Gourt > Science > Biology > Developmental Biology > Model Organisms > Mammalian
The mammals are the class of vertebrate animals characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; and endothermic or "warm-blooded" bodies. The brain regulates endothermic and circulatory systems, including a four-chambered heart. Mammals encompass some 5,500 species (including Humans), distributed in about 1,200 genera, 152 families and up to 46 orders, though this varies with the classification scheme.
Phylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals).
Mammal anatomy
Skeletal system
The vast majority of mammals have seven cervical vertebrae (neck bones), including bats, giraffes, whales, and humans. The few exceptions include the manatee and the two-toed sloth, which each have only six cervical vertebrae, and the three-toed sloth with nine cervical vertebrae. More on [ Mammal ]
Developmental Dynamics
Diverse roles of E-cadherin in the morphogenesis of the submandibular gland: Insights into the formation of acinar and ductal structures
Janice L. Walker, A. Sue Menko, Sheede Khalil, Ivan Rebustini, Matthew P. Hoffman, Jordan A. Kreidberg, Maria A. Kukuruzinska Wed, 24 Sep 2008 02:24:00 -0000
The formation of acinar and ductal structures during epithelial tissue branching morphogenesis is not well understood. We report that in the mouse submandibular gland (SMG), acinar and ductal cell fates are determined early in embryonic morphogenesis with E-cadherin playing pivotal roles in development. We identified two morphologically distinct cell populations at the single bud stage, destined for different functions. The outer layer of columnar cells with organized E-cadherin junctions expressed the neonatal acinar marker B1 by E13.5, demonstrating their acinar fate. The interior cells initially lacked distinct E-cadherin junctions, but with morphogenesis formed cytokeratin 7 (K7) -positive ductal structures with organized E-cadherin junctions and F-actin filaments. Inhibition of E-cadherin function with either siRNA or function blocking antibody caused extensive apoptosis of ductal cells and aberrantly dilated lumens, providing the first evidence that E-cadherin regulates ductal lumen formation during branching morphogenesis of the salivary gland. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Multiple evolutionarily conserved enhancers control expression of Eya1
Tadashi Ishihara, Shigeru Sato, Keiko Ikeda, Hiroshi Yajima, Kiyoshi Kawakami Wed, 24 Sep 2008 02:24:00 -0000
Eya1 is a homolog of eyes absent in Drosophila, and essential for various organ formations in vertebrates. Mouse and chick Eya1 shows dynamic expression pattern in early development. We identified ten independent Eya1 enhancers by screening evolutionarily conserved sequences. They exhibited enhancer activities in Hensen's node, neural tube, migrating neural crest cells, otic vesicle, olfactory placode, cranial ganglia, and somites at HH6-17 of chick embryo. The sum of the enhancer activities of the enhancers covers the endogenous expression domains of Eya1 common to chick and mouse. Enhancer activities were also observed in species-specific expression domains such as trigeminal ganglia and brain. Mutational study of one of the enhancers revealed that the enhancer is composed of positive and negative cis-regulatory elements. Thus, we successfully identified a comprehensive group of enhancers around Eya1 locus, which are probably involved in the control of the complex expression pattern of Eya1 in vivo. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Activation of the Wnt/[beta]-catenin signaling reporter in developing mouse olfactory nerve layer marks a specialized subgroup of olfactory ensheathing cells
Ya-Zhou Wang, Andrei Molotkov, Lanying Song, Yunhong Li, David E. Pleasure, Cheng-Ji Zhou Wed, 24 Sep 2008 02:24:00 -0000
Wnt reporter TOPgal mice carry a [beta]-galactosidase ([beta]gal) gene under the control of the Wnt/[beta]-catenin signaling responsive elements. We found that the intensely immunolabeled [beta]gal+ cells were co-immunolabeled with Nestin and formed a tangentially oriented single-cell layer in the "connecting or docking zone" where the olfactory sensory axons attached to the brain surface during mid-gestation. During early postnatal development, [beta]gal+ cells were located in the inner olfactory nerve layer (ONLi) and co-labeled with olfactory ensheathing cell (OEC) markers S100[beta] and NPY but not with lineage-specific markers for neurons, oligodendrocytes, astrocytes, and microglia, demonstrating that the TOPgal marked a subpopulation of OECs. By confocal microscopy, we found that TOPgal activated processes extended along the developing glomerulus and formed multiple tunnel-like structures that ensheathe and bridge olfactory sensory axonal bundles from ONLi to the glomerulus, which may play a key role in glomerulus formation and convergent sorting of the peripheral olfactory axons. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Expression profile and estrogenic regulation of anti-Müllerian hormone during gonadal development in pejerrey Odontesthes bonariensis, a teleost fish with strong temperature-dependent sex determination
Juan Ignacio Fernandino, Ricardo Shohei Hattori, Hiroyuki Kimura, Carlos Augusto Strüssmann, Gustavo Manuel Somoza Wed, 24 Sep 2008 02:25:00 -0000
Pejerrey is a teleost fish presenting a strong temperature-dependent sex determination. This study was conducted to clone pejerrey amh cDNA, analyze its expression profile during thermal and endocrine manipulation of gonadal differentiation, and compare its expression with that of gonadal aromatase (cyp19a1). Amh displayed higher expression at masculinizing than at feminizing temperatures during the gonadal differentiation period. Its expression at an intermediate temperature (females 1:1 males), was high in half of the larvae and low in the other half. Cyp19a1 showed a reciprocal expression pattern to that of amh both individually- and temperature-wise. Increased cyp19a1 and amh expression was observed before morphological gonadal differentiation. Amh expression in larvae feminized by administration of estradiol or masculinized by the administration of an aromatase inhibitor was down- and up-regulated, respectively. These results show that amh plays a critical role in testicular differentiation and it is apparently modulated by estrogens in this species. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Nuclear receptor BgFTZ-F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica
Josefa Cruz, Claudia Nieva, Daniel Mané-Padrós, David Martín, Xavier Bellés Wed, 24 Sep 2008 02:25:00 -0000
Postembryonic development of holometabolous and hemimetabolous insects occurs through successive molts triggered by 20-hydroxyecdysone (20E). The molecular action of 20E has been extensively studied in holometabolous insects, but data on hemimetabolous are scarce. We have demonstrated that during the nymphal development of the hemimetabolous insect Blattella germanica, 20E binds to the heterodimeric receptor formed by the nuclear receptors BgEcR-A and BgRXR activating a cascade of gene expression, including the nuclear receptors BgE75 and BgHR3. Herein, we report the characterization of BgFTZ-F1, another nuclear hormone receptor involved in 20E action. BgFTZ-F1 is activated at the end of each instar, and RNAi has demonstrated that BgHR3 is needed for BgFTZ-F1 activation, and that BgFTZ-F1 has critical functions of during the last nymphal instar. Nymphs with silenced BgFTZ-F1 cannot ecdyse, arrest development, and show structures of ectodermal origin duplicated. BgFTZ-F1 also controls the timing of the ecdysteroid molting pulse. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Expression of the fras1/frem gene family during zebrafish development and fin morphogenesis
Philippe Gautier, Cecilia Naranjo-Golborne, Martin S. Taylor, Ian J. Jackson, Ian Smyth Wed, 24 Sep 2008 02:25:00 -0000
Mouse studies have highlighted the requirement of the extracellular matrix Fras and Frem proteins for embryonic epidermal adhesion. Mutations of the genes encoding some of these proteins underlie the blebs mouse mutants, whereas mutations in human FRAS1 and FREM2 cause Fraser syndrome, a congenital disorder characterized by embryonic blistering and renal defects. We have cloned the zebrafish homologues of these genes and characterized their evolutionary diversification and expression during development. The fish gene complement includes fras1, frem1a, frem1b, frem2a, frem2b, and frem3, which display complex overlapping and complementary expression patterns in developing tissues including the pharyngeal arches, hypochord, musculature, and otic vesicle. Expression during fin development delineates distinct populations of epidermal cells which have previously only been described at a morphological level. We detect relatively little gene expression in epidermis or pronephros, suggesting that the essential role of these proteins in mediating their development in humans and mice is recently evolved. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
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Diverse roles of E-cadherin in the morphogenesis of the submandibular gland: Insights into the formation of acinar and ductal structures
Janice L. Walker, A. Sue Menko, Sheede Khalil, Ivan Rebustini, Matthew P. Hoffman, Jordan A. Kreidberg, Maria A. Kukuruzinska Wed, 24 Sep 2008 02:24:00 -0000
The formation of acinar and ductal structures during epithelial tissue branching morphogenesis is not well understood. We report that in the mouse submandibular gland (SMG), acinar and ductal cell fates are determined early in embryonic morphogenesis with E-cadherin playing pivotal roles in development. We identified two morphologically distinct cell populations at the single bud stage, destined for different functions. The outer layer of columnar cells with organized E-cadherin junctions expressed the neonatal acinar marker B1 by E13.5, demonstrating their acinar fate. The interior cells initially lacked distinct E-cadherin junctions, but with morphogenesis formed cytokeratin 7 (K7) -positive ductal structures with organized E-cadherin junctions and F-actin filaments. Inhibition of E-cadherin function with either siRNA or function blocking antibody caused extensive apoptosis of ductal cells and aberrantly dilated lumens, providing the first evidence that E-cadherin regulates ductal lumen formation during branching morphogenesis of the salivary gland. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Multiple evolutionarily conserved enhancers control expression of Eya1
Tadashi Ishihara, Shigeru Sato, Keiko Ikeda, Hiroshi Yajima, Kiyoshi Kawakami Wed, 24 Sep 2008 02:24:00 -0000
Eya1 is a homolog of eyes absent in Drosophila, and essential for various organ formations in vertebrates. Mouse and chick Eya1 shows dynamic expression pattern in early development. We identified ten independent Eya1 enhancers by screening evolutionarily conserved sequences. They exhibited enhancer activities in Hensen's node, neural tube, migrating neural crest cells, otic vesicle, olfactory placode, cranial ganglia, and somites at HH6-17 of chick embryo. The sum of the enhancer activities of the enhancers covers the endogenous expression domains of Eya1 common to chick and mouse. Enhancer activities were also observed in species-specific expression domains such as trigeminal ganglia and brain. Mutational study of one of the enhancers revealed that the enhancer is composed of positive and negative cis-regulatory elements. Thus, we successfully identified a comprehensive group of enhancers around Eya1 locus, which are probably involved in the control of the complex expression pattern of Eya1 in vivo. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Activation of the Wnt/[beta]-catenin signaling reporter in developing mouse olfactory nerve layer marks a specialized subgroup of olfactory ensheathing cells
Ya-Zhou Wang, Andrei Molotkov, Lanying Song, Yunhong Li, David E. Pleasure, Cheng-Ji Zhou Wed, 24 Sep 2008 02:24:00 -0000
Wnt reporter TOPgal mice carry a [beta]-galactosidase ([beta]gal) gene under the control of the Wnt/[beta]-catenin signaling responsive elements. We found that the intensely immunolabeled [beta]gal+ cells were co-immunolabeled with Nestin and formed a tangentially oriented single-cell layer in the "connecting or docking zone" where the olfactory sensory axons attached to the brain surface during mid-gestation. During early postnatal development, [beta]gal+ cells were located in the inner olfactory nerve layer (ONLi) and co-labeled with olfactory ensheathing cell (OEC) markers S100[beta] and NPY but not with lineage-specific markers for neurons, oligodendrocytes, astrocytes, and microglia, demonstrating that the TOPgal marked a subpopulation of OECs. By confocal microscopy, we found that TOPgal activated processes extended along the developing glomerulus and formed multiple tunnel-like structures that ensheathe and bridge olfactory sensory axonal bundles from ONLi to the glomerulus, which may play a key role in glomerulus formation and convergent sorting of the peripheral olfactory axons. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Expression profile and estrogenic regulation of anti-Müllerian hormone during gonadal development in pejerrey Odontesthes bonariensis, a teleost fish with strong temperature-dependent sex determination
Juan Ignacio Fernandino, Ricardo Shohei Hattori, Hiroyuki Kimura, Carlos Augusto Strüssmann, Gustavo Manuel Somoza Wed, 24 Sep 2008 02:25:00 -0000
Pejerrey is a teleost fish presenting a strong temperature-dependent sex determination. This study was conducted to clone pejerrey amh cDNA, analyze its expression profile during thermal and endocrine manipulation of gonadal differentiation, and compare its expression with that of gonadal aromatase (cyp19a1). Amh displayed higher expression at masculinizing than at feminizing temperatures during the gonadal differentiation period. Its expression at an intermediate temperature (females 1:1 males), was high in half of the larvae and low in the other half. Cyp19a1 showed a reciprocal expression pattern to that of amh both individually- and temperature-wise. Increased cyp19a1 and amh expression was observed before morphological gonadal differentiation. Amh expression in larvae feminized by administration of estradiol or masculinized by the administration of an aromatase inhibitor was down- and up-regulated, respectively. These results show that amh plays a critical role in testicular differentiation and it is apparently modulated by estrogens in this species. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Nuclear receptor BgFTZ-F1 regulates molting and the timing of ecdysteroid production during nymphal development in the hemimetabolous insect Blattella germanica
Josefa Cruz, Claudia Nieva, Daniel Mané-Padrós, David Martín, Xavier Bellés Wed, 24 Sep 2008 02:25:00 -0000
Postembryonic development of holometabolous and hemimetabolous insects occurs through successive molts triggered by 20-hydroxyecdysone (20E). The molecular action of 20E has been extensively studied in holometabolous insects, but data on hemimetabolous are scarce. We have demonstrated that during the nymphal development of the hemimetabolous insect Blattella germanica, 20E binds to the heterodimeric receptor formed by the nuclear receptors BgEcR-A and BgRXR activating a cascade of gene expression, including the nuclear receptors BgE75 and BgHR3. Herein, we report the characterization of BgFTZ-F1, another nuclear hormone receptor involved in 20E action. BgFTZ-F1 is activated at the end of each instar, and RNAi has demonstrated that BgHR3 is needed for BgFTZ-F1 activation, and that BgFTZ-F1 has critical functions of during the last nymphal instar. Nymphs with silenced BgFTZ-F1 cannot ecdyse, arrest development, and show structures of ectodermal origin duplicated. BgFTZ-F1 also controls the timing of the ecdysteroid molting pulse. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Expression of the fras1/frem gene family during zebrafish development and fin morphogenesis
Philippe Gautier, Cecilia Naranjo-Golborne, Martin S. Taylor, Ian J. Jackson, Ian Smyth Wed, 24 Sep 2008 02:25:00 -0000
Mouse studies have highlighted the requirement of the extracellular matrix Fras and Frem proteins for embryonic epidermal adhesion. Mutations of the genes encoding some of these proteins underlie the blebs mouse mutants, whereas mutations in human FRAS1 and FREM2 cause Fraser syndrome, a congenital disorder characterized by embryonic blistering and renal defects. We have cloned the zebrafish homologues of these genes and characterized their evolutionary diversification and expression during development. The fish gene complement includes fras1, frem1a, frem1b, frem2a, frem2b, and frem3, which display complex overlapping and complementary expression patterns in developing tissues including the pharyngeal arches, hypochord, musculature, and otic vesicle. Expression during fin development delineates distinct populations of epidermal cells which have previously only been described at a morphological level. We detect relatively little gene expression in epidermis or pronephros, suggesting that the essential role of these proteins in mediating their development in humans and mice is recently evolved. Developmental Dynamics, 2008. © 2008 Wiley-Liss, Inc.
Comparative Placentation - Provides an examination and evaluation of placenta from many different types of mammals. Includes glossary, taxonomy and biography of author, maintained by the University of California, San Diego.
Meta Description: [ kurt benirschke, comparative placentation, placenta ]
Edinburgh Mouse Atlas Project - Computer modeling of stages of mouse embryogenesis to map the expression of different genes. 3D Embryo Anatomy Atlas and gene expression database at MRC Human Genetics Unit, Edinburgh.
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