.01% of simulations at the $100,000/QALY threshold. CONCLUSION: In this analysis, DHACM FPFU was the dominant strategy compared to NAT, as it was cost-saving and generated a greater number of QALYs over three years from the US Medicare perspective. A companion VLU Medicare outcomes analysis revealed that patients who received AT with a cellular, acellular and matrix-like product (CAMP) compared to patients who received NAT had the best outcomes. Given the added clinical benefits to patients at lower cost, providers should recommend DHACM FPFU to patients with VLU who qualify. Decision-makers for public insurers (e.g., Medicare and Medicaid) and commercial payers should establish preferential formulary placement for reimbursement of DHACM to reduce budget impact and improve the long-term health of their patient populations dealing with these chronic wounds. DECLARATION OF INTEREST: Support for this analysis was provided by MiMedx Group, Inc., US. JLD, and RAF are employees of MiMedx Group, Inc. WHT, BH, PS, BGC and WVP were consultants to MiMedx Group, Inc. VD, AO, MRK, JAN, NW and GAM served on the MiMedx Group, Inc. Advisory Board. MRK and JAN served on a speaker's bureau. WVP declares personal fees and equity holdings from Stage Analytics, US.

Membrane inflammasome activation by choriodecidual Ureaplasma parvum infection without intra-amniotic infection in a Non-Human Primate model†.

Intrauterine infection is a significant cause of neonatal morbidity and mortality. Ureaplasma parvum is a microorganism commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms of early stage ascending reproductive tract infection remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes we utilized a non-human primate (NHP) model of choriodecidual U. parvum infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at ~105-112 days gestation and choriodecidual inoculation with U. parvum (105 CFU/mL, n =4) or sterile media (controls; n = 4) starting at 115-119 days, repeated at 5-day intervals until C-section at 136-140 days (term=167 days). The average inoculation to delivery interval was 21 days, and Ureaplasma infection of the amniotic fluid (AF) was undetectable in all animals. Choriodecidual Ureaplasma infection resulted in increased fetal membrane expression of MMP-9 and PTGS2, but did not result in preterm labor or increased concentrations of AF pro-inflammatory cytokines. However, membrane expression of inflammasome sensors, NLRP3, NLRC4, AIM2, and NOD2, and adaptor ASC (PYCARD) gene expression were significantly increased. Gene expression of IL-1ß, IL-18, IL-18R1  , CASPASE-1, and pro-CASPASE-1 protein increased with Ureaplasma infection. Downstream inflammatory genes MYD88 and NFκB (Nuclear factor kappa-light-chain-enhancer of activated B cells) were also significantly upregulated. These results demonstrate that choriodecidual Ureaplasma infection, can cause activation of inflammasome complexes and pathways associated with pPROM and preterm labor prior to microbes being detectable in the AF.

Preterm membranes are mechanically more resistant than term membranes.

OBJECTIVE: To compare the biomechanical properties of fetal preterm membranes (20 + 0 weeks to 30 + 0 weeks) to those of the term (37 + 0 to 41 + 0 weeks). METHOD: Amnion and chorion were manually separated and samples were cut to the required geometry. Rectangular samples with (mode 1) and without (uniaxial) a notch, were tested for tearing energy, critical elongation, and tangent stiffness. Suture retention and inter-suture distance testing investigated the effect of suture placement. RESULTS: From the 15 preterm and 10 term placentas studied, no notable differences were observed in uniaxial testing. Mode 1 fracture testing showed a difference in tearing energy between the preterm and term chorion (0.025 ± 0.005 vs. 0.017 ± 0.005 J/m-1 ; p = 0.027) but not in the amnion (0.030 ± 0.017 vs. 0.029 ± 0.009 J/m-1 ; p = 0.895). Both preterm amnion and chorion showed a higher critical elongation compared with term (1.229 ± 0.057 vs. 1.166 ± 0.046; p = 0.019 and 1.307 ± 0.049 vs. 1.218 ± 0.058; p = 0.012). Preterm amnion had a higher suture retention strength than its term counterpart (0.189 ± 0.065 vs. 0.121 ± 0.031 N; p = 0.023). In inter-suture distance tests, no significant interaction was observed beyond 3 mm, but the preterm chorion showed less interaction at 1-2 mm distances. CONCLUSION: Preterm membranes have equivalent or superior tensile properties to term membranes. The chorion appears to contribute to the mechanical integrity of fetal membranes, particularly in preterm stages.

Zebrafish prss59.1 is involved in chorion development.

The prss59.1 gene was identified as one of 11 genes that were highly upregulated during the induction of ovulation in zebrafish by using an in vivo ovulation assay. Previously, we conducted biochemical characterization of Prss59.1 and revealed it to be a trypsin-like proteolytic enzyme. In this study, we established a prss59.1 gene knockout strain using the CRISPR/Cas9 system. Phenotypic analysis of prss59.1 knockout fish showed that prss59.1 is associated with chorion elevation, a prominent event in egg activation during fertilization. The chorions of heterozygous and homozygous prss59.1 mutant zebrafish were smaller than those of the wild type. The results suggested that Prss59.1 is necessary for chorion expansion. The homozygous prss59.1 mutant strain, with a small chorion, showed an extremely low survival rate. Fiber-supported knob-like structures (KS) on the chorion showed an abnormal structure in prss59.1 mutants. Prss59.1 was detected in the KS on the chorion. The pores on the chorion were smaller in the prss59.1 mutants than in the wild type. Transmission electron microscopy (TEM) observations of the cross sections of the chorions showed abnormalities in the chorion structure in prss59.1 mutants. These results demonstrated that Prss59.1 is involved in chorion elevation and in proper formation of the chorion, which is necessary for embryo development.

Evaluation on the efficacy of processed hydrated and dehydrated amnion chorion membrane on the proliferation of periodontal ligament fibroblasts.

The purpose of the present study was to process and assess the effect of hydrated amnion chorion membrane and dehydrated amnion chorion membrane on proliferation of periodontal ligament (PDL) fibroblast cells. The amnion chorion membrane (ACM) from placenta of 18 systemically healthy patients was obtained from the Department of Obstetrics and Gynaecology. They were processed as hydrated and dehydrated based on different processing methods. The Periodontal ligament cells were obtained from periodontal ligament of freshly extracted premolars of systemically healthy patients, due to orthodontic reasons. The PDL cells were further cultured in laboratory and were exposed to hydrated and dehydrated amnion chorion membrane. The MTT assay was performed to assess the proliferation of PDL fibroblast cells after 24 and 48 h. The hydrated and dehydrated amnion chorion membrane showed proliferation of PDL fibroblasts after 24 and 48 h. The proliferation of PDL fibroblasts in hydrated (p = 0.043) and dehydrated (p = 0.050) amnion chorion membrane was statistically significant at the end of 24 and 48 h respectively. On inter-group comparison dehydrated ACM showed significant proliferation of PDL fibroblasts after 24 (p=0.014) and 48 h (p=0.019). Within the limits of the present study, it can be concluded: both hydrated and dehydrated amnion chorion membrane showed proliferationof PDL fibroblast cells. However, dehydrated ACM showed significant proliferation of PDL fibroblasts.

Anatomy of the fetal membranes: insights from spinning disk confocal microscopy.

PURPOSE: The fetal membranes are essential for the maintenance of pregnancy, and their integrity until parturition is critical for both fetal and maternal health. Preterm premature rupture of the membranes (pPROM) is known to be an indicator of preterm birth, but the underlying architectural and mechanical changes that lead to fetal membrane failure are not yet fully understood. The aim of this study was to gain new insights into the anatomy of the fetal membrane and to establish a tissue processing and staining protocol suitable for future prospective cohort studies. METHODS: In this proof of principle study, we collected fetal membranes from women undergoing vaginal delivery or cesarean section. Small membrane sections were then fixed, stained for nucleic acids, actin, and collagen using fluorescent probes, and subsequently imaged in three dimensions using a spinning disk confocal microscope. RESULTS: Four fetal membranes of different types were successfully processed and imaged after establishing a suitable protocol. Cellular and nuclear outlines are clearly visible in all cases, especially in the uppermost membrane layer. Focal membrane (micro) fractures could be identified in several samples. CONCLUSION: The presented method proves to be well suited to determine whether and how the occurrence of membrane (micro) fractures and cellular jamming correlate with the timing of membrane rupture and the mode of delivery. In future measurements, this method could be combined with mechanical probing techniques to compare optical and mechanical sample information.

Dehydrated human amnion/chorion membrane allograft with spongy layer to significantly improve the outcome of chronic non-healing wounds.

We investigated the healing effect of a new dehydrated amnion/chorion membrane with a spongy layer over a 30-month period in 32 patients with 53 chronic non-healing wounds of different aetiologies. Wounds with <40% surface reduction after 4 weeks of best wound treatment underwent weekly allograft application by a certified wound specialist based on national guidelines and a standardised protocol until complete healing or definite treatment interruption. The main outcome measure was the percentage of wound surface reduction from baseline calculated using digital planimetry follow-up photographs. Overall, 38 (71.7%) wounds presented a favourable outcome (70%-100% area reduction), with 35 (66%) completely healing over a median time of 77 days (range 29-350 days). Favourable outcomes were observed in 75% of traumatic wounds, surgical wounds, venous leg ulcers and pressure injuries, as well as in 50% of ischaemic wounds. Wounds being present <12 months were significantly more likely to have a favourable outcome than more long-standing wounds (χ2 = 7.799; p = 0.005; OR = 3.378; 95% CI, 1.410-8.092). Thus, treatment with dehydrated amnion/chorion membrane with a spongy layer improves the outcome of non-healing wounds of different aetiologies and, therefore, has to be considered early in the management of refractory wounds.

Unique Usages of Dehydrated Human Amnion Chorion Membrane Allografts in Dermatology.

Dehydrated human amnion chorion membrane (dHACM) allografts are synthetic skin substitutes derived from placental tissue. dHACM allografts are used for replacing lost or damaged dermal tissue, as they contain many of the components found within the extracellular matrix that are beneficial in wound healing. Common uses of dHACM allografts include the healing of diabetic and non-diabetic foot and leg ulcers, decubitus ulcers, and wounds following debridement. While these grafts have been proven to be beneficial in other disciplines of medicine, their potential for use in the field of dermatology is emerging. Current clinical cases and research have shown dHACM allografts to be beneficial in repairing damaged tissue due to dermatologic conditions. They could play a role in the treatment of conditions causing chronic wounds, including dermal scarring or loss, and the repair of fragile skin. Examples of dHACM allograft use in dermatology include cases of pyoderma gangrenosum, Netherton syndrome, and wound healing with Mohs micrographic surgery. This literature review explores the efficacy of using dHACM allografts for the treatment of healing wounds within the field of dermatology. J Drugs Dermatol. 2023;22(12):1228-1231. doi:10.36849/JDD.7115.

Retention of Key Characteristics of Unprocessed Chorion Tissue Resulting in a Robust Scaffold to Support Wound Healing.

Placental membranes have been widely studied and used clinically for wound care applications, but there is limited published information on the benefits of using the chorion membrane. The chorion membrane represents a promising source of placental-derived tissue to support wound healing, with its native composition of extracellular matrix (ECM) proteins and key regulatory proteins. This study examined the impact of hypothermic storage on the structure of chorion membrane, ECM content, and response to degradation in vitro. Hypothermically stored chorion membrane (HSCM) was further characterized for its proteomic content, and for its functionality as a scaffold for cell attachment and proliferation in vitro. HSCM retained the native ECM structure, composition, and integrity of native unprocessed chorion membrane and showed no differences in response to degradation in an in vitro wound model. HSCM retained key regulatory proteins previously shown to be present in placental membranes and promoted the attachment and proliferation of fibroblasts in vitro. These data support the fact that hypothermic storage does not significantly impact the structure and characteristics of the chorion membrane compared to unprocessed tissue or its functionality as a scaffold to support tissue growth.

Dehydrated human amnion/chorion membrane use in emergent craniectomies shows minimal dural adhesions.

Decompressive craniectomies (DCs) are routinely performed neurosurgical procedures to emergently treat increased intracranial pressure secondary to multiple aetiologies, such as subdural haematoma, epidural haematoma, or malignant oedema in the setting of acute infarction. The DC procedure typically induces epidural fibrosis post-cranial resection, resulting in adherence of the dura to both the brain internally and skin flap externally. This becomes especially problematic in the setting of skull flap replacement for cranioplasty as adherences can lead to bridging vein tear, damage to the underlying brain cortex, and other postoperative complications. Dural adjuvants, which can contribute to decreased rate of adherence formation, can thereby reduce both postoperative cranioplasty complications and operative duration. Dehydrated human amnion/chorion membrane (DHACM) allografts (AMNIOFIX, MIMEDX Group Inc., US) have been shown to reduce the rate of dural scar tissue formation in re-exploration of posterior lumbar interbody fusion operations which require entry into the epidural space. The purpose of this study was to evaluate whether or not the use of DHACM in the setting of emergent craniectomies decreased the rate of dural adhesion formation and subsequent cranioplasty complications. Patients (n=7) who underwent emergent craniectomy and intraoperative placement of DHACM were evaluated during replacement of either an autologous skull cap or a custom-made implant, at which point the degree of adhesions was qualitatively assessed. Placement of DHACM below and on top of the dura resulted in negligible adhesion being found during the defect exposure, and there were no intraoperative complications during cranioplasties. Reported estimated blood loss across the seven patients averaged 64.2ml, total operative time averaged 79.2 minutes, and time dedicated to exposing defect for bone flap placement was <3 minutes.

Factors influencing RNA yield from placenta tissue.

High yield and integrity of placental RNA are crucial for placental transcriptomics studies. We assessed the effects of time to placental collection post-delivery; tissue storage, amount and method used for extraction; mode of delivery; and tissue type on total RNA yield. The optimal protocol for RNA extraction from placental tissue includes cryofreezing of the sample upon collection and RNA extraction from 50 mg of tissue using TRIzol reagent. Decidua yielded highest RNA quantity/mg of tissue, followed by villous tissue and the chorion. Comparisons with murine kidney and HEK293T show lower placental RNA yield, likely due to highly dense and heterogeneous tissue make-up and potential high placental nuclease activity.

Ruptura prematura de membranas ovulares / Premature rupture of ovular membranes

La ruptura prematura de las membranas ovulares se define como la pérdida de la integridad del amnios y corion antes del inicio del trabajo de parto, afecta el 3 % de los embarazos, causa un tercio de los partos pretérminos, los cuales ocupan el 10,49 % de los nacimientos y es el origen de altos índices de morbimortalidad perinatal. En la actualidad, el manejo de esta patología se orienta principalmente en evitar los factores de riesgo, hacer un diagnóstico adecuado, determinar la edad gestacional en que ocurre, realizar el monitoreo exhaustivo del bienestar materno-fetal y en decidir el momento idóneo de finalización de la gestación para minimizar sus complicaciones. Debido a la compleja y lábil estructura histológica de las membranas ovulares, se ha dejado a un lado el tratamiento directo de la entidad el cual sería sellar o reparar el defecto en sí. En los últimos años, numerosos estudios y protocolos clínicos de prestigiosos centros asistenciales han servido como guía para el manejo de esta entidad, pero en muy pocos se observa una terapia destinada a la reparación de dichas membranas o en sellar tal defecto. Las evidencias científicas demuestran que la regeneración y reparación de las membranas es lenta y compleja y los tratamientos propuestos para reparar o sellar su defecto no han gozado de la aceptación científica para su aprobación, sin embargo, el uso del parche hemático transvaginal endocervical autólogo luce como una alternativa terapéutica prometedora(AU)

The premature rupture of the ovular membranes is defined as the loss of the integrity of the amnion and chorion before the on set of labor, affects 3% of pregnancies, causes athird of preterm births which occupy 10,49% of births and is the origin of high rates of perinatal morbidity and mortality. At present, the management of this pathology is mainly oriented towards avoiding risk factors, making an adequate diagnosis, determining the gestational age in which it occurs, carrying out exhaustive monitoring of maternal-fetal well-being and deciding the ideal moment to end the treatment. Pregnancy to minimizeits complications. Due to the complex and labile histological structure of the ovular membranes, the direct treatment of the entity has been set a side, which would be to seal or repairthe defect it self. In recent years, numerous studies and clinicalprotocols from prestigious health care centers have served as aguide for the management of this entity, but very few have observed a therapy aimed at repairing said membranes or sealing such a defect. Scientific evidence shows that the regeneration and repair of the membranes is slow and complex and the treatment sproposed to repair or seal their defect have not enjoyed scientific acceptance for their approval, how ever, the use of the autologous endocervical transvaginal blood patch looks like a promising therapeutic alternative(AU)

Isoperla riverae, a new stonefly species from the southeast Nearctic, with notes on sympatric species including the larval description of Isoperla lenati Szczytko & Kondratieff, 2015 (Plecoptera: Perlodidae).

Isoperla riverae sp. n. is described from the southeastern USA. The new species is proposed based on details of the adult habitus, male aedeagus, vesicle, female subgenital plate, ovum chorion, and larval habitus. Supporting data includes color images, scanning electron micrographs, genetic analysis of DNA barcodes, and comparative morphology of cognate species. The larva of Isoperla lenati Szczytko & Kondratieff, 2015 is also described supported by color images.

Methods of In Ovo and Ex Ovo Ostrich Embryo Culture with Observations on the Development and Maturation of the Chorioallantoic Membrane.

Culture of shell-free and windowed eggs for drug testing and other experiments has been perfected for smaller eggs such as those of chickens, where the developing blood vessels of the chorioallantoic membrane (CAM) become accessible for manipulative studies. However, due to the thickness and hardness of the ostrich egg shell, such techniques are not applicable. Using a tork craft mini rotary and a drill bit, we established windowed egg, in-shell-membrane windowed egg, and in-shell-membrane shell-free methods in the ostrich egg, depending on whether the shell membranes were retained or not. Concomitant study of the developing CAM revealed that at embryonic day 16 (E16), the three layers of the CAM were clearly delineated and at E25, the chorionic capillaries had fused with the epithelium while the CAM at E37 had reached maturity and the chorion and the allantois were both 3-4 times thicker and villous cavity (VC) and capillary-covering cells were well delineated. Both intussusceptive and sprouting angiogenesis were found to be the predominant modes of vascular growth in the ostrich CAM. Development and maturation of the ostrich CAM are similar to those of the well-studied chicken egg, albeit its incubation time being twice in duration.