Histogenesis of the Os Penis and Os Clitoridis in Rats

The development of the os penis in normal male rats and the os clitoridis in the females treated with testosterone were studied histologically and histochemically. Alcian blue-positive materials, alkaline phosphatase activities and calcium deposit were detected. The os penis of the rats was composed of a proximal segment and a distal one. The proximal segment of the os penis was formed by the fusion of a membrane bone in its distal half and an ossifying hyaline cartilage in its proximal half. The distal segment of the os penis developed as a fibrocartilage bone.
Two steps were demonstrated in the development of the os penis: the formation of the rudiments, and the differentiation of the proximal and distal segments. The treatment of newborn females with testosterone induced an os clitoridis homologous to the proximal segment of the os penis. The development of the os clitoridis was compared with that of the os penis.     

Os penis of the rat. IV. The proximal growth cartilage

Histomorphological and histochemical aspects of the proximal cartilage of os penis and its surrounding perichondrium in 60 rats aged between 1 and 100 days are described. Comparisons at 11-14 days with the mandibular condylar cartilage reveal a slight difference in their general morphological composition. The developmental changes which take place in the os penis cartilage reveal histomorphologic events, some of which may be brought into agreement with previous observations of patterns of transformations of the bone. Observations on an age-dependent morphological appearance of the area adjacent to the proximal surface of the cartilage suggest certain agreements between the mandibular angular cartilage and the os penis cartilage. The study of phosphomonoesterases in the os penis cartilage and its perichondrium reveals significant, unexplained differences in the distribution of alkaline phosphatase between this cartilage and the mandibular condylar cartilage.     

Tissue Differentiation in Mouse Teratocarcinomas in Lung Colonies from Ascitic Embryoid Bodies

Tissue differentiation in ascitic teratocarcinoma embryoid bodies (EBs) was investigated in the lung colony system of syngeneic 129/Sv and allogeneic Balb/c mice previously reported by us. In this report, tissues are classified as neural, epithelial and mesodermal tissues. Although multiple differentiation in these three groups of tissues became evident about a month following an injection of EBs, colonies containing only one type of tissue but not mesodermal were commonly found. There were few colonies containing only mesodermal or both neural and mesodermal tissues. This suggests that mesodermal tissue differentiation takes place, as in normal embryogenesis, through the formation of a mesodermal layer, which has not been found in vivo.     

The role of growth factors in the embryogenesis and differentiation of the eye.

The vertebrate eye is composed of a variety of tissues that, embryonically, have their derivation from surface ectoderm, neural ectoderm, neural crest, and mesodermal mesenchyme. During development, these different types of cells are subjected to complex processes of induction and suppressive interactions that bring about their final differentiation and arrangement in the fully formed eye. With the changing concept of ocular development, we present a new perspective on the control of morphogenesis at the cellular and molecular levels by growth factors that include fibroblast growth factors, epidermal growth factor, nerve growth factor, platelet-derived growth factor, transforming growth factors, mesodermal growth factors, transferrin, tumor necrosis factor, neuronotrophic factors, angiogenic factors, and antiangiogenic factors. Growth factors, especially transforming growth factor-beta, have a crucial role in directing the migration and developmental patterns of the cranial neural-crest cells that contribute extensively to the structures of the eye. Some growth factors also exert an effect on the developing ocular tissues by influencing the synthesis and degradation of the extracellular matrix. The mRNAs for the growth factors that are involved in the earliest aspects of the growth and differentiation of the fertilized egg are supplied from maternal sources until embryonic tissues are able to synthesize them. Subsequently, the developing eye tissues are exposed to both endogenous and exogenous growth factors that are derived from nonocular tissues as well as from embryonic fluids and the systemic circulation. The early interaction between the surface head ectoderm and the underlying chordamesoderm confers a lens-forming bias on the ectoderm; later, the optic vesicle elicits the final phase of determination and enhances differentiation by the lens. After the blood-ocular barrier is established, the internal milieu of the eye is controlled by the interactions among the intraocular tissues; only those growth factors that selectively cross the barrier or that are synthesized by the ocular tissues can influence further development and differentiation of the cells. An understanding of the tissue interactions that are regulated by growth factors could clarify the precise mechanism of normal and abnormal ocular development.     

Abnormal development of the os penis in male mice treated neonatally with tamoxifen

The os penis of male C57BL/Tw mice given 5 daily injections of 100 micrograms tamoxifen (Tx) starting on the day of birth (day 0) was examined at ages of 5-60 days; the bones of males given Tx injections for 5 days starting at 0-10 days and of those given neonatal injections of 100 micrograms clomiphene or nafoxidine were examined at 60 days. In the control males given the vehicle alone, the proximal segment of the os penis, composed of a compact cell mass found at day 0, developed at 5 days into the membrane bone with bone marrow and hyaline cartilage; the distal segment, composed of mesenchymatous cells until 10 days, developed at 30 days into fibrocartilage characterized by a distribution of type I collagen. By contrast, in Tx mice, fibrocartilage in the distal segment, and hyaline cartilage characterized by a distribution of type II collagen, and bone marrow in the proximal segment disappeared by 30 days. The maximum area of the proximal and distal segments gradually increased with age in control mice, whereas the proximal segment area remained unchanged in Tx mice. In clomiphene and nafoxidine mice at 60 days, the proximal segment was composed of hyaline cartilage; however, the distal segment lacked fibrocartilage. Hyaline cartilage in the proximal segment and fibrocartilage in the distal segment disappeared in all 60-day-old mice given Tx starting within 5 days. Neonatal castration did not suppress the formation of bone marrow and fibrocartilage in the os penis, though the bone size was smaller than in the intact controls. Formation of spines on the glans penis skin was suppressed by Tx given within 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)     

The os penis of the rat. I. Phosphomonoesterases in its proximal growth cartilage

The distribution of reaction for acid and alkaline phosphatases in the proximal cartilage of the os penis and the mandibular condylar cartilage has been compared. The distribution of acid phosphatase in the two structures seems to be identical, whereas the distribution of alkaline phosphatase in the os penis cartilage seems to differ from that in the mandibular condylar cartilage and, by this, from all other studied growth cartilages.     

Effect of poly(3-hydroxyalkanoates) as natural polymers on mesenchymal stem cells

Mesenchymal stem cells (MSCs) are stromal multipotent stem cells that can differentiate into multiple cell types, including fibroblasts, osteoblasts, chondrocytes, adipocytes, and myoblasts, thus allowing them to contribute to the regeneration of various tissues, especially bone tissue. MSCs are now considered one of the most promising cell types in the field of tissue engineering. Traditional petri dish-based culture of MSCs generate heterogeneity, which leads to inconsistent efficacy of MSC applications. Biodegradable and biocompatible polymers, poly(3-hydroxyalkanoates) (PHAs), are actively used for the manufacture of scaffolds that serve as carriers for MSC growth. The growth and differentiation of MSCs grown on PHA scaffolds depend on the physicochemical properties of the polymers, the 3D and surface microstructure of the scaffolds, and the biological activity of PHAs, which was discovered in a series of investigations. The mechanisms of the biological activity of PHAs in relation to MSCs remain insufficiently studied. We suggest that this effect on MSCs could be associated with the natural properties of bacteria-derived PHAs, especially the most widespread representative poly(3-hydroxybutyrate) (PHB). This biopolymer is present in the bacteria of mammalian microbiota, whereas endogenous poly(3-hydroxybutyrate) is found in mammalian tissues. The possible association of PHA effects on MSCs with various biological functions of poly(3-hydroxybutyrate) in bacteria and eukaryotes, including in humans, is discussed in this paper.     

Trafficking and differentiation of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a heterogeneous population of stem/progenitor cells with pluripotent capacity to differentiate into mesodermal and non‐mesodermal cell lineages, including osteocytes, adipocytes, chondrocytes, myocytes, cardiomyocytes, fibroblasts, myofibroblasts, epithelial cells, and neurons. MSCs reside primarily in the bone marrow, but also exist in other sites such as adipose tissue, peripheral blood, cord blood, liver, and fetal tissues. When stimulated by specific signals, these cells can be released from their niche in the bone marrow into circulation and recruited to the target tissues where they undergo in situ differentiation and contribute to tissue regeneration and homeostasis. Several characteristics of MSCs, such as the potential to differentiate into multiple lineages and the ability to be expanded ex vivo while retaining their original lineage differentiation commitment, make these cells very interesting targets for potential therapeutic use in regenerative medicine and tissue engineering. The feasibility for transplantation of primary or engineered MSCs as cell‐based therapy has been demonstrated. In this review, we summarize the current knowledge on the signals that control trafficking and differentiation of MSCs. J. Cell. Biochem. 106: 984–991, 2009. © 2009 Wiley‐Liss, Inc.     

Mesoangioblasts--vascular progenitors for extravascular mesodermal tissues

Mesoangioblasts are multipotent progenitors of mesodermal tissues that express the key marker of angiopoietic progenitors, Flk1 (VEGF-receptor 2), and are physically associated with the embryonic dorsal aorta in avian and mammalian species. When transplanted in vivo, they give rise to multiple differentiated mesodermal phenotypes. Their ability to extensively self-renew in vitro, while retaining multipotency, qualifies mesoangioblasts as a novel class of stem cells. Mesoangioblasts disclose not only an unexpected source of progenitors for skeletal muscle and a variety of other mesoderm-derived tissues, but also establish a lineage kinship between progenitors of vascular and extravascular mesodermal tissues, with important basic and applicative implications.     

Bidirectional induction toward paraxial mesodermal derivatives from mouse ES cells in chemically defined medium

Embryonic stem cells (ESCs) are a renewable cell source of tissue for regenerative therapies. The addition of bone morphogenetic protein 4 (BMP4) to serum-free ESC cultures can induce primitive streak-like mesodermal cells. In differentiated mouse ESCs, platelet-derived growth factor receptor-α (PDGFR-α) and E-cadherin (ECD) are useful markers to distinguish between paraxial mesodermal progenitor cells and undifferentiated and endodermal cells, respectively. Here, we demonstrate methods for BMP4-mediated induction of paraxial mesodermal progenitors using PDGFR-α and ECD as markers for purification and characterization. Serum-free monolayers of ESCs cultured with BMP4 could efficiently promote paraxial mesodermal differentiation akin to embryonic mesodermal development. BMP4 treatment alone induced paraxial mesodermal progenitors that could differentiate into osteochondrogenic cells in vitro and in vivo. Furthermore, early removal of BMP4 followed by lithium chloride (LiCl) promoted the differentiation to myogenic progenitor cells. These myogenic progenitors were able to differentiate further in vitro into mature skeletal muscle cells. Thus, we successfully induced the efficient bidirectional differentiation of mouse ESCs toward osteochondrogenic and myogenic cell types using chemically defined conditions.     

Cellular dynamics and molecular control of the development of organizer-derived cells in quail-chick chimeras

Malformations affecting the nervous system in humans are numerous and various in etiology. Many are due to genetic deficiencies or mechanical accidents occurring at early stages of development. It is thus of interest to reproduce such human malformations in animal models. The avian embryo is particularly suitable for researching the role of morphogenetic movements and genetic signaling during early neurogenesis. The last ten years of research with Nicole Le Douarin in the Nogent Institut have brought answers to questions formulated by Etienne Wolff at the beginning of his career, by showing that Hensen's node, the avian organizer, is at the source of all the midline cells of the embryo and ensures cell survival, growth and differentiation of neural and mesodermal tissues.     

A modified wire-loop method for quantitative electron microscopic radioautography

Summary The distribution of reaction for acid and alkaline phosphatases in the proximal cartilage of the os penis and the mandibular condylar cartilage has been compared. The distribution of acid phosphatase in the two structures seems to be identical, whereas the distribution of alkaline phosphatase in the os penis cartilage seems to differ from that in the mandibular condylar cartilage and, by this, from all other studied growth cartilages.     

Ectodermal factor restricts mesoderm differentiation by inhibiting p53

During gastrulation of the amphibian embryo, specification of the three germ layers, endo-, ecto-, and mesoderm, is regulated by maternal and zygotic mechanisms. Although it is known that mesoderm specification requires the cooperation between TGF-beta signaling and p53 activity and requires maternal factors, essential zygotic factors have been elusive. Here, we report that the Zn-finger protein XFDL156 is an ectodermal, zygotic factor that suppresses mesodermal differentiation. XFDL156 overexpression suppresses mesodermal markers, and its depletion induces aberrant mesodermal differentiation in the presumptive ectoderm. Furthermore, we find that XFDL156 and its mammalian homologs interact with the C-terminal regulatory region of p53, thereby inhibiting p53 target gene induction and mesodermal differentiation. Thus, XFDL156 actively restricts mesodermal differentiation in the presumptive ectoderm by controlling the spatiotemporal responsiveness to p53.     

Ventral arc of the os pubis: anatomical and developmental considerations

The ventral arc is a ridge of bone which may occur on the ventral surface of the corpus of the os pubis in adult females. Recently, this feature of the human public bone has regained attention as being of value in ascribing sex. The ventral arc should not be confused with a somewhat similar crest that can occur in adult males, which is characterized by a different position and configuration than that of the ventral arc. The corpus is the site of both muscular and ligamentous attachments. The tissues correlated with adult bony morphology and its development in females and males during growth are described. The primary research question addresses the factors involved in the determination of bony differences between the sexes. Sexual dimorphism in bony features of the ventral aspect of the human os pubis relates to muscular origin and to differential growth patterns between males and females.