Prior work identified a novel association between bone robustness and porosity, which may be part of a broader interaction whereby the skeletal system compensates for the natural variation in robustness (bone width relative to length) by modulating tissue-level mechanical properties to increase stiffness of slender bones and to reduce mass of robust bones. To further understand this association, we tested the hypothesis that the relationship between robustness and porosity is mediated through intracortical, BMU-based (basic multicellular unit) remodeling. We quantified cortical porosity, mineralization, and histomorphometry at two sites (38 and 66% of the length) in human cadaveric tibiae. We found significant correlations between robustness and several histomorphometric variables (e.g., % secondary tissue [R2 = 0.68, p < 0.004], total osteon area [R2=0.42, p<0.04]) at the 66% site. Although these associations were weaker at the 38% site, significant correlations between histological variables were identified between the two sites indicating that both respond to the same global effects and demonstrate a similar character at the whole bone level. Thus, robust bones tended to have larger and more numerous osteons with less infilling, resulting in bigger pores and more secondary bone area. These results suggest that local regulation of BMU-based remodeling may be further modulated by a global signal associated with robustness, such that remodeling is suppressed in slender bones but not in robust bones. Elucidating this mechanism further is crucial for better understanding the complex adaptive nature of the skeleton, and how inter-individual variation in remodeling differentially impacts skeletal aging and an individuals’ potential response to prophylactic treatments.
The dorsal cochlear nucleus (DCN) is a brainstem structure that receives input from the auditory nerve. Many studies in a diversity of species have shown that the DCN has a laminar organization and identifiable neuron types with predictable synaptic relations to each other. In contrast, studies on the human DCN have found a less distinct laminar organization and fewer cell types, although there has been disagreement among studies in how to characterize laminar organization and which of the cell types identified in other animals are also present in humans. We have reexamined DCN organization in the human using immunohistochemistry to analyze the expression of several proteins that have been useful in delineating the neurochemical organization of other brainstem structures in humans: nonphosphorylated neurofilament protein (NPNFP), nitric oxide synthase (nNOS), and three calcium-binding proteins. The results for humans suggest a laminar organization with only two layers, and the presence of large projection neurons that are enriched in NPNFP. We did not observe evidence in humans of the inhibitory interneurons that have been described in the cat and rodent DCN. To compare humans and other animals directly we used immunohistochemistry to examine the DCN in the macaque monkey, the cat, and three rodents. We found similarities between macaque monkey and human in the expression of NPNFP and nNOS, and unexpected differences among species in the patterns of expression of the calcium-binding proteins.
The cardiac sarcomere is the functional unit for myocyte contraction. Ordered arrays of sarcomeric proteins held in stoichiometric balance with each other, respond to calcium to coordinate contraction and relaxation of the heart. Altered sarcomeric structure-function underlies the primary basis of disease in multiple acquired and inherited heart disease states. Hypertrophic and restrictive cardiomyopathies are caused by inherited mutations in sarcomeric genes and result in altered contractility. Ischemia mediated acidosis directly alters sarcomere function resulting in decreased contractility. In this review, we highlight the use of acute genetic engineering of adult cardiac myocytes through stoichiometric replacement of sarcomeric proteins in these disease states with particular focus on cardiac troponin I. Stoichiometric replacement of disease causing mutations has been instrumental in defining the molecular mechanisms of hypertrophic and restrictive cardiomyopathy in a cellular context. In addition, taking advantage of stoichiometric replacement through gene therapy is discussed, highlighting the ischemia-resistant histidine-button, A164H cTnI. Stoichiometric replacement of sarcomeric proteins offers a potential gene therapy avenue to replace mutant proteins, alter sarcomeric responses to pathophysiologic insults or neutralize altered sarcomeric function in disease.
acute genetic engineering; myofilament; troponin; calcium sensitivity; sarcomere; molecular dynamics; adult cardiac myocytes
Chaperone proteins are critical for protein folding and stability, and hence are
necessary for normal cellular organization and function. Recent studies have begun to
interrogate the role of this specialized class of proteins in muscle biology. During
development, chaperone-mediated folding of client proteins enables their integration into
nascent sarcomeres. In addition to assisting with muscle differentiation, chaperones play
a key role in maintenance of muscle tissues. Further, disruption of the chaperone network
can result in neuromuscular disease. In this review, we discuss how chaperones are
involved in myofibrillogenesis, sarcomere maintenance and muscle disorders. We also
consider the possibilities of therapeutically targeting chaperones to treat muscle
Chaperones; sarcomere; myofibril; protein folding; contractile proteins
Posttranslational addition of Arg to proteins, mediated by arginyltransferase ATE1 has been first observed in 1963 and remained poorly understood for decades since its original discovery. Recent work demonstrated the global nature of arginylation and its essential role in multiple physiological pathways during embryogenesis and adulthood and identified over a hundred of proteins arginylated in vivo. Among these proteins, the prominent role belongs to the actin cytoskeleton and the muscle, and follow up studies strongly suggests that arginylation constitutes a novel biological regulator of contractility. This review presents an overview of the studies of protein arginylation that led to the discovery of its major role in the muscle.
Muscle ankyrin-repeat proteins (MARPs) have been shown to serve diverse functions within cardiac and skeletal muscle cells. Apart from their interactions with sarcomeric proteins like titin or myopalladin that locate them along myofilaments, MARPs are able to shuttle to the nucleus where they act as modulators for a variety of transcription factors. The deregulation of MARPs in many cardiac and skeletal myopathies contributes to their use as biomarkers for these diseases.
Many of their functions are attributed to their domain composition. MARPs consist of an N-terminal coiled-coil domain responsible for their dimerization. The C-terminus contains a series of ankyrin-repeats, whose best-characterized function is to bind to the N2A-region of the giant sarcomeric protein titin.
Here we investigate the nature of their dimerization and their interaction with titin more closely. We demonstrate that the coiled-coil domain in all MARPs enables their homo- and hetero-dimerization in antiparallel fashion. Protein complementation experiments indicate further antiparallel binding of the ankyrin-repeats to titin’s N2A-region. Binding of MARP to titin also affects its PKA mediated phosphorylation. We demonstrate further that MARPs themselves are phosphorylated by PKA and PKC, potentially altering their structure or function. These studies elucidate structural relationships within the stretch-responsive MARP/titin complex in cross-striated muscle cells, and may relate to disease relevant posttranslational modifications of MARPs and titin that alter muscle compliance.
muscle; MARP; titin; phosphorylation; kinase
Several missense mutations in the Z-band protein, myotilin, have been implicated in human muscle diseases such as myofibrillar myopathy, spheroid body myopathy, and distal myopathy. Recently, we have reported the cloning of chicken myotilin cDNA. In this study, we have investigated the expression of myotilin in cross-striated muscles from developing chicken by qRT-PCR and in situ hybridizations. In situ hybridization of embryonic stages shows myotilin gene expression in heart, somites, neural tissue, eyes and otocysts. RT-PCR and qRT-PCR data, together with in situ hybridization results point to a biphasic transcriptional pattern for MYOT gene during early heart development with maximum expression level in the adult. In skeletal muscle, the expression level starts decreasing after embryonic day 20 and declines in the adult skeletal muscles. Western blot assays of myotilin in adult skeletal muscle reveal a decrease in myotilin protein compared with levels in embryonic skeletal muscle. Our results suggest that MYOT gene may undergo transcriptional activation and repression that varies between tissues in developing chicken. We believe this is the first report of the developmental regulation on myotilin expression in non-mammalian species.
chick embryos; myotilin; Z-bands; skeletal muscle; heart
The dystrophin-associated glycoprotein complex (DGC) is a collection of glycoproteins that are essential for the normal function of striated muscle and many other tissues. Recent genetic studies have implicated the components of this complex in over a dozen forms of muscular dystrophy. Furthermore, disruption of the DGC has been implicated in many forms of acquired disease. This review aims to summarize the current state of knowledge regarding the processing and assembly of dystrophin associated proteins with a focus primarily on the dystroglycan heterodimer and the sarcoglycan complex. These proteins form the transmembrane portion of the DGC and undergo a complex multi-step processing with proteolytic cleavage, differential assembly, and both N- and O-glycosylation. The enzymes responsible for this processing and a model describing the sequence and subcellular localization of these events are discussed.
It is important to understand how muscle forms normally in order to understand muscle diseases that result in abnormal muscle formation. Although the structure of myofibrils is well understood, the process through which the myofibril components form organized contractile units is not clear. Based on the staining of muscle proteins in avian embryonic cardiomyocytes, we previously proposed that myofibrils formation occurred in steps that began with premyofibrils followed by nascent myofibrils and ending with mature myofibrils. The purpose of this study was to determine whether the premyofibril model of myofibrillogenesis developed from studies developed from studies in avian cardiomyocytes was supported by our current studies of myofibril assembly in mouse skeletal muscle. Emphasis was on establishing how the key sarcomeric proteins, F-actin, non-muscle myosin II, muscle myosin II, and α-actinin were organized in the three stages of myofibril assembly. The results also test previous reports that non-muscle myosins II A and B are components of the Z-Bands of mature myofibrils, data that are inconsistent with the premyofibril model. We have also determined that in mouse muscle cells, telethonin is a late assembling protein that is present only in the Z-Bands of mature myofibrils. This result of using specific telethonin antibodies supports the approach of using YFP-tagged proteins to determine where and when these YFP-sarcomeric fusion proteins are localized. The data presented in this study on cultures of primary mouse skeletal myocytes are consistent with the premyofibril model of myofibrillogenesis previously proposed for both avian cardiac and skeletal muscle cells.
Premyofibrils; Myofibrillogenesis; Non-muscle Myosin II; α-actinin; telethonin
Mutations in sarcomere genes have been found in many inheritable human diseases, including hypertrophic cardiomyopathy. Elucidating the molecular mechanisms of sarcomere assembly shall facilitate understanding of the pathogenesis of sarcomere-based cardiac disease. Recently, biochemical and genomic studies have identified many new genes encoding proteins that localize to the sarcomere. However, their precise functions in sarcomere assembly and sarcomere-based cardiac disease are unknown. Here, we review zebrafish as an emerging vertebrate model for these studies. We summarize the techniques offered by this animal model to manipulate genes of interest, annotate gene expression, and describe the resulting phenotypes. We survey the sarcomere genes that have been investigated in zebrafish and discuss the potential of applying this in vivo model for larger-scale genetic studies.
cardiomyopathy; genetics; myofibrillogenesis; sarcomere; zebrafish
The nematode Caenorhabditis elegans has been used as a valuable system to study structure and function of striated muscle. The body wall muscle of C. elegans is obliquely striated muscle with highly organized sarcomeric assembly of actin, myosin, and other accessary proteins. Genetic and molecular biological studies in C. elegans have identified a number of genes encoding structural and regulatory components for the muscle contractile apparatuses, and many of them have counterparts in mammalian cardiac and skeletal muscles or striated muscles in other invertebrates. Applicability of genetics, cell biology, and biochemistry has made C. elegans an excellent system to study mechanisms of muscle contractility and assembly and maintenance of myofibrils. This review focuses on the regulatory mechanisms of structure and function of actin filaments in the C. elegans body wall muscle. Sarcomeric actin filaments in C. elegans muscle are associated with the troponin-tropomyosin system that regulates the actin-myosin interaction. Proteins that bind to the side and ends of actin filaments support ordered assembly of thin filaments. Furthermore, regulators of actin dynamics play important roles in initial assembly, growth, and maintenance of sarcomeres. The knowledge acquired in C. elegans can serve as bases to understand the basic mechanisms of muscle structure and function.
Smooth muscle (SM) tissue is a complex organization of multiple cell types and is regulated by numerous signaling molecules (neurotransmitters, hormones, cytokines, etc.). SM contractile function can be regulated via expression and distribution of the contractile and cytoskeletal proteins, and activation of any of the second messenger pathways that regulate them. Spatial-temporal changes in the contractile, cytoskeletal or regulatory components of SM cells (SMCs) have been proposed to alter SM contractile activity. Ca2+ sensitization/desensitization can occur as a result of changes at any of these levels, and specific pathways have been identified at all of these levels. Understanding when and how proteins can translocate within the cytoplasm, or toand-from the plasmalemma and the cytoplasm to alter contractile activity is critical. Numerous studies have reported translocation of proteins associated with the adherens junction and G protein-coupled receptor activation pathways in isolated SMC systems. Specific examples of translocation of vinculin to and from the adherens junction and protein kinase C (PKC) and 17 kDa PKC-potentiated inhibitor of myosin light chain phosphatase (CPI-17) to and from the plasmalemma in isolated SMC systems but not in intact SM tissues are discussed. Using both isolated SMC systems and SM tissues in parallel to pursue these studies will advance our understanding of both the role and mechanism of these pathways as well as their possible significance for Ca2+ sensitization in intact SM tissues and organ systems.
Establishment of a functional immune system has important implications for health and disease, yet questions remain regarding the mechanism, location, and timing of development of myeloid and lymphoid cell compartments. The goal of this study was to characterize the ontogeny of the myeloid-lymphoid system in rhesus monkeys to enhance current knowledge of the developmental sequence of B cell (CD20, CD79), T cell (CD3, CD4, CD8, FoxP3), dendritic cell (CD205), and macrophage (CD68) lineages in the fetus and infant. Immunohistochemical assessments addressed the temporal and spatial expression of select phenotypic markers in the developing liver, thymus, spleen, lymph nodes, gut-associated lymphoid tissue (GALT), and bone marrow with antibodies known to cross-react with rhesus cells. CD3 was the earliest lymphoid marker identified in the first trimester thymus and, to a lesser extent, in the spleen. T cell markers were also expressed mid-gestation on cells of the liver, spleen, thymus, and in Peyer’s patches of the small and large intestine, and where CCR5 expression was noted. A myeloid marker, CD68, was found on hepatic cells near blood islands in the late first trimester. B cell markers were observed mid-second trimester in the liver, spleen, thymus, lymph nodes, bone marrow spaces, and occasionally in GALT. By the late third trimester and postnatally, secondary follicles with germinal centers were present in the thymus, spleen, and lymph nodes. These results suggest that immune ontogeny in monkeys is similar in temporal and anatomical sequence when compared to humans, providing important insights for translational studies.
Fetus; Infant; Monkey; Immune System; Ontogeny
Facial expression is a universal means of visual communication in humans and many other primates. Humans have the most complex facial display repertoire among primates but gross morphological studies have not found greater complexity in human mimetic musculature. The present study examines microanatomical aspects of mimetic musculature in order to test hypotheses related to human mimetic musculature physiology, function, and evolutionary morphology. Samples from the orbicularis oris (OOM) and the zygomaticus major muscles (ZM) in laboratory mice (N=3), rhesus macaques (N=3) and humans (N=3) were collected. Fiber type proportions (slow-twitch and fast-twitch), fiber cross-sectional area, diameter, and length were calculated and means were statistically compared among groups. Results showed that macaques had the greatest percentage of fast fibers in both muscles (followed by humans) and humans had the greatest percentage of slow fibers in both muscles. Macaques and humans typically did not differ from one another in morphometrics except for fiber length where humans had longer fibers. While sample sizes are low, results from the present study may indicate that the rhesus macaque OOM and ZM are specialized primarily to assist with maintenance of the rigid dominance hierarchy via rapid facial displays of submission and aggression while human musculature may have evolved not only under pressure to work in facial expressions but also in development of speech.
facial muscle; orbicularis oris; zygomaticus major; speech; fiber type
There is considerable individual variation in the timing, duration, and intensity of growth that occurs in the craniofacial complex during childhood and adolescence. The purpose of this paper is to describe the extent of this variation between traits and between individuals within the Fels Longitudinal Study. Polynomial multilevel models were used to estimate the ages of onset, peak velocity, and cessation of adolescent growth, the time between these ages, the amount of growth between these ages, and peak velocity. This was done at both the group and individual levels for standard cephalometric measurements of the lengths of the mandible, maxilla, and cranial base, the gonial angle, and the saddle angle. Data are from 293 untreated boys and girls age 4 to 24 years in the Fels Longitudinal Study. The timing of the adolescent growth spurt was, in general, not significantly different between the mandible and the maxilla, with each having an earlier age of onset, later age of peak velocity, and later age of cessation of growth compared to the cranial base length. Compared to lengths, angles had in general later ages of onset, peak velocity, and cessation of growth. Accurate characterization of the ontogenetic trajectories of the traits in the craniofacial complex is critical for both clinicians seeking to optimize treatment timing and anatomists interested in examining heterochrony.
craniofacial; puberty; development; mathematical modeling; maturation; multilevel model; orthodontics
This study focuses on the gross anatomy, anatomic relations, microanatomy, and meaning of three enigmatic, geographically-patterned, quasi-continuous superstructures of the posterior cranium. Collectively known as occipital superstructures (OSS), these traits are the occipital torus tubercle (TOT), retromastoid process (PR), and posterior supramastoid tubercle (TSP). When present, TOT, PR and TSP develop at posterior cranial attachment sites of the upper trapezius, superior oblique and sternocleidomastoid muscles, respectively. Marked expression and co-occurrence of these OSS are virtually circumscribed within Oceania and reach highest recorded frequencies in proto-historic Chamorros (CHamoru) of the Mariana Islands. Prior to undertaking scanning electron microscopy (SEM) work, our working multifactorial model for OSS development was that early-onset, long-term, chronic activity-related microtrauma at enthesis sites led to exuberant reactive or reparative responses in a substantial minority of genetically predisposed (and mostly male) individuals. SEM imaging, however, reveals topographic patterning that questions, but does not negate, activity-induction of these superstructures. While OSS appear macroscopically as relatively large and discrete phenomena, SEM findings reveal a unique, widespread and seemingly systemic distribution of structures over the occipital surface that have the appearance of OSS microforms. Nevertheless, apparent genetic underpinnings, anatomic relationships with muscle entheses, and positive correlation of OSS development with humeral robusticity continue to suggest that these superstructures have potential to at once bear witness to Chamorro population history and inform osteobiographical constructions of chronic activity patterns in individuals bearing them. Further work is outlined that would illuminate the proximate and ultimate meanings of OSS.
Chamorros; occipital torus tubercle; retromastoid process; posterior supramastoid tubercle; entheses; functional anatomy; SEM survey
This study provides a histological comparison of the mature regenerated and original tail of the lizard Anolis carolinensis. These data will provide a framework for future studies of this emerging model organism whose genome was recently published. This study demonstrated that the cartilage skeleton of the regenerated tail enclosed a spinal cord with an ependymal core, but there was no evidence that dorsal root ganglia or peripheral nerves are regenerated. The cartilage tube contained foramina that allowed the vasculature to cross, but was otherwise a rigid structure. The original tail has muscle groups arranged in quadrants in a regular pattern that attach to the vertebral column. The regenerated tail has irregular muscle bundles of variable number that form unusual attachments to each other and to the cartilage tube. Furthermore, the data show that there was increased connective tissue within the muscle bundles. Implications for functionality of the regenerated tail and for future biomechanical studies are discussed.
Idiopathic chronic diarrhea (ICD) is a common cause of morbidity and mortality among juvenile rhesus macaques. While lesions may be absent at colonoscopy, the histopathologic evaluation of the biopsy specimens is consistent with human macroscopic colitis (MC). In this study, we developed an isotropic uniform random sampling method to evaluate macroscopic and microscopic changes and applied it on proximal ascending colon in monkeys. Colonic tissue and peripheral blood specimens were collected from six MC and six control juvenile macaques at necropsy. Uniform random samples were collected from the colon using punch biopsy tools. The volume of epithelium and lamina propria were estimated in thick (25 µm) sections using point probes and normalized to the area of muscularis mucosae. Our data suggests a significant increase of the Vs of the lamina propria (1.9 fold, p=0.02) and epithelium (1.4 fold, p=0.05) in subjects with MC. The average colonic surface mucosa area in the MC monkeys increased 1.4 fold over the controls (p=0.02). The volume of the proximal colon in animals with MC showed a 2.4 fold increase over the non-diarrhea control monkeys (p=0.0001). Cytokine, chemokine, and growth factor levels in peripheral blood were found to be correlated with the volume estimate of the lamina propria and epithelium. We found that ICD in macaques has features which simulates human MC and can be used as a spontaneous animal model for human MC. Furthermore, this developed sampling method can be used for unbiased evaluation of therapeutics in clinical trials of this animal model.
Our previous work has shown that stone formers who form calcium phosphate (CaP) stones that contain any brushite (BRSF) have a distinctive renal histopathology and surgical anatomy when compared to idiopathic calcium oxalate stone formers (ICSF). Here we report on another group of idiopathic CaP stone formers, those forming stone containing primarily hydroxyapatite, in order to clarify in what ways their pathology differs from BRSF and ICSF. Eleven hydroxyapatite stone formers (HASF) (2 males, 9 females) were studied using intra-operative digital photography and biopsy of papillary and cortical regions to measure tissue changes associated with stone formation. Our main finding is that HASF and BRSF differ significantly from each other and that both differ greatly from ICSF. Both BRSF and ICSF patients have significant levels of Randall’s plaque compared to HASF. Intra-tubular deposit number is greater in HASF than BRSF and non-existent in ICSF while deposit size is smaller in HASF than BRSF. Cortical pathology is distinctly greater in BRSF than HASF. Four attached stones were observed in HASF, three in 25 BRSF and 5–10 per ICSF patient. HASF and BRSF differ clinically in that both have higher average urine pH, supersaturation of CaP, and calcium excretion than ICSF. Our work suggests that HASF and BRSF are two distinct and separate diseases and both differ greatly from ICSF.
For more than a century there has been debate concerning the mechanism of accommodation—whether the lens capsule or lens material itself determines the functional relationship between ciliary muscle contractility and lens deformation during refractive adaptation. This morphological study in monkey eyes investigates the composition and distribution of several connective tissue components in the accommodative apparatus relaying muscle force to lens organization. Elastin distributes on the marginal surface of the ciliary process. A zonule is composed of fibrillin produced by epithelial cells of the process. In the progress of extension over the posterior chamber, fibrils unite into strands and possess longitudinal plasticity. By induction of the elastin network, strands extend in a concentric direction covering the equatorial region of the capsule. Upon tethering to the lens, the strand ramifies into fibrils, penetrating deeply close to the epithelial layer of the lens and binding with the collagen of the intercellular spaces. Tight linkage of the zonule with the capsule transmits precise contractility. Inside the lens, the cortical layer's elastic connective tissue network forms widely spaced lamellae of crystalline fibers. In contrast, the central nuclear lamellae are tightly opposed. The accumulation of lamellae is greater in the anterior cortex than in the posterior, yielding a more variable anterior chamber depth in the visual axis. The plasticity of the zonule and connective tissue distribution inside the lens produces an adjustable configuration. Thus, tight linkage between the dynamism of the capsule with interaction of the lenticular flexibility provides a novel understanding of accommodation. Anat Rec, 298:630–636, 2015.
accommodation; zonule; fibrillin; elastin; fibronectin; collagen
Microtubule‐associated protein light chain 3 (LC3A) is a reliable marker of autophagy that displays three distinct patterns of immunohistochemical staining in solid tumors: diffuse cytoplasmic staining, juxtanuclear staining, and staining of “stone‐like” structures. These three patterns have a different prognostic significance in many solid tumors, but little is known about their influence in gastric cancer (GC). This study was a retrospective analysis of 188 GC patients from stages I to IV. The pattern of LC3A expression was examined in tumor and nontumor tissues by immunohistochemistry. Then, the association between the pattern of LC3A expression in GC and the prognosis was investigated by Kaplan‐Meier analysis and the Cox proportional hazards model. Two distinct patterns of LC3A immunostaining (diffuse cytoplasmic expression and “stone‐like” structures) were observed in GC tissues. LC3A‐positive “stone‐like” structures were found only in the tumors, and the number of such structures was correlated with both the tumor type and tumor stage. In addition, a high number of LC3A‐positive “stone‐like” structures was closely associated with an increased risk of recurrence after radical resection of stages I–III cancer (P < 0.001; HR = 0.205) and was associated with a lower overall survival rate for stage IV cancer (P < 0.001; HR = 0.364). Taken together, our data demonstrate that LC3A‐positive “stone‐like” structures can be used as an independent biomarker for an adverse prognosis of GC, suggesting that “stone‐like” structures are correlated with the malignancy of this disease. Anat Rec, 297:653–662, 2014. © 2014 The Authors The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology Published by Wiley Periodicals, Inc.
gastric cancer; autophagy; LC3A; stone‐like structure; prognosis
An essential step in the translation of cell-based therapies for kidney repair involves preclinical studies in relevant animal models. Regenerative therapies in children with congenital kidney disease may provide benefit, but limited quantitative data on normal development is available to aid in identifying efficient protocols for repair. Nonhuman primates share many developmental similarities with humans and provide an important translational model for understanding nephrogenesis and morphological changes across gestation. These studies assessed monkey kidney size and weight during development and utilized stereological methods to quantitate total number of glomeruli. Immunohistochemical methods were included to identify patterns of expression of tubular proteins including Aquaporin-1 (AQP1), AQP2, Calbindin, E-Cadherin, and Uromodulin. Results have shown that glomerular number increased linearly with kidney weight, from 1.1 × 103 in the late first trimester to 3.5 × 105 near term (P < 0.001). The ratio of glomeruli to body weight tripled from the late first to early second trimester then remained relatively unchanged. Only AQP1 was expressed in the proximal tubule and descending Loop of Henle. The ascending Loop of Henle was positive for AQP2, Calbindin, and Uromodulin; distal convoluted tubules stained for Calbindin only; and collecting tubules expressed AQP2 and E-Cadherin with occasional Calbindin-positive cells. These findings provide quantitative information on normal kidney ontogeny in rhesus monkeys and further support the importance of this model for human kidney development.
kidney; nephrogenesis; monkey; stereology; fetus