Revascularization of human ovarian grafts is equally efficient from both sides of the cortex tissue.

RESEARCH QUESTION: Does revascularization of human ovarian grafts in a mouse model occur with equal efficiency from both sides of the cortex tissue? DESIGN: Twenty-four frozen-thawed ovarian cortex pieces from 12 women were transplanted to immunodeficient mice, for 8 days to analyse graft revascularization using immunohistochemical detection of murine CD31, or for 8 weeks to evaluate follicle density (follicles/mm3). The CD31-positive vessel area and density were quantified using a custom-designed application. Three regions of interest (ROI) were defined in each tissue section: the cortical side, the centre and the medullary side. Vessels were subdivided into three categories according to size: microvessels (<300 µm2), small vessels (300-1000 µm2) and large vessels (>1000-3000 µm2). RESULTS: No significant difference in the mean percentage of the CD31-positive vessel area was found between the three ROI (cortical side: 3.9% ± 0.2%; centre: 3.5% ± 0.2%; medullary side: 4.0% ± 0.3%; P = 0.17), but a significantly lower density of vessels was found in the centre of the human ovarian grafts compared with the cortical and medullary sides (cortical side: 323 ± 14 vessels/mm2; centre: 240 ± 12 vessels/mm2; medullary side: 301 ± 18 vessels/mm2; P < 0.001). Microvessels comprised 89-91% of all vessels in the three ROI. Follicle density in ungrafted cortex pieces was 51.8 ± 17.3 and 14.7 ± 3.7 follicles/mm3 after 8 weeks of xenografting, resulting in a follicle survival rate of 28%. CONCLUSIONS: Host revascularization was established equally efficiently from both sides of transplanted human ovarian cortex, suggesting that transplantation techniques ensuring revascularization from both sides of the ovarian graft could potentially facilitate faster graft revascularization.

Hippo signaling, actin polymerization, and follicle activation in fragmented human ovarian cortex.

The Hippo pathway has been associated with regulation of early follicle growth. Studies of murine ovaries suggest that changes in the actin cytoskeleton, caused by fragmentation, result in inhibition of the Hippo pathway, and in turn, may activate follicle growth. In humans, the connections between fragmentation, the actin cytoskeleton, and follicle activation are yet to be confirmed. In this study, we investigated the impact in vitro fragmentation of a human ovarian cortex on (a) actin polymerization, (b) components of the Hippo pathway, and (c) follicle growth in vivo. The results showed that the ratio between globular and filamentous actin remained unchanged at all timepoints (0, 10, 30, 60, 120, and 240 min) following tissue fragmentation. Neither was the Hippo pathway effector protein YES-associated protein upregulated nor was gene expression of the downstream growth factors CCN2, CCN3, or CCN5 increased at any timepoint in the fragmented cortex. Furthermore, the number of growing follicles was similar in fragmented and intact cortex pieces after 6 weeks' xenotransplantation. However, the total number of surviving follicles was considerably lower in the fragmented cortex compared with intact tissue, suggesting detrimental effects of fragmentation on tissue grafting. These results indicate that fragmentation is likely to be ineffective to activate follicle growth in the human ovarian cortex.

COVID-19 and assisted reproductive technology services: repercussions for patients and proposal for individualized clinical management.

The prolonged lockdown of health services providing high-complexity fertility treatments -as currently recommended by many reproductive medicine entities- is detrimental for society as a whole, and infertility patients in particular. Globally, approximately 0.3% of all infants born every year are conceived using assisted reproductive technology (ART) treatments. By contrast, the total number of COVID-19 deaths reported so far represents approximately 1.0% of the total deaths expected to occur worldwide over the first three months of the current year. It seems, therefore, that the number of infants expected to be conceived and born -but who will not be so due to the lockdown of infertility services- might be as significant as the total number of deaths attributed to the COVID-19 pandemic. We herein propose remedies that include a prognostic-stratification of more vulnerable infertility cases in order to plan a progressive restart of worldwide fertility treatments. At a time when preventing complications and limiting burdens for national health systems represent relevant issues, our viewpoint might help competent authorities and health care providers to identify patients who should be prioritized for the continuation of fertility care in a safe environment.

Diving into the oocyte pool.

PURPOSE OF REVIEW: The ovarian reserve comprises an enormous surplus of follicles. Despite this, some women produce insufficient numbers of oocytes by conventional fertility treatments. However, recent technical accomplishments may transform assisted reproductive technology (ART) in such a way that oocytes are not necessarily the limiting factor. In this review, we present possible new strategies for enhancing the quantity of mature oocytes, and current views on autologous oocytes as potential sources of mitochondria to lift performance of compromised oocytes. RECENT FINDINGS: New discoveries of the signaling pathways activating dormant follicles and breakthroughs in techniques for autologous transfer of mitochondria have opened new doors to unexploited sources of oocytes and attractive ways of revitalizing oocytes. Extended numbers of mature oocytes may be obtained by in-vitro activation of dormant follicles in cortical biopsies or in-vitro maturation of immature oocytes during the natural or stimulated cycle, and used directly for fertility treatment or as a source of autologous mitochondria. SUMMARY: New approaches utilizing the abundant resources of immature oocytes combined with techniques for revitalizing deficient oocytes may transform ART, and potentially enhance both quantity and quality of fertilizable oocytes; hereby augmenting the pregnancy potential of women with poor reproductive performance.

Cancer and fertility preservation: international recommendations from an expert meeting.

In the last years, thanks to the improvement in the prognosis of cancer patients, a growing attention has been given to the fertility issues. International guidelines on fertility preservation in cancer patients recommend that physicians discuss, as early as possible, with all patients of reproductive age their risk of infertility from the disease and/or treatment and their interest in having children after cancer, and help with informed fertility preservation decisions. As recommended by the American Society of Clinical Oncology and the European Society for Medical Oncology, sperm cryopreservation and embryo/oocyte cryopreservation are standard strategies for fertility preservations in male and female patients, respectively; other strategies (e.g. pharmacological protection of the gonads and gonadal tissue cryopreservation) are considered experimental techniques. However, since then, new data have become available, and several issues in this field are still controversial and should be addressed by both patients and their treating physicians.In April 2015, physicians with expertise in the field of fertility preservation in cancer patients from several European countries were invited in Genova (Italy) to participate in a workshop on the topic of "cancer and fertility preservation". A total of ten controversial issues were discussed at the conference. Experts were asked to present an up-to-date review of the literature published on these topics and the presentation of own unpublished data was encouraged. On the basis of the data presented, as well as the expertise of the invited speakers, a total of ten recommendations were discussed and prepared with the aim to help physicians in counseling their young patients interested in fertility preservation.Although there is a great interest in this field, due to the lack of large prospective cohort studies and randomized trials on these topics, the level of evidence is not higher than 3 for most of the recommendations highlighting the need of further research efforts in many areas of this field. The participation to the ongoing registries and prospective studies is crucial to acquire more robust information in order to provide evidence-based recommendations.

The proteolytic activity of pregnancy-associated plasma protein-A is potentially regulated by stanniocalcin-1 and -2 during human ovarian follicle development.

STUDY QUESTION: Is the proteolytic activity of pregnancy-associated plasma protein-A (PAPP-A) regulated by the stanniocalcins (STC1 and STC2) during human follicle maturation? SUMMARY ANSWER: The STCs and PAPP-A show similar expression by immunohistochemistry in developing follicles, and regulation of PAPP-A proteolytic activity is suggested by the identification of inhibited protein complexes between PAPP-A and STC1 or STC2 in human follicular fluid (FF). WHAT IS KNOWN ALREADY: The insulin-like growth factor (IGF)-regulating proteinase PAPP-A is secreted by the granulosa cells of estrogen-dominant follicles and is involved in follicle growth. STC1 and STC2 have recently been identified as novel PAPP-A inhibitors, and their expression in non-human mammalian ovaries has previously been observed. STUDY DESIGN, SIZE, DURATION: The proteolytic activity of PAPP-A in human follicular fluid was assessed, and the interaction between PAPP-A and the STCs in human ovarian tissues and follicular fluid was analyzed using immunoassays. From 21 women, matched pairs of follicular fluid were obtained from one follicle just prior to final maturation of follicles with human chorionic gonadotrophin (hCG), and from another follicle in connection with oocyte aspiration after hCG treatment. Ovarian tissues were obtained from women having one ovary removed for fertility preservation by cryopreservation prior to gonadotoxic treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS: The concentration and activity of PAPP-A were determined in all samples of follicular fluid. Furthermore, to investigate PAPP-A regulation during follicle development, immunohistochemical staining of PAPP-A, STC1, and STC2 was performed on pre-antral and antral human follicles. To attempt the demonstration of native complexes between PAPP-A and the STCs, immunoprecipitation from a pool of human follicular fluid was performed. MAIN RESULTS AND THE ROLE OF CHANCE: The concentration of PAPP-A antigen in follicular fluid increased upon stimulation of ovulation with hCG (P < 0.02), but at the same time, PAPP-A activity was decreased. PAPP-A, STC1, and STC2 were localized together in primordial, late primary, and antral follicles, indicating that complex formation is possible in ovarian tissue. Covalent PAPP-A:STC2 and non-covalent PAPP-A:STC1 complexes were immunoprecipitated from follicular fluid, documenting for the first time native inhibited complexes between PAPP-A and the STCs. LIMITATIONS, REASONS FOR CAUTION: We have demonstrated the presence of native complexes between PAPP-A and the STCs in the human ovary, indicating STC-mediated PAPP-A proteolytic inhibition. Further investigation is required to extend this principle to other tissues. WIDER IMPLICATIONS OF THE FINDINGS: Our data suggest that the STCs contribute to PAPP-A regulation during folliculogenesis and support a general model in which STC1 and STC2 are regulators of mammalian IGF activity through inhibition of PAPP-A. We suggest that future functional studies take both PAPP-A and the STCs into consideration. STUDY FUNDING/COMPETING INTERESTS: This work was supported by grants from the Novo Nordisk Foundation, and the Danish Council for Independent Research. No competing interests declared.

Human steroidogenesis: implications for controlled ovarian stimulation with exogenous gonadotropins.

In the menstrual cycle, the mid-cycle surge of gonadotropins (both luteinising hormone [LH] and follicle-stimulating hormone [FSH]) signals the initiation of the periovulatory interval, during which the follicle augments progesterone production and begins to luteinise, ultimately leading to the rupture of the follicle wall and the release of an oocyte. The administration of gonadotropins in controlled ovarian stimulation (COS) leads to supraphysiological steroid concentrations of a very different profile compared with those seen during natural cycles. It has been suggested that these high steroid concentrations cause alterations in endometrial development, affecting oocyte viability in assisted reproductive technology. Furthermore, it has been proposed that elevated progesterone levels have a negative effect on the reproductive outcome of COS. This may arise from an asynchrony between embryo stage and endometrium status at the window of implantation. The regulation of progesterone production by the developing follicles during COS is a complicated interplay of hormonal systems involving the theca and granulosa cells, and the effect of the actions of both LH and FSH. The present paper reviews current knowledge of the regulation of progesterone in the human ovary during the follicular phase and highlights areas where knowledge remains limited. In this review, we provide in-depth information outlining the regulation and function of gonadotropins in the complicated area of steroidogenesis. Based on current evidence, it is not clear whether the high levels of progesterone produced during COS have detrimental effects on fertility.

Microdissection Testicular Sperm Extraction Versus Multiple Needle-pass Percutaneous Testicular Sperm Aspiration in Men with Nonobstructive Azoospermia: A Randomized Clinical Trial.

BACKGROUND: Surgical extraction of testicular spermatozoa is needed in men with nonobstructive azoospermia (NOA) who wish to become biological fathers. Based on available uncontrolled studies with unspecific patient selection, microdissection testicular sperm extraction (mTESE), having a sperm retrieval rate (SRR) of 50%, is considered the most efficient sperm retrieval procedure. However, no randomized clinical trials for comparison of different sperm retrieval procedures exist. Testicular sperm aspiration (TESA) is simple and commonly used, and we hypothesized that this technique using multiple needle passes would give similar SRRs to mTESE. OBJECTIVE: To compare mTESE and multiple needle-pass TESA in men with NOA. DESIGN, SETTING, AND PARTICIPANTS: A randomized clinical trial was performed between June 2017 and April 2021, with inclusion of 100 men with NOA from four centers in Denmark and Sweden. All participants received treatment at the same institution. INTERVENTION: Participants were randomized to mTESE (n = 49) or multiple needle-pass TESA (n = 51). Patients with failed multiple needle-pass TESA proceeded directly to salvage mTESE. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was SRR. Secondary outcomes included complications and changes in reproductive hormones after surgery. RESULTS AND LIMITATIONS: Spermatozoa were retrieved in 21/49 (43%) men after mTESE and in 11/51 (22%) men after multiple needle-pass TESA (rate difference -0.21; 95% confidence interval -0.39 to -0.03; p = 0.02). The combined SRR for multiple needle-pass TESA + salvage mTESE was 15/51 (29%). No complications occurred after multiple needle-pass TESA only, while 5/89 (6%) men having mTESE experienced a complication requiring surgical intervention. Overall, no statistically significant differences in reproductive hormones were observed between groups after 6 mo. Limitations include the low number of patients in secondary outcome data. CONCLUSIONS: In direct comparison, SRR was higher in mTESE than in multiple needle-pass TESA. PATIENT SUMMARY: Men with azoospermia need surgical extraction of spermatozoa to become biological fathers. In this randomized trial, we compared two surgeries (microdissection testicular sperm extraction [mTESE] and testicular sperm aspiration [TESA]) and found that mTESE gives a higher sperm retrieval rate than multiple needle-pass TESA.

Fertility preservation in boys facing gonadotoxic cancer therapy.

Patient survival following childhood cancer has increased with contemporary radiation and chemotherapy techniques. However, gonadotoxicity associated with treatments means that infertility is a common consequence in survivors. Novel fertility preservation options are emerging, but knowledge about these options amongst urologists and other medical professionals is lacking. Pre-pubertal boys generally do not produce haploid germ cells. Thus, strategies for fertility preservation require cryopreservation of tissue containing spermatogonial stem cells (SSCs). Few centres worldwide routinely offer this option and fertility restoration (including testicular tissue engraftment, autotransplantation of SSCs and in vitro maturation of SSCs to spermatozoa) post-thaw is experimental. In pubertal boys, the main option for fertility preservation is masturbation and cryopreservation of the ejaculate. Assisted ejaculation using penile vibratory stimulation or electroejaculation and surgical sperm retrieval can be used in a sequential manner after failed masturbation. Physicians should inform boys and parents about the gonadotoxic effects of cancer treatment and offer fertility preservation. Preclinical experience has identified challenges in pre-pubertal fertility preservation, but available options are expected to be successful when today's pre-pubertal boys with cancer become adults. By contrast, fertility preservation in pubertal boys is clinically proven and should be offered to all patients undergoing cancer treatment.

Legal termination of a pregnancy resulting from transplanted cryopreserved ovarian tissue.

Cryopreservation of ovarian tissue is a promising new technique for fertility preservation in patients facing gonadotoxic treatment. Ovarian tissue is extracted and cryo-stored at low temperature prior to treatment. If the woman becomes menopausal, the tissue can be transplanted and a few months later the woman will start to ovulate and be able to conceive, naturally or with assisted reproduction treatment. Currently, 12 healthy children have been born worldwide as a result of transplanting frozen/thawed ovarian tissue. Of these children 3 are Danish and a number of other Danish women are currently attempting to become pregnant. One of these women conceived naturally and had a normal intrauterine pregnancy following transplantation of cryopreserved ovarian tissue. However, the woman decided to terminate the pregnancy within the legal time frame. This pregnancy imposes cryopreservation of ovarian tissue for fertility preservation as a valid method and illustrates that personal life circumstances may rapidly change.

Creating a Global Community of Practice for Oncofertility.

Fertility preservation in the cancer setting, known as oncofertility, is a field that requires cross-disciplinary interaction between physicians, basic scientists, clinical researchers, ethicists, lawyers, educators, and religious leaders. Funded by the National Institutes of Health, the Oncofertility Consortium (OC) was formed to be a scientifically grounded, transparent, and altruistic resource, both intellectual and monetary, for building this new field of practice capable of addressing the unique needs of young patients with cancer. The OC has expanded its attention to include other nonmalignant conditions that can threaten fertility, and the work of the OC now extends around the globe, involving partners who together have created a community of shared effort, resources, and practices. The OC creates materials that are translated, disseminated, and amended by all participants in the field, and local programs of excellence have developed worldwide to accelerate the pace and improve the quality of oncofertility research and practice. Here we review the global oncofertility programs and the capacity building activities that strengthen these research and clinical programs, ultimately improving patient care.

Parental Acceptance Rate of Testicular Tissue Cryopreservation in Danish Boys with Cryptorchidism.

Despite orchidopexy within the first year of life, 20-25% of boys with nonsyndromic cryptorchidism may risk infertility according to histological and hormonal data obtained during surgery. The aim of this study was to evaluate the acceptance rate of testicular tissue cryopreservation among parents of prepubertal boys with cryptorchidism. Fourteen boys with cryptorchidism and high infertility risk were offered cryopreservation as an additional procedure after orchidopexy based on abnormal histopathological findings at primary surgery, whereas 27 boys with bilateral cryptorchidism were offered cryopreservation at the initial orchidopexy. A total of 90% of parents (37/41, 13/14, and 24/27) gave consent to perform cryopreservation, despite being well-informed that the procedural efficacy is largely unproven and may only be needed in about 20% of cases. The number of germ cells per tubule cross-section was 0.03-1.70 (median 0.37) and 22 boys (54%, 22/41) had a value below the lower range. Twelve boys (29%, 12/41) had no type A dark spermatogonia in their biopsy. Cryopreservation of testicular tissue is the first step to introduce spermatogonial stem cell-based therapy into clinical male infertility treatment. At the time of orchidopexy, a testicular biopsy can be collected to ascertain the infertility risk, and it may be an option for boys with bilateral cryptorchidism to have spermatogonial stem cells frozen as a fertility reserve.

The POSEIDON Criteria and Its Measure of Success Through the Eyes of Clinicians and Embryologists.

This article represents a viewpoint on the POSEIDON criteria by a group of clinicians and embryologists. Its primary objective is to contextualize the Poseidon criteria and their metric of success for the relevant Frontiers Research Topic "POSEIDON's Stratification of Low Prognosis Patients in ART: The WHY, the WHAT, and the HOW". "Low prognosis" relates with reduced oocyte number, which can be associated with low or sometimes a normal ovarian reserve and is aggravated by advanced female age. These aspects will ultimately affect the number of embryos generated and consequently, the cumulative live birth rate. The novel system relies on female age, ovarian reserve markers, ovarian sensitivity to exogenous gonadotropin, and the number of oocytes retrieved, which will both identify the patients with low prognosis and stratify such patients into one of four groups of women with "expected" or "unexpected" impaired ovarian response to exogenous gonadotropin stimulation. Furthermore, the POSEIDON group introduced a new measure of clinical success in ART, namely, the ability to retrieve the number of oocytes needed to obtain at least one euploid blastocyst for transfer in each patient. Using the POSEIDON criteria, the clinician can firstly identify and classify patients who have low prognosis in ART, and secondly, aim at designing an individualized treatment plan to maximize the chances of achieving the POSEIDON measure of success in each of the four low prognosis groups. The novel POSEIDON classification system is anticipated to improve counseling and management of low prognosis patients undergoing ART, with an expected positive effect on reproductive success and a reduction in the time to live birth.

Cryopreservation of Ovarian Tissue: Opportunities Beyond Fertility Preservation and a Positive View Into the Future.

In current years, ovarian tissue cryopreservation (OTC) and transplantation is gaining ground as a successful method of preserving fertility in young women with primarily cancer diseases, hereby giving them a chance of becoming biological mothers later on. However, OTC preserves more than just the reproductive potential; it restores the ovarian endocrine function and thus the entire female reproductive cycle with natural levels of essential hormones. In a female population with an increased prevalence in the loss of ovarian function due to induced primary ovarian insufficiency (POI) and aging, there is now, a need to develop new treatments and provide new opportunities to utilize the enormous surplus of follicles that most females are born with and overcome major health issues associated with the lack of ovarian hormones. Cell/tissue-based hormone replacement therapy (cHRT) by the use of stored ovarian tissue could be one such option comprising both induction of puberty in prepubertal POI girls, treatment of POI and premature menopause, and as primary prevention at the onset of menopause. In the current review, we explore known and entirely new applications for the potential utilization of OTC including cHRT, social freezing, culture of immature oocytes, and a modern ovarian resection for women with polycystic ovaries, and discuss the indications hereof.

Successful pregnancy in a woman previously suffering from ß-thalassemia following transplantation of ovarian tissue cryopreserved before puberty.

Ovarian tissue removed from a 9-year-old girl suffering from thalassemia was kept deep-frozen for 14 years before being transplanted back to the now adult woman. Subsequently, she conceived following IVF treatment and delivered a healthy baby where the oocyte derived from the transplanted tissue. This is the first woman worldwide to have a baby where the ovarian tissue was frozen pre-pubertally and expand the therapeutic options for rare genetic diseases like thalassemia and girls who suffer from childhood cancer.

Temporal expression pattern of genes during the period of sex differentiation in human embryonic gonads.

The precise timing and sequence of changes in expression of key genes and proteins during human sex-differentiation and onset of steroidogenesis was evaluated by whole-genome expression in 67 first trimester human embryonic and fetal ovaries and testis and confirmed by qPCR and immunohistochemistry (IHC). SRY/SOX9 expression initiated in testis around day 40 pc, followed by initiation of AMH and steroidogenic genes required for androgen production at day 53 pc. In ovaries, gene expression of RSPO1, LIN28, FOXL2, WNT2B, and ETV5, were significantly higher than in testis, whereas GLI1 was significantly higher in testis than ovaries. Gene expression was confirmed by IHC for GAGE, SOX9, AMH, CYP17A1, LIN28, WNT2B, ETV5 and GLI1. Gene expression was not associated with the maternal smoking habits. Collectively, a precise temporal determination of changes in expression of key genes involved in human sex-differentiation is defined, with identification of new genes of potential importance.

Creating a Global Community of Practice for Oncofertility.

Fertility preservation in the cancer setting, known as oncofertility, is a field that requires cross-disciplinary interaction between physicians, basic scientists, clinical researchers, ethicists, lawyers, educators, and religious leaders. Funded by the National Institutes of Health, the Oncofertility Consortium (OC) was formed to be a scientifically grounded, transparent, and altruistic resource, both intellectual and monetary, for building this new field of practice capable of addressing the unique needs of young patients with cancer. The OC has expanded its attention to include other nonmalignant conditions that can threaten fertility, and the work of the OC now extends around the globe, involving partners who together have created a community of shared effort, resources, and practices. The OC creates materials that are translated, disseminated, and amended by all participants in the field, and local programs of excellence have developed worldwide to accelerate the pace and improve the quality of oncofertility research and practice. Here we review the global oncofertility programs and the capacity building activities that strengthen these research and clinical programs, ultimately improving patient care.

Ovarian volume throughout life: a validated normative model.

The measurement of ovarian volume has been shown to be a useful indirect indicator of the ovarian reserve in women of reproductive age, in the diagnosis and management of a number of disorders of puberty and adult reproductive function, and is under investigation as a screening tool for ovarian cancer. To date there is no normative model of ovarian volume throughout life. By searching the published literature for ovarian volume in healthy females, and using our own data from multiple sources (combined n=59,994) we have generated and robustly validated the first model of ovarian volume from conception to 82 years of age. This model shows that 69% of the variation in ovarian volume is due to age alone. We have shown that in the average case ovarian volume rises from 0.7 mL (95% CI 0.4-1.1 mL) at 2 years of age to a peak of 7.7 mL (95% CI 6.5-9.2 mL) at 20 years of age with a subsequent decline to about 2.8 mL (95% CI 2.7-2.9 mL) at the menopause and smaller volumes thereafter. Our model allows us to generate normal values and ranges for ovarian volume throughout life. This is the first validated normative model of ovarian volume from conception to old age; it will be of use in the diagnosis and management of a number of diverse gynaecological and reproductive conditions in females from birth to menopause and beyond.

Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery.

Human embryonic stem cells (hESCs) are potential therapeutic tools and models of human development. With a growing interest in primary cilia in signal transduction pathways that are crucial for embryological development and tissue differentiation and interest in mechanisms regulating human hESC differentiation, demonstrating the existence of primary cilia and the localization of signaling components in undifferentiated hESCs establishes a mechanistic basis for the regulation of hESC differentiation. Using electron microscopy (EM), immunofluorescence, and confocal microscopies, we show that primary cilia are present in three undifferentiated hESC lines. EM reveals the characteristic 9 + 0 axoneme. The number and length of cilia increase after serum starvation. Important components of the hedgehog (Hh) pathway, including smoothened, patched 1 (Ptc1), and Gli1 and 2, are present in the cilia. Stimulation of the pathway results in the concerted movement of Ptc1 out of, and smoothened into, the primary cilium as well as up-regulation of GLI1 and PTC1. These findings show that hESCs contain primary cilia associated with working Hh machinery.