Artificial intelligence in esophageal cancer diagnosis and treatment: where are we now?-a narrative review.

Background and Objective: Artificial intelligence (AI) use is becoming increasingly prevalent directly or indirectly in daily clinical practice, including esophageal cancer (EC) diagnosis and treatment. Although the limits of its adoption and their clinical benefits are still unknown, any physician related to EC patients' management should be aware of the status and future perspectives of AI use in their field. The purpose of this review is to summarize the existing literature regarding the role of AI in diagnosis and treatment of EC. We have focused on the aids AI entails in the management of this pathology and we have tried to offer an updated perspective to maximize current applications and to identify potential future uses of it. Methods: Data concerning AI applied to EC diagnosis and treatment is not limited, including direct (those specifically related to them) and indirect (those referring to other specialties as radiology or pathology), applications. However, the clinical relevance of the discussed and presented models is still unknown. We performed a research in PubMed of English and Spanish written studies from January 1970 to June 2022. Key Content and Findings: Information regarding the role of AI in EC diagnosis and treatment has increased exponentially in recent years. Several models, including different variables and features have been investigated and some of them internally and externally validated. However, the main challenge remains to apply and introduce all these data into clinical practice, and, as some of the discussed studies argue, if the models are able to enhance experienced endoscopists' judgement. Although AI use is increasing steadily in different medical specialties, the truth is, most of the time, the gap between model development and clinical implementation is not closed. Learning to understand the routinely application of AI, as well as future improvements, would lead to a broadened adoption. Conclusions: Physicians should be aware of the multiple current clinical uses of AI in EC diagnosis and treatment and should take part in their clinical application and future developments to enhance patient care.

“Optimal recovery” after colon cancer surgery in the elderly, a comparative cohort study: Conventional care vs. enhanced recovery vs. prehabilitation / “Recuperación óptima” tras cirugía por cáncer de colon en el paciente añoso. Resultados de un estudio de cohorte: Cuidados convencionales, Recuperación intensificada y programa de prehabilitación

Background: Colon cancer in elderly patients is an increasing problem due to its prevalence and progressive aging population. Prehabilitation has experienced a great grown in this field. Whether it is the best standard of care for these patients has not been elucidated yet. Methods: A retrospective comparative cohort study of three different standards of care for elderly colon cancer patients (>65 years) was conducted. A four-weeks trimodal prehabilitation program (PP), enhanced recovery program (ERP) and conventional care (CC) were compared. Global complications, major complications (Clavien-Dindo ≥ 3), reinterventions, mortality, readmission and length of stay were measured. Optimal recovery, defined as postoperative course without major complications, no mortality, hospital discharge before the fifth postoperative day and without readmission, was the primary outcome measure. The influence of standard of care in optimal recovery and postoperative outcomes was assessed with univariate and multivariate logistic regression models. Results: A total of 153 patients were included, 51 in each group. Mean age was 77.9 years. ASA Score distribution was different between groups (ASA III-IV: CC 56.9%, ERP 25.5%, PP 58.9%; p = 0.014). Optimal recovery rate was 55.6% (PP 54.9%, ERP 66.7%, CC 45.1%; p = 0.09). No differences were found in major complications (p = 0.2) nor reinterventions (p = 0.7). Uneventful recovery favors ERP and PP groups (p = 0.046 and p = 0.049 respectively). Conclusions: PP and ERP are safe and effective for older colon cancer patients. Fewer overall complications and readmissions happened in ERP and PP patients. Major complications were independent of the standard of care used. (AU)

Introducción: El cáncer de colon (CC) en pacientes de edad avanzada es un problema creciente por su prevalencia y envejecimiento progresivo de la población. La prehabilitación ha experimentado un gran crecimiento en este campo sin haberse dilucidado si es el mejor estándar de cuidados para estos pacientes. Métodos: Estudio retrospectivo comparativo de cohortes de tres estándares diferentes de cuidados para pacientes mayores de 65 años con CC. Se compararon un programa de prehabilitación (PP) trimodal de cuatro semanas, uno de recuperación intensificada (RI) y cuidados convencionales (CC). Se midieron complicaciones globales, complicaciones mayores (Clavien-Dindo ≥ 3), reintervenciones, mortalidad, reingresos y estancia hospitalaria. La recuperación óptima fue la medida de resultado primaria. La influencia del estándar de atención en la recuperación óptima y los resultados postoperatorios se evaluó con modelos de regresión logística univariante y multivariante. Resultados: Se incluyeron 153 pacientes, 51 por grupo. La edad media fue 77,9 años. La distribución del ASA fue diferente entre los grupos (ASA III–IV: CC 56,9%, RI 25,5%, PP 58,9%; p = 0,014). La tasa de recuperación óptima fue del 55,6% (PP 54,9%, RI 66,7%, CC 45,1%; p = 0,09). No se encontraron diferencias en complicaciones mayores (p = 0,2) ni reintervenciones (p = 0,7). La recuperación sin incidencias favorece a los grupos RI y PP (p = 0,046 y p = 0,049 respectivamente). Conclusiones: PP y RI son seguros y efectivos para pacientes mayores con CC. Las complicaciones generales y reingresos en pacientes con RI y PP fueron menores. Las complicaciones mayores resultaron independientes del estándar de cuidados utilizado. (AU)

"Optimal recovery" after colon cancer surgery in the elderly, a comparative cohort study: Conventional care vs. enhanced recovery vs. prehabilitation.

BACKGROUND: Colon cancer in elderly patients is an increasing problem due to its prevalence and progressive aging population. Prehabilitation has experienced a great grown in this field. Whether it is the best standard of care for these patients has not been elucidated yet. METHODS: A retrospective comparative cohort study of three different standards of care for elderly colon cancer patients (>65 years) was conducted. A four-weeks trimodal prehabilitation program (PP), enhanced recovery program (ERP) and conventional care (CC) were compared. Global complications, major complications (Clavien-Dindo ≥ 3), reinterventions, mortality, readmission and length of stay were measured. Optimal recovery, defined as postoperative course without major complications, no mortality, hospital discharge before the fifth postoperative day and without readmission, was the primary outcome measure. The influence of standard of care in optimal recovery and postoperative outcomes was assessed with univariate and multivariate logistic regression models. RESULTS: A total of 153 patients were included, 51 in each group. Mean age was 77.9 years. ASA Score distribution was different between groups (ASA III-IV: CC 56.9%, ERP 25.5%, PP 58.9%; p = 0.014). Optimal recovery rate was 55.6% (PP 54.9%, ERP 66.7%, CC 45.1%; p = 0.09). No differences were found in major complications (p = 0.2) nor reinterventions (p = 0.7). Uneventful recovery favors ERP and PP groups (p = 0.046 and p = 0.049 respectively). CONCLUSIONS: PP and ERP are safe and effective for older colon cancer patients. Fewer overall complications and readmissions happened in ERP and PP patients. Major complications were independent of the standard of care used.

Multimodal Management of Fecal Incontinence Focused on Sphincteroplasty: Long-Term Outcomes from a Single Center Case Series.

The management of patients with fecal incontinence and an external anal sphincter (EAS) defect remains controversial. A retrospective series of overlapping anal sphincteroplasties performed between 1985−2013 from a single center, supplemented by selective puborectalis plication and internal anal sphincter repair is presented. Patients were clinically followed along with anorectal manometry, continence scoring (Cleveland Clinic Incontinence Score­CCS) and patient satisfaction scales. Patients with a suboptimal outcome were managed with combinations of biofeedback therapy (BFT), peripheral tibial nerve stimulation (PTNS), sacral nerve stimulation (SNS) or repeat sphincteroplasty. There were 120 anterior sphincter repairs with 90 (75%) levatorplasties and 84 (70%) IAS repairs. Over a median follow-up of 120 months (IQR 60−173.7 months) there were significant improvements in the recorded CCIS values (90.8% with a preoperative CCIS > 15 vs. 2.5% postoperatively; p < 0.001). There were 42 patients who required ancillary treatment with four repeat sphincteroplasties, 35 patients undergoing biofeedback therapy, 10 patients treated with PTNS and three managed with SNS implants with an ultimate good functional outcome in 92.9% of cases. No difference was noted in ultimate functional outcome between those treated with sphincteroplasty alone compared with those who needed ancillary treatments (97.1% vs. 85.7%, respectively). Overall, 93.3% considered the outcome as either good or excellent. Long-term functional outcomes of an overlapping sphincteroplasty are good. If the initial outcome is suboptimal, response to ancillary treatments remains good and patients are not compromised by a first-up uncomplicated sphincter repair.

Surgical Risk Following Anatomic Lung Resection in Thoracic Surgery: A Prediction Model Derived from a Spanish Multicenter Database. / Riesgo quirúrgico tras resección pulmonar anatómica en cirugía torácica. Modelo predictivo a partir de una base de datos nacional multicéntrica.

INTRODUCTION: The aim of this study was to develop a surgical risk prediction model in patients undergoing anatomic lung resections from the registry of the Spanish Video-Assisted Thoracic Surgery Group (GEVATS). METHODS: Data were collected from 3,533 patients undergoing anatomic lung resection for any diagnosis between December 20, 2016 and March 20, 2018. We defined a combined outcome variable: death or Clavien Dindo grade IV complication at 90 days after surgery. Univariate and multivariate analyses were performed by logistic regression. Internal validation of the model was performed using resampling techniques. RESULTS: The incidence of the outcome variable was 4.29% (95% CI 3.6-4.9). The variables remaining in the final logistic model were: age, sex, previous lung cancer resection, dyspnea (mMRC), right pneumonectomy, and ppo DLCO. The performance parameters of the model adjusted by resampling were: C-statistic 0.712 (95% CI 0.648-0.750), Brier score 0.042 and bootstrap shrinkage 0.854. CONCLUSIONS: The risk prediction model obtained from the GEVATS database is a simple, valid, and reliable model that is a useful tool for establishing the risk of a patient undergoing anatomic lung resection.

Pilot Trial of Extended Hypothermic Lung Preservation to Analyze Ischemia-reperfusion Injury in Pigs / Ensayo piloto de conservación pulmonar hipotérmica prolongada para analizar la lesión de isquemia-reperfusión en cerdos

Background: In lung transplantation (LT), the length of ischemia time is controversial as it was arbitrarily stablished. We ought to explore the impact of extended cold-ischemia time (CIT) on ischemia-reperfusion injury in an experimental model. Methods: Experimental, randomized pilot trial of parallel groups and final blind analysis using a swine model of LT. Donor animals (n=8) were submitted to organ procurement. Lungs were subjected to 6h (n=4) or 12h (n=4) aerobic hypothermic preservation. The left lung was transplanted and re-perfused for 4h. Lung biopsies were obtained at (i) the beginning of CIT, (ii) the end of CIT, (iii) 30min after reperfusion, and (iv) 4h after reperfusion. Lung-grafts were histologically assessed by microscopic lung injury score and wet-to-dry ratio. Inflammatory response was measured by determination of inflammatory cytokines. Caspase-3 activity was determined as apoptosis marker. Results: We observed no differences on lung injury score or wet-to-dry ratio any given time between lungs subjected to 6h-CIT or 12h-CIT. IL-1β and IL6 showed an upward trend during reperfusion in both groups. TNF-α was peaked within 30min of reperfusion. IFN-γ was hardly detected. Caspase-3 immunoexpression was graded semiquantitatively by the percentage of stained cells. Twenty percent of apoptotic cells were observed 30min after reperfusion. (AU)

Antecedentes: En el trasplante de pulmón (TP), la duración del tiempo de isquemia es controvertida, ya que se estableció de forma arbitraria. Sería útil explorar el impacto del tiempo de isquemia fría (TIF) prolongado sobre la lesión de isquemia-reperfusión en un modelo experimental. Métodos: Ensayo piloto experimental aleatorizado de grupos paralelos y análisis ciego final utilizando un modelo de TP en cerdos. Se extrajeron los órganos de los animales donantes (n=8). Los pulmones se conservaron durante 6 horas (n=4) o 12 horas (n=4) en hipotermia aeróbica. El pulmón izquierdo se trasplantó y reperfundió durante 4 horas. Se obtuvieron biopsias de pulmón (i) al comienzo del TIF, (ii) al final del TIF, (iii) 30 minutos después de la reperfusión y (iv) 4 horas después de la reperfusión. Los injertos de pulmón se evaluaron histológicamente mediante la puntuación de daño histológico pulmonar y la relación de peso húmedo y peso seco. La respuesta inflamatoria se valoró mediante la determinación de citoquinas inflamatorias. Se determinó la actividad de caspasa-3 como marcador de apoptosis. Resultados: No observamos diferencias en la puntuación de daño histológico pulmonar o en la relación de peso húmedo y peso seco en un momento dado entre los pulmones sometidos a 6 h-TIF o 12 h-TIF. Las IL-1β e IL-6 mostraron una tendencia ascendente durante la reperfusión en ambos grupos. El TNF-α alcanzó su punto máximo dentro de los 30 minutos posteriores a la reperfusión. Apenas se detectó IFN-γ. La inmunoexpresión de caspasa-3 se clasificó semicuantitativamente por el porcentaje de células teñidas. Se observó un 20% de células apoptóticas 30 minutos después de la reperfusión. (AU)

Pilot Trial of Extended Hypothermic Lung Preservation to Analyze Ischemia-reperfusion Injury in Pigs.

BACKGROUND: In lung transplantation (LT), the length of ischemia time is controversial as it was arbitrarily stablished. We ought to explore the impact of extended cold-ischemia time (CIT) on ischemia-reperfusion injury in an experimental model. METHODS: Experimental, randomized pilot trial of parallel groups and final blind analysis using a swine model of LT. Donor animals (n=8) were submitted to organ procurement. Lungs were subjected to 6h (n=4) or 12h (n=4) aerobic hypothermic preservation. The left lung was transplanted and re-perfused for 4h. Lung biopsies were obtained at (i) the beginning of CIT, (ii) the end of CIT, (iii) 30min after reperfusion, and (iv) 4h after reperfusion. Lung-grafts were histologically assessed by microscopic lung injury score and wet-to-dry ratio. Inflammatory response was measured by determination of inflammatory cytokines. Caspase-3 activity was determined as apoptosis marker. RESULTS: We observed no differences on lung injury score or wet-to-dry ratio any given time between lungs subjected to 6h-CIT or 12h-CIT. IL-1ß and IL6 showed an upward trend during reperfusion in both groups. TNF-α was peaked within 30min of reperfusion. IFN-γ was hardly detected. Caspase-3 immunoexpression was graded semiquantitatively by the percentage of stained cells. Twenty percent of apoptotic cells were observed 30min after reperfusion. CONCLUSIONS: We observed that 6 and 12h of CIT were equivalent in terms of microscopic lung injury, inflammatory profile and apoptosis in a LT swine model. The extent of lung injury measured by microscopic lung injury score, proinflammatory cytokines and caspase-3 determination was mild.

Pilot Trial of Extended Hypothermic Lung Preservation to Analyze Ischemia-reperfusion Injury in Pigs.

BACKGROUND: In lung transplantation (LT), the length of ischemia time is controversial as it was arbitrarily stablished. We ought to explore the impact of extended cold-ischemia time (CIT) on ischemia-reperfusion injury in an experimental model. METHODS: Experimental, randomized pilot trial of parallel groups and final blind analysis using a swine model of LT. Donor animals (n=8) were submitted to organ procurement. Lungs were subjected to 6h (n=4) or 12h (n=4) aerobic hypothermic preservation. The left lung was transplanted and re-perfused for 4h. Lung biopsies were obtained at (i) the beginning of CIT, (ii) the end of CIT, (iii) 30min after reperfusion, and (iv) 4h after reperfusion. Lung-grafts were histologically assessed by microscopic lung injury score and wet-to-dry ratio. Inflammatory response was measured by determination of inflammatory cytokines. Caspase-3 activity was determined as apoptosis marker. RESULTS: We observed no differences on lung injury score or wet-to-dry ratio any given time between lungs subjected to 6h-CIT or 12h-CIT. IL-1ß and IL6 showed an upward trend during reperfusion in both groups. TNF-α was peaked within 30min of reperfusion. IFN-γ was hardly detected. Caspase-3 immunoexpression was graded semiquantitatively by the percentage of stained cells. Twenty percent of apoptotic cells were observed 30min after reperfusion. CONCLUSIONS: We observed that 6 and 12h of CIT were equivalent in terms of microscopic lung injury, inflammatory profile and apoptosis in a LT swine model. The extent of lung injury measured by microscopic lung injury score, proinflammatory cytokines and caspase-3 determination was mild.

Spanish Video-Assisted Thoracic Surgery Group: Method, Auditing, and Initial Results From a National Prospective Cohort of Patients Receiving Anatomical Lung Resections / Grupo Español de Cirugía Torácica Videoasistida: Método, Auditoría y Resultados Iniciales de una Cohorte Nacional Prospectiva de Pacientes Tratados con Resección Pulmonar Anatómica

INTRODUCTION: Our study sought to know the current implementation of video-assisted thoracoscopic surgery (VATS) for anatomical lung resections in Spain. We present our initial results and describe the auditing systems developed by the Spanish VATS Group (GEVATS). METHODS: We conducted a prospective multicentre cohort study that included patients receiving anatomical lung resections between 12/20/2016 and 03/20/2018. The main quality controls consisted of determining the recruitment rate of each centre and the accuracy of the perioperative data collected based on six key variables. The implications of a low recruitment rate were analysed for "90-day mortality" and "Grade IIIb-V complications". RESULTS: The series was composed of 3533 cases (1917 VATS; 54.3%) across 33 departments. The centres' median recruitment rate was 99% (25-75th:76-100%), with an overall recruitment rate of 83% and a data accuracy of 98%. We were unable to demonstrate a significant association between the recruitment rate and the risk of morbidity/mortality, but a trend was found in the unadjusted analysis for those centres with recruitment rates lower than 80% (centres with 95-100% rates as reference): grade IIIb-V OR = 0.61 (p = 0.081), 90-day mortality OR = 0.46 (p = 0.051). CONCLUSIONS: More than half of the anatomical lung resections in Spain are performed via VATS. According to our results, the centre's recruitment rate and its potential implications due to selection bias, should deserve further attention by the main voluntary multicentre studies of our speciality. The high representativeness as well as the reliability of the GEVATS data constitute a fundamental point of departure for this nationwide cohort

INTRODUCCIÓN: Nuestro estudio buscó conocer el grado de implementación actual de la cirugía toracoscópica asistida por video (VATS, por sus siglas en inglés) para las resecciones pulmonares anatómicas en España. Presentamos nuestros resultados iniciales y describimos los sistemas de auditoría desarrollados por el grupo español de VATS (GEVATS). MÉTODOS: Realizamos un estudio de cohortes prospectivo multicéntrico que incluyó pacientes que fueron tratados con resecciones pulmonares anatómicas entre el 20/12/2016 y el 20/03/2018. Los controles de calidad principales consistieron en determinar la tasa de reclutamiento de cada centro y la precisión de los datos perioperatorios recolectados en base a seis variables clave. Se analizaron las implicaciones de una baja tasa de reclutamiento para "mortalidad a los 90 días" y "complicaciones de grado IIIb-V". RESULTADOS: La serie estaba compuesta por 3533 casos (1917 VATS; 54,3%) en 33 servicios. La mediana de la tasa de reclutamiento de los centros fue del 99% (p25-p75: 76-100%), con una tasa de reclutamiento global del 83% y una precisión de los datos del 98%. No pudimos demostrar una asociación significativa entre la tasa de reclutamiento y el riesgo de morbi-mortalidad, pero se encontró una tendencia en el análisis no ajustado para aquellos centros con tasas de reclutamiento inferiores al 80% (usando los centros con tasas de 95-100% como referencia): OR = 0,61 para el grado IIIb-V (p = 0,081), OR = 0,46 para la mortalidad a los 90 días (p = 0,051). CONCLUSIONES: Más de la mitad de las resecciones pulmonares anatómicas en España se realizan a través de VATS. Según nuestros resultados, la tasa de reclutamiento del centro y sus posibles implicaciones debido al sesgo de selección, deberían recibir más atención por parte de los principales estudios multicéntricos voluntarios de nuestra especialidad. La alta representatividad y la confiabilidad de los datos de GEVATS constituyen un punto de partida fundamental para esta cohorte nacional

Spanish Video-Assisted Thoracic Surgery Group: Method, Auditing, and Initial Results From a National Prospective Cohort of Patients Receiving Anatomical Lung Resections.

INTRODUCTION: Our study sought to know the current implementation of video-assisted thoracoscopic surgery (VATS) for anatomical lung resections in Spain. We present our initial results and describe the auditing systems developed by the Spanish VATS Group (GEVATS). METHODS: We conducted a prospective multicentre cohort study that included patients receiving anatomical lung resections between 12/20/2016 and 03/20/2018. The main quality controls consisted of determining the recruitment rate of each centre and the accuracy of the perioperative data collected based on six key variables. The implications of a low recruitment rate were analysed for "90-day mortality" and "Grade IIIb-V complications". RESULTS: The series was composed of 3533 cases (1917 VATS; 54.3%) across 33 departments. The centres' median recruitment rate was 99% (25-75th:76-100%), with an overall recruitment rate of 83% and a data accuracy of 98%. We were unable to demonstrate a significant association between the recruitment rate and the risk of morbidity/mortality, but a trend was found in the unadjusted analysis for those centres with recruitment rates lower than 80% (centres with 95-100% rates as reference): grade IIIb-V OR=0.61 (p=0.081), 90-day mortality OR=0.46 (p=0.051). CONCLUSIONS: More than half of the anatomical lung resections in Spain are performed via VATS. According to our results, the centre's recruitment rate and its potential implications due to selection bias, should deserve further attention by the main voluntary multicentre studies of our speciality. The high representativeness as well as the reliability of the GEVATS data constitute a fundamental point of departure for this nationwide cohort.

Completion pneumonectomy: a valuable option for lung cancer recurrence or new primaries.

BACKGROUND: The preoperative selection of patients with lung cancer recurrence remains a major clinical challenge. Several aspects of this kind of surgery are still insufficiently evidence-based, with only a few series with more than 50 patients. METHODS: A retrospective study on 29 patients who underwent a completion pneumonectomy for postoperative lung cancer recurrence or new primary was done in the period between October 2004 and December 2015. Inclusion criteria include complete (R0) first and second resections, histologically proven recurrent or new malignancy, complete pathohistological report after both operations, and exact data about the treatment outcome at the time of the last contact with patients or their families. RESULTS: There were 25 (86.2%) males and 4 (13.8%) females (M:F 6.2:1). In 13/29 patients, the interval between the first and second operations was less than 2 years, while in the remaining 16 patients, it was longer than 2 years. Concerning the operative stage distribution, stage I was more frequent after the first operation (44.8 vs. 22%), while stage III was dominant after the second operation (40.7 vs. 10.3%). The same tumor histology after the first and second operations existed in 24 (82.8%) patients. Adjuvant treatment was given to 53.6% of patients after the first and to 45.5% of patients after the second operation. The overall 5-year survival was 30%, median survival being 35 ± 16.9 months (1.896, 68.104 95% CI). A median survival of patients in post-surgery stage I after re-do surgery was better in comparison with that in higher stages (35 ± 22.6 vs.17.2 ± 15.1 vs. 21 ± 6.7 months, p > 0.05). Patients with the same tumor type at both operations lived significantly longer (median survival 48 ± 21.5 vs. 7.7 ± 1.9 months) than patients with different tumor histology after the second operation. Patients under 60 years (42.9%) lived longer than patients older than 60 years (median survival 69 ± 4.5 vs. 17.2 ± 14.3 months). The Cox regression analysis revealed only the disease stage at first operation and the same/different tumor histology as significant prognostic factors. One patient died from cardiac insufficiency caused by bronchopleural fistula (3.4% operative mortality). Operative morbidity was 34.4%. CONCLUSION: Completion pneumonectomy may be a reasonable option for postoperative lung cancer recurrence or new primaries only in carefully selected patients, in whom the potential oncological benefits overweigh the surgical risk.

Osteomielitis esternal y mediastinitis por Fusobacterium necrophorum / Sternal osteomyelitis and mediastinitis due to Fusobacterium necrophorum

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Investigating the use of primary adult subventricular zone neural precursor cells for neuronal replacement therapies.

With the relatively recent discovery that neurogenesis persists throughout life in restricted regions of the adult mammalian brain, including those of human beings, there has been great interest in the use of adult-derived neural stem cells for neuronal replacement. There are many great hurdles that must be overcome in order for such replacement strategies to succeed. In this review, we outline some of these hurdles and discuss recent experiments that investigate the potential of using neural precursor cells found in the subventricular zone of the adult brain for brain repair.

The proliferative ventricular zone in adult vertebrates: a comparative study using reptiles, birds, and mammals.

Although evidence accumulated during the last decades has advanced our understanding of adult neurogenesis in the vertebrate brain, many aspects of this intriguing phenomenon remain controversial. Here we review the organization and cellular composition of the ventricular wall of reptiles, birds, and mammals in an effort to identify differences and commonalities among these vertebrate classes. Three major cell types have been identified in the ventricular zone of reptiles and birds: migrating (Type A) cells, radial glial (Type B) cells, and ependymal (Type E) cells. Cells similar anatomically and functionally to Types A, B, and E have also been described in the ventricular wall of mammals, which contains an additional cell type (Type C) not found in reptiles or birds. The bulk of the evidence points to a role of Type B cells as primary neural precursors (stem cells) in the three classes of living amniotic vertebrates. This finding may have implications for the development of strategies for the possible treatment of human neurological disorders.