Prevalence and morphometry of sternal and xiphoid foramen: a meta-analysis on 16,666 subjects.

PURPOSE: Sternal foramen is a perforation of the sternum that can be a source of misdiagnosis during radiographic imaging or life-threatening perforations during bone marrow sampling. The aim of this study was to conduct a meta-analysis on the prevalence, morphometrics, and location of foramen in the sternal body and xiphoid process, describe morphometric features of this phenomenon, and thus verify its clinical importance. Moreover, our secondary outcome was to compare effectiveness of various imaging methods in diagnosis of the sternal or xiphoid foramen. METHODS: A comprehensive search was conducted on major scientific databases to identify studies containing relevant information. Data on foramen's prevalence, location, morphometrics, and accompanying findings were extracted and pooled into a meta-analysis using MetaXL 5.0. RESULTS: Thirty-five studies (n = 16,666 subjects) were included. The overall pooled prevalence of a foramen in the sternal body and/or a xiphoid process was 8.9% (95% CI 6.5-11.7) and it equaled 6.5% (95% CI 5.6-7.6) for sternal body alone and 2.9% (95% CI 0.5-6.9) for the xiphoid process. The foramen was more prevalent in males than in females (12.2% vs. 6.8%). The prevalence of sternal foramen was higher in South American [13.9% (95% CI 11.2-16.9)] and African [13.6% (95% CI 9.7-18.0)] studies compared to North American [6.2% (95% CI 5.0-7.5)] and European populations [8.6% (95% CI 3.1-16.3)]. Mean transverse and vertical diameter of foramen equaled 4.7 mm (95% CI 3.8-5.5), and 5.6 mm (95% CI 4.2-6.9), respectively. CONCLUSION: Our analysis proves that the sternal foramina are structures of significant prevalence and size. Any physician should keep them in mind when performing punctures in this area.

Anatomical variations of the sternum: sternal foramen and variant xiphoid morphology in dried adult human sternum in Ethiopia.

Background: The sternum exhibits unique anatomical variations with major clinical and forensic implications. This study is devoted to providing baseline epidemiological information about the sternal foramen and variant xiphoid morphology in Ethiopia. Two extremely interesting and unusual variations of the sternal foramen are also discussed. Methods: This observational study was carried out using dried adult human sternum obtained from skeletal remains samples brought for medicolegal examination over a period of 4 years. A total of 94 dried adult human sternums (66 males (70.2%) and 28 females (29.8%)) were obtained with an age range of 21 to 57 years and a mean age at death of 38.383 ± 11.3480 years. Dried human sternum specimens were morphologically examined, and morphometric parameters were recorded and photographed. Results: A sternal foramen was found in 18 specimens (19.1%); 17 were male and one was female. A single sternal foramen was observed in 83.3% (n=15/18) of the sternal bodies and 11.1% (n=2/18) of the xiphoid processes (both males). In addition, a double sternal foramen was observed in a single male specimen on the mesosternum and xiphoid process. The most common sternal foramen site was at the fifth costochondral junction level. The xiphoid process was present in 77 samples and ended as a single process in 83.1% (n=64/77) of samples. In 15.6% (n=12/77) of the samples, the xiphoid process was bifurcated and trifurcated in a single male (1.3%) specimen. Conclusions: The sternal foramen and variation in xiphoid morphology are common anatomical variations in Ethiopia. The findings of the current study highlight the necessity of strict precautionary measures during sternal procedures in this study population. In addition, such incidental findings during radiologic and autopsy procedures should be properly evaluated to avoid misdiagnosis and misinterpretation of such findings as traumatic or pathologic conditions.

Prevalence of the sternalis muscle in a sample of routinely dissected human cadavers.

PURPOSE: Sternalis muscle is an uncommon muscle head attaching between the sternoclavicular joint superiorly and the costal cartilage near the xiphoid process. METHODS: In this study, 36 cadavers (18 male, 18 female) were obtained through the Anatomical Board of the State of Florida and complete, routine musculoskeletal dissection was performed while adhering to all relevant laws and practices. RESULTS: Two examples of the sternalis muscle belly (5%) were identified, one in a black male and one a white female. The sternalis muscles were bilateral in both cases and each was formed of a single muscle belly. The superior attachments were continuous with the sternal attachment of sternocleidomastoid, and the inferior attachments connected to the costal cartilages. Sternalis did not cross the midline and the T2-T5 anterior intercostal neurovasculature associated closely with the muscle belly. In the female, a well-formed unilateral chondrocoracoideus muscle was apparent with a branch from the medial pectoral nerve closely associated on the deep surface. No other abnormalities in the chest, axilla, or brachial plexus were noted on either cadaver, and the pectoralis major and minor muscles were normally formed and innervated in both cases. CONCLUSION: This study supports other evidence in the literature that indicates the sternalis muscle has an average prevalence in the population of approximately 5%, and it appears across race and sex. Education about this structure is important for radiologists, surgeons, and doctors of physical therapy that may be involved in treatment and post-surgical rehabilitation of this region.

Correlation of Xiphopubic Distance, Body Weight, Height and Body Mass Index with Intravesical and Abdominal Initial Resting Pressures in Urodynamic Testing in the Sitting Position.

OBJECTIVES: To compare the initial resting intravesical pressure (pves ) and abdominal pressure (pabd ) in the sitting position with the typical range of values, to assess the correlation between such pressures and patient xipho-pubic distance, body weight, height and body mass index (BMI), and to estimate if xipho-pubic distance can be a guide to interpret initial resting pressures in urodynamic testing. METHODS: Women with lower urinary tract symptomatology referred for urodynamic testing were consecutively enrolled in a prospective study. Conventional cystometry was done following "good urodynamic practices". The correlation between initial resting pves and pabd and xipho-pubic distance, body weight, height and BMI were studied using simple and multiple linear regression analysis. Statistical significance was defined as P < 0.05. RESULTS: One hundred women aged (mean ± SD) 59.2 ± 13.3 were studied. There was a significant correlation between both pves and pabd , and xipho-pubic distance, body weight and BMI and no correlation with height. Over the multiple analysis, xipho-pubic distance and body weight correlated independently with pves ; body weight correlated independently with pabd . Three patients had pves and/or pabd out of typical range, with BMIs values of 18.48, 18.72 and 35.81 kg/m2 . There was a wide range of difference between xipho-pubic distance and initial resting pressures. CONCLUSIONS: Out of range initial resting pressures occur in underweight (or close to) or severely obese patients. Xipho-pubic distance and body weight correlated independently with pves . Body weight correlated independently with pabd . Xipho-pubic distance cannot be a guide to interpret the initial resting pressures.

Clinical location of the fourth and fifth intercostal spaces as a percent of the length of the sternum.

OBJECTIVES: To verify accurate placement of the precordial ECG leads by identifying the 4th and 5th intercostal spaces as a function of the length of the sternum. This should decrease the percentage of lead misplacement leading to misdiagnoses. METHODS: The population consisted of patients and healthy volunteers. The proposed method compared palpation of the 4th and 5th intercostal spaces to a percentile of the sternal length. Location of the 4th and 5th intercostal space using a simple device was evaluated to assist in proper placement of the precordial leads to obtain accurate diagnosis. RESULTS: The location of the 4th and 5th intercostal space is related to the length of the sternum. It is 77% of the sternal length that measures 15cm for the 4th intercostal space. The position of the V1 and V2 electrodes decreases to 57% when the sternal length is 26cm. Similar data was obtained to locate the 5th intercostal space with proper position of V4-V6 electrodes. Tables are provided to facilitate this process. An instrument was designed to measure the 4th and 5th intercostal space as a function of the sternal length. CONCLUSIONS: The location of the 4th and 5th intercostal space is identified based on the length of the sternum.

Sternal foramina: incidence in Greek population, anatomy and clinical considerations.

PURPOSE: Sternal foramina represent developmental defects in the sternum, which occur due to incomplete fusion of the sternal ossification centers. Sternal foramina have been correlated with several clinical implications and constitute a subject of interest for the forensic practice. The aim of this study is to define their incidence in Greek population. METHODS: The presence of midline foramen was studied in 60 dried, adult sterna derived from the Anatomy Department of Medical School of Aristotle University of Thessaloniki. Measurements were made with a 0.01-mm accuracy caliber and photographic documentation was obtained. Additionally, computed tomography scanning of the sterna was performed. RESULTS: Sternal foramina were found in 11 subjects, resulting in an incidence of 18.3% over the total population. In 27.3% of the subjects with sternal foramen, a single sternal foramen was observed in the body of the sternum, while in 45.5% of the sterna presenting sternal foramina, multiple xiphoidal foramina were noticed. In two specimens, association of xiphoidal foramina with sternal cleft was documented. CONCLUSION: Sternal foramina are variant quite common in the population, with distinct imaging pattern and awareness of their existence is important for the physician.

Potential risk of malposition of nasogastric tube using nose-ear-xiphoid measurement.

BACKGROUND: Correct placement of nasogastric tubes provide proper functionality and maximize benefit and minimize risk. The Nose-Ear-Xiphoid (NEX) body surface estimate method is a long-lasting technique, and this study was conducted to evaluate the correlation between NEX method and the secure insertion depth of nasogastric tube. MATERIALS AND METHODS: Thirty patients with nasogastric tube insertion who received whole body positron emission tomography with computerized tomography scan (PET-CT) were recruited. All data were gathered in the image center, which included Nose-Ear (NE), Ear-Xiphoid (EX), Nose-Ear-Xiphoid (NEX), glabella-xiphoid (GX) and glabella-umbilicus (GU) lengths. The distances of the inserted portion of the nasogastric tube between the cardiac and the nostril were measured by multiplanar reconstruction algorithm. RESULTS: Only one patient successfully placed all side-holes into the stomach while using NEX method to estimate inserting depth. Twenty-nine patients (96.7%) failed to place correctly. Fourteen participants had one or more side-holes in both the esophagus and the stomach sides. Fifteen patients could not pass through any side-hole across the gastroesophageal junction. They had shorter EX distances (p = 0.02), but no difference among the NE distances. Body height had the highest statistical correlation with nasogastric tube length (adjusted R(2) = 0.459), as compared with the NEX, GX and GU body surface methods. CONCLUSION: This study suggests that NEX method is inappropriate for adult patients to estimate the ideal inserting length of nasogastric tube. Physicians should realize these underinsertions with any side-hole above the gastroesophageal junctions may increase the potential risk of complications.

Morphology of the human xiphoid process: dissection and radiography of cadavers and MDCT of patients.

PURPOSE: The purpose of this study was to evaluate the morphology of xiphoid process by dissection and using radiography of cadavers and multidetector computed tomography (MDCT) in patients. METHODS: The xiphoid processes of 41 cadavers were dissected and taken by radiography. Other 902 patients examined by MDCT were revealed by image post-processing used with multiple planar reconstruction, maximum intensity projection and volume rendering. RESULTS: Xiphoid processes displayed pointed shape in 422 cases (44.75 %), oval shape in 387 cases (41.04 %), and forked shape in 134 cases (14.21 %). The sagittal shape of the xiphoid process was observed as ventrally deviated in 217 cases (23.01 %), dorsally deviated in 191 cases (20.25 %), S-shaped (ahead ventral, then dorsal) in 21 cases (2.23 %), and resembling a hook in 14 of ventral deviated patients and in 19 of those dorsal deviated patients. The foramen of xiphoid processes was found in 544 cases (57.69 %). The pattern L (a large foramen with a diameter of more than 5 mm) appeared in 302 cases (55.51 %), pattern S (a small foramen with a diameter of no more than 5 mm) in 155 cases (28.49 %), pattern LS (a mixture of a large and a small foramina) in 37 cases (6.80 %), and pattern SS (two or more small foramina) in 50 cases (9.19 %). CONCLUSION: Human xiphoid process appeared in morphological diversity. The anatomic structure and ossification degree of xiphoid process was well evaluated by MDCT. Our data may be used for diagnosis and surgical treatment of xiphoid process-related diseases.

Anatomic evaluation of the xiphoid process with 64-row multidetector computed tomography.

OBJECTIVE: The aim of this study was to evaluate the interindividual variations of the xiphoid process in a wide adult group using 64-row multidetector computed tomography (MDCT). MATERIALS AND METHODS: Included in the study were 500 consecutive patients who underwent coronary computed tomography angiography. Multiplanar reconstruction (MPR), maximum intensity projection (MIP) images on coronal and sagittal planes, and three-dimensional volume rendering (VR) reconstruction images were obtained and used for the evaluation of the anatomic features of the xiphoid process. RESULTS: The xiphoid process was present in all patients. The xiphoid process was deviated ventrally in 327 patients (65.4%). In 11 of these 327 patients (2.2%), ventral curving at the end of the xiphoid process resembled a hook. The xiphoid process was aligned in the same axis as the sternal corpus in 166 patients (33.2%). The tip of the xiphoid process was curved dorsally like a hook in three patients (0.6%). In four patients (0.8%), the xiphoid process exhibited a reverse S shape. Xiphoidal endings were single in 313 (62.6%) patients, double in 164 (32.8%), or triple in 23 (4.6%). Ossification of the cartilaginous xiphoid process was fully completed in 254 patients (50.8 %). In total, 171 patients (34.2%) had only one xiphoidal foramen and 45 patients (9%) had two or more foramina. Sternoxiphoidal fusion was present in 214 of the patients (42.8%). CONCLUSIONS: Significant interindividual variations were detected in the xiphoid process. Excellent anatomic evaluation capacity of MDCT facilitates the detection of variations of the xiphoid process as well as the whole ribcage.

Where should the normal position of the umbilicus be in the neonate?

INTRODUCTION: The aim of this study was to determine the normal position of the umbilicus so as to offer a guide to improve cosmetic results after the repair of congenital abdominal wall defects. MATERIALS AND METHODS: The position of the umbilical center was determined in 187 neonates with respect to the xiphoid process, the center of the umbilicus and the pubis. The distance between the xiphoid process and the center of the umbilicus (XU), between the pubis and the center of the umbilicus (PU) and from the xiphoid process to the pubis (XP) were measured while the babies lay in a supine position. The PU:XU ratio was calculated based on these measurements. RESULTS: Mean XP was 11.93±1.40 cm, mean XU was 7.41±1.08 cm and mean PU was 4.52±0.70 (mean±SD). The PU:XU ratio was calculated as 0.61±0.12 (ratio±SD). CONCLUSION: We suggest that the PU:XU ratio should be 0.61 offering an ideal localization in umbilical reconstruction.

Estudio de la anatomía quirúrgica del ángulo xifoideo / Study of the surgical anatomy of the xiphoid angle’s

Fundamento: una de las operaciones más laboriosas y complejas son las practicadas en el hiatus esofágico, para el tratamiento de la úlcera péptica y otras enfermedades, dada su localización anatómica y la necesidad de utilizar varios ayudantes en un campo quirúrgico reducido. Objetivo: definir las características anatómicas del ángulo xifoideo que permita diseñar un retractor quirúrgico a utilizar en esta región. Método: se realizó un estudio descriptivo y prospectivo, el universo se constituyó por doscientos dieciocho trabajadores del Hospital Universitario Manuel Ascunce Domenech de Camagüey, se escogió una muestra al azar de cien adultos. Se analizaron las variables biotipo, edad, sexo, peso, talla, medidas del ángulo xifoideo y ancho del apéndice xifoides. Resultados: el promedio de edad fue de 35,5 años; el peso promedio 64,8kg; la talla media fue 1,64m; el ángulo xifoideo 86,8º promedio; el ancho del apéndice xifoideo fue 1,82cm como promedio. Conclusiones: el ancho promedio del apéndice xifoides fue de 1,82cm.

Background: one of the most laborious and complex surgical procedures are those practiced in the hiatus oesophageus, for the treatment of the peptic ulcer and other diseases, given their anatomical localization and the necessity to use several assistants in a reduced surgical field. Objective: to define the anatomical characteristics of xiphoid angle’s that allows designing a surgical retractor to use in this region. Method: a descriptive and prospective study was carried out, the universe was constituted by two-hundred eighteen workers of the University Hospital Manuel Ascunce Domenech of Camagüey, a random sampling of one-hundred adults was chosen. Variables like biotype, age, sex, weight, height, measures of xiphoid angle’s and width of the xiphoid appendix were analyzed. Results: the average age was of 35,5 years; the average weight of 64,8 Kg; the average height was of 1,64m; the average xiphoid angle 86,8º; the width of xiphoid appendix was 1,82cm as average. Conclusions: the width average of xiphoid appendix was 1,82cm.

Variation in surface marking of superior epigastric vessels. A guide to safe laparoscopic port insertion.

This study aimed to map surface markings of the superior epigastric artery, to provide safe landmarks for the placement of trochars in laparoscopic surgery. Seventeen cadavers were dissected and surface anatomy of the superior epigastric artery was defined at two levels: the xiphoid process, and midway between the xiphoid process and umbilicus. Safe sites for insertion of ports were determined in cadavers by dissecting and locating the main trunks of the superior epigastric artery. At the level of the xiphoid process, the distance from the midline ranged from 3.9cm to 4.8cm with a mean of 4.3cm (SD +/- 0.2cm) while midway between the xiphoid process and umbilicus, the distance of the superior epigastric artery from the midline ranged from 4 to 7.5cm, with a mean of 5.7cm (SD +/- 0.7cm). In this area the artery is vulnerable to damage, hence it can be declared as a danger zone.

Predicting internal distance to the stomach for positioning nasogastric and orogastric feeding tubes in children.

AIM: This paper is a report of a study to examine how well direct morphological distances commonly used for nasogastric or orogastric tube insertion and other methods perform as predictors of the internal distance to the targeted position for the tube pores in the stomach. BACKGROUND: Previous studies with very small samples have indicated that commonly used distances give malplacements, either above the oesophagogastric junction or below the body of the stomach, perhaps as much as 33% of the time. METHODS: We compared the predicted distances to the endoscopic and manometric distances to the oesophagogastric junction and to the body of the stomach in a prospective study of 494 children, 2 weeks to 19 years (231 months) of age. Data were collected from 1991 to 1998 and in 2005. RESULTS: The nose-ear-xiphoid distance commonly used in nursing, and other morphological distances, often gave estimates that were either shorter than that to the oesophagogastric junction or longer than that to the distal margin of the body of the stomach. Age-specific methods for predicting the distance to the body of the stomach based on height gave highly accurate predictions of the internal distances. CONCLUSION: Age-specific methods have the potential to predict accurately the distances to the body of the stomach in 98.8% of children from 0.5 to 100 months of age and in 96.5% of children over 100 months of age. Where age-specific prediction methods cannot be used, the next best choice is the nose or mouth to ear-mid-xiphoid-umbilicus span.

Counting ribs on CT by assessing costal attachments to the proximal xiphoid: is this method accurate?

OBJECTIVES: To evaluate the usefulness of the method of counting ribs by assessing anatomic variations of the attachments of costal cartilages to the proximal xiphoid. MATERIALS AND METHODS: From January to September 2005, 224 subjects (136 men, 88 women, age 13 to 89 years, mean age 55 years) underwent computed tomography examination of the chest. Axial images of the chest were obtained on a 16-slice multidetector computed tomography. Counting ribs was performed by using the medial clavicle as an anatomic landmark to identify the first costal cartilage. We analyzed variety and incidence of the attachment patterns of costal cartilages to the proximal xiphoid. RESULT: Out of the 224 patients, the last costal attachments to the proximal xiphoid were the sixth costal cartilages bilaterally for 2 (0.9%) subjects, one 6th and one 7th for 4 (1.8%) subjects, bilateral seventh for 191 (85.3%) subjects, one 7th and one 8th for 15 (6.7%) subjects, and bilateral eighth for 12 (5.4%) subjects. CONCLUSIONS: The method of counting ribs from the proximal xiphoid is inaccurate because the sixth, seventh, and eighth costal cartilages may each attach to the proximal xiphoid.

Technical consideration for subxiphoidal incisional hernia repair.

BACKGROUND: The main principle of incisional hernia repair with mesh augmentation is a wide overlap of at least 5 cm in all directions. This is complicated when cartilaginous or osseous structures border the fascial defect, most notably at the xiphoid after sternotomy or in large proximal incisional hernias. METHOD: We performed an anatomic investigation of this "problematic" area with its different structures and layers that form the retroxiphoidal space. RESULTS AND CONCLUSION: The posterior lamina of the rectus sheath inserts on the posterior side of the xiphoid. This lamina inhibits a sufficient mesh placement. By sharp dissection dorsal the xiphoid process, the posterior lamina of the rectus sheath can be detached. This way the retroxiphoidal space can be opened. Further development of this space can be made by blunt dissection. In some cases, with retroxiphoidal scar formation after sternotomy, a sharp dissection might be necessary. This enables a combined retromuscular-retroxiphoid mesh augmentation repair with a sufficient underlay of at least 5 cm, according to the principles of sublay technique.

Pediatric orogastric and nasogastric tubes: a new formula evaluated.

STUDY OBJECTIVE: We sought to compare the traditional method of determining depth of gastric tube insertion, by measuring from the external landmarks of the nose or mouth, to the earlobe, to the xiphoid process (NEX method), with a graph for determining depth of gastric tube insertion that is based on patient height (graphic method). METHODS: A prospective, randomized, double-blinded study comparing NEX and graphic methods for gastric tube depth of insertion was undertaken. This study included a convenience sample of pediatric emergency department patients in need of gastric intubation. Patients were block randomized, and their gastric tubes were placed to the depth derived from the particular method employed. Alternate depth of insertion was measured on all patients. Abdominal radiographs were used to determine the distance that the end of the tube was from the center of the stomach. RESULTS: Forty-four patients each were in the NEX and graphic groups. The mean distance from the center of the stomach was -1.12 cm (SD 1.36) for the graphic group, compared with 1.31 cm (SD 3.39) for the NEX method. The difference between the 2 methods was 2.43 cm (95% confidence interval [CI] 1.33 to 3.54). Using absolute values, the mean distance from the center of the stomach was 1.26 cm (SD 1.23) for the graphic group compared with 2.60 cm (SD 2.51) for the NEX method. Using these values, the difference between the groups is 1.34 cm (95% CI 0.50 to 2.18). CONCLUSION: When compared with the NEX method, the graphic method demonstrates a significant ability to more consistently and accurately determine the depth of pediatric gastric tube insertion.

El proceso xifoides del esternón mapuche / The xiphoid process of the mapucheïs sternum

El proceso xifoides es la parte más pequeña y variable del esternón. Según los diferentes estudios realizados este puede presentar variadas formas, puede ser ancho y fino, puntiagudo, bífido, perforado, curvado o desviado para un lado y otro. Con el objetivo de determinar las características morfológicas de esta parte del esternón en individuos mapuches estudiamos 50 esternones obtenidos de necropsias de individuos adultos. Los huesos fueron preparados por técnicas tradicionales de maceración de los tejidos blandos. El proceso xifoides se presentó bífido en 42 por ciento de los casos, en forma de paleta en 38 por ciento, ovalados y elipsoides en 10 por ciento y presentó otras formas en 10 por ciento. Sus diámetros máximos en promedio fueron: vertical 38 mm, laterolateral 21,9 mm y anteroposterior 2,3 mm. En relación a su orientación, el proceso xifoides se presentó: sin inclinación en 32 por ciento de los casos, inclinado hacia la izquierda en 24 por ciento, inclinado hacia ventral en 16 por ciento, inclinado hacia derecha en 10 por ciento e inclinado hacia dorsal en 4 por ciento. En el 12 por ciento de los casos presentó forámenes. El en el 58 por ciento de los casos el proceso xifoides se articulaba sólo con la región más posterior de la parte inferior del cuerpo del esternón. Nuestro estudio demuestra la variabilidad morfológica del proceso xifoides confirmando lo observado en otros grupos étnicos

Fine structure of cartilage elastic system fibers, in particular those of the mandibular condyle.

Light microscopy of the mandibular joint tissues from fetal mice show a distribution of fibrillar structures in the articular fibrous capsule covering the condylar head. Further SEM and TEM studies were conducted on autoclaved xiphoid and mandibular condylar processes of the fetuses for observation of the elastic system fibers in these cartilaginous tissues. SEM showed that non-collaginous fibers branched and united to form a complicated network in the cartilage. A fine structure study on diameter distribution of the fibers indicated elastogenesis in the differentiating cell layer and fiber maturation in the articular surfaces and calcification layer, thus suggesting a sequential development, growth, and degeneration of the cellular and fibrillar components in the cartilage, as well as bidirectional cell differentiation in the growing mandibular joint. A further TEM study on these autoclaved connective tissues showed the elastic system fibers in the network to be composed of fine microfibrils and amorphous elastin. The elastic fibers in the condylar cartilage were a loose network having many tortuous main and oblique elastic fibers, and coiling oxytalan fibers.

Structural and metabolic changes characterizing the aging of various cartilages in mice.

It is well documented that various organs and tissues in the body show a differential, non-homogeneous pattern of development and aging. The present study evaluates some of the morphological and metabolic changes characterizing the aging of different types of cartilages in normal male mice. Representatives of hyaline, fibrous, articular and elastic types of cartilage were obtained from animals ranging from 1 week to 1 year of age. Our determinations included the following: total body and organ weights, proteins and DNA concentrations, [3H]leucine and [35S]sulfate uptake. The biochemical assays were accompanied by morphological examinations of corresponding tissue specimens. This investigation clearly indicates that the growth and maturational activities of the various cartilages examined attained their completion at a very early stage of life (1-3 months postnatally). Thereafter, a phase of steady state prevails, followed by a gradual but continuous decline in the various metabolic activities. The morphological findings illustrate the nature of the age-related structural changes. The present findings indicate that a skeletal tissue such as cartilages of various types, tends to age early during the lifespan of the animal.