Browsing by Subject "Human fetus"

Now showing 1 - 4 of 4
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    A three-dimensional study of human fetal endocervix with special reference to its epithelium
    (Murcia : F. Hernández, 1998) Barberini, F.; Makabe, S.; Motta, P.M.
    The development of human fetal cervix has been systematically studied by SEM, obtaining a detailed map of its fine structure, particularly concerning the differentiation and maturation of the endocervical epithelium, including its "eversion" and "squamous metaplasia", normally occurring in postnatal life, but not yet observed in detail by electron microscopy in the fetus. Cervices from spontaneous abortion at 12, 15, 18, 20, 21 and 22 weeks and from intrauterine fetal death (hydrocephalus) at 31 weeks of development have been examined. At 12-15 weeks, as the canalization of the cervix proceeded, the endocervical epithelium consisted of high polyhedral cells, with regularly flattened or concave apices exhibiting scarce microvilli and often single primary cilia. Some narrow intercellular infoldings probably corresponded to primordial tubular glands. At the 18th week the epithelium was made up of a mosaic of flat or slightly raised polygonal cells, whose apical surface showed thin microplicae. At the 20th week a pseudostratified epithelium with many apically convex cells lined the cervical canal and the tubular glands. At 21 and 22 weeks "plicae palmatae" developed, covered by cells, often showing a smooth central area surrounded by microvilli, provided with a primary cilium and swollen by secretory material. This also formed rounded masses on the epithelium. In the lower part of the endocervix some very elongated cells showed short microplicae resulting from fusion of microvilli. At the 31st week secretion increased and its products spreading from the bottom of the glands contacted isolated ciliated cells at their openings and diffusely covered the surface epithelium. Most of the ectocervix exhibited squamous elements, with welldeveloped labyrinthine microplicae. These cells could overlap each other and also desquamate. The zone of the portio vaginalis around the OS of the cervical canal appeared infolded and hypertrophic. Here, an indented squamo-columnar junction between the ectocervical and endocervical epithelium, caused by tongue-like prolongations of squamous epithelium directed toward the endocervix, was found. Their tips consisted of elongated cells, rich only in short microvilli. Our data indicate that the features of the microvillous cells are an expression of a hormone-dependent differentiative process. Thus, their secretion might be stimulated by progesterone. Similarly microplicae on the ectocervical epithelium (a sign of squamous maturation) might be promoted by estrogens. Furthemore, two aspects were significative: 1) the finding - in an early phase only (18th week) - of endocervically-located squamous cells, although devoid of microplicae; and 2) the occurrence - in the latest phase (31st week) - of an indented squamo-columnar junction on the surface of the portio. These features are in agreement with the caudal shift of the squamo-columnar junction near the uterine cavity to the ectocervix after cervico-vaginal demarcation; the squamous metaplasia of this everted endocervical epithelium has been reported by some authors. It is likely that these processes, occurring in fetal life as well as in pregnant women, are related to a common hormonal background, arising from the mother to her fetus.
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    Morphometric studies on the development of the human thyroid gland. II. The late fetal life
    (Murcia : F. Hernández, 1997) Bocian-Sobkowska, J.; Wozniak, W.; Malendowicz, L.K.
    Histological and morphometric studies were performed on 27 thyroid glands obtained from normal fetuses ranging between 23 to 40 weeks of intra-uterine life. In the thyroids the volume of gland, colloid, and stroma were calculated by means of differential pointcounting method and the height of the thyroid follicular cells was measured. Moreover, the epithelium/colloid ratio in the thyroid gland, a very sensitive parameter of stimulation of the glands by TSH, was calculated. Regarding the values of this ratio in human fetal thyroid gland, the intra-uterine development of the gland may be divided into three distinct stages. The first one, between weeks 10- 18 is characterized by massive folliculogenesis and gradual accumulation of the colloid. The second stage, between weeks 19-29 of fetal life is characterized by rather unchanged values of epithelium/colloid ratio and the size of follicles. The third stage, after the 29th week of development is characterized by a gradual increase in the epithelium/colloid ratio and a decrease in the size of follicles.
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    Sequential pattern of nerve-muscle contacts in the small intestine of developing human fetus. An ultrastructural and immunohistochemical study
    (Murcia : F. Hernández, 1996) Fekete, Eva; Benedeczky, I.; Timmermans, J.P.; Resch, B.A.; Scheuermann, D.V.
    The developing enteric nervous system of the human fetus has been studied by means of electron microscopy and neuron-specific enolase immunocytochemistry between the 10th and 26th week of gestation, with special reference to the development of nervemuscle contacts. In the 10th week of gestation the circular muscle layer is formed, followed by the appearance of a primitive myenteric plexus, and the longitudinal smooth muscle layer in the 12th week of gestation. Adherens-type junctions between the smooth muscle cells and the elements of the myenteric plexus, interdigitation of nerve and muscle processes, and also contacts without any morphological specialization are frequent until the 18th week, when the mechanical points of attachment are relocated from the circular to the longitudinal muscle layer. By this time the developing myenteric plexus becomes ensheathed by non-neuronal cells, disrupting the direct contacts between smooth muscle cells and the primary strands of the myenteric plexus. The possible functional significance of these changing nerve-muscle contacts is discussed in the present paper.
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    Sialic acid expression in human fetal skeletal muscle during limb early myogenesis
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) Marini, Mirca; Sarchielli, Erica; Zappoli Thyrion, Giorgia Donata; Ambrosini, Stefano; Sgambati, Eleonora
    Investigations on animal models demonstrated that changes of sialic acid (SA) expression, particularly the polymeric form, in the skeletal muscle during embryonic and post-natal development seem to be related to muscle differentiation and functionality onset. The aim of this study was to evaluate the monomeric and polymeric SA expression in human skeletal muscle during early stages of fetal development, when important morphofunctional events occur. Specimens of fetal skeletal muscle from limb, between 9 and 12 weeks of gestation (wg), were obtained from 19 pregnant women. To investigate some morphofunctional features occurring during this development period, haematoxylin-eosin staining, tunel assay and immunohistochemistry for connexin-43 (Cx43) and parvalbumin were performed. SA expression and characterization was evaluated using lectin histochemistry (MAA, SNA, PNA, SBA, DBA), associated with enzymatic and chemical treatments. Polysialic acid (PSA) expression was also evaluated using immunohistochemistry. The results showed apoptotic myotubes between 9 and 10.5 wg, disappearing from 11 wg; Cx43 was more abundant in myotubes/myoblasts between 9 and 9.5 wg, decreasing and/or disappearing from 10 wg and parvalbumin was present in myotubes between 10 and 10.5 wg. PSA was revealed in myotubes/myoblasts from 9 to 10.5 wg; from 11 wg it was reduced or disappeared. Monomeric SA appeared in myotubes/myoblasts from 10 wg, increasing successively; acetylated SA was present from 11 wg. These findings demonstrated that changes in expression of various types of SA, occurring in human fetal skeletal muscle during early development, seem to be related to some morphofunctional aspects distinctive of this organogenesis crucial period.