Browsing by Subject "Human foetus"

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    Cytological aspects of the human adrenal cortex development in the course of intra-uterine life
    (Murcia : F. Hernández, 1993) Bocian-Sobkowska, J.; Malendowicz, L.K.; Wozniak, T.
    Stereological studies were performed on 20 pairs of adrenal glands of human foetuses. The volume of particular adrenocortical zones, average cell volume and number of parenchymal cells were calculated. In 50 to 320 mm crown-rump length (C.-R.L.) foetuses (9-38 weeks of the intra-uterine life) an exponential increase in adrenal gland weight was found. If compared with the earlier period, the rate of increase was evidently higher beginning from the 20th week and depended mainly upon enlargement of the foetal zone, with less marked changes in the glomerulosa-fasciculata zone. The zona glomerulosa (ZG) and the outer zona fasciculata (ZF) began to delineate by the 20th week of gestation. Zona reticularis was not observed in our material. From the beginning of development, fasciculata cell volume was markedly higher than that of ZG cells and lower than foetal zona (ZX) cells. Until the 20th week of intra-uterine life the volume of glomerulosa-fasciculata zone (G-FZ) increased at a slow rate, while the rate of increase in volume of ZX was higher. After 20 weeks the rate of increase in volume of al1 adrenocortical zones was markedly higher (the same as that of the stroma). The volume of stroma in ZX markedly exceeded that in the remaining parts of the cortex. The average cell volume of ZG and ZF remained constant during the foetal period, while the average cell volume of ZX cells increased gradually from the 9th to the 20th foetal week and afterwards remained unchanged. Of interest is the fact that the percentage of ZX cells in the gland remained rather constant during the whole period of observation (about 3540% for ZX and 60-65% for ZG and ZF).
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    Development of the dynamic structure force lines of the middle ear ossicles in human foetuses
    (Murcia : F. Hernández, 2008) Whyte, J.; Cisneros, A.; Yus, C.; Obón, J.; Whyte, A.; Serrano, P.; Pérez-Castejon, C.; Vera, A.
    Objectives: To study the ontogenic development of the organisation of the human middle ear ossicles structure. Material and methods: 46 human temporal bones of ages varying from 32 days postconception to newborns. Results: The development of the structural organisation of the malleus begins at 16 weeks via two cortical fascicles situated in the neck; at 21 weeks they extend towards the head, at 23 weeks to the lateral process and at 24 weeks to the handle. In the handle, the force lines are transmitted via three cardinal fascicles, two of them via the cortical fascicle and one via the centre, which starts after 29 weeks' development and is consolidated after 31 weeks. In the incus the force lines start at 16 weeks via two cortical fascicles situated in the long process, which progressively extend in a rostro-caudal direction between 17 and 20 weeks. At 21 weeks they occupy the whole extension of the long process and at 22 weeks the fusion of both cortical fascicles begins. From 30 weeks onwards it is strengthened by the crossing of bone trabeculae from one cortical to another. Two fascicles come out of the incus body, surrounding the medullary cavity and going in the direction of the short process. In the beginning, the stapes have two cortical fascicles in their crura. The remodelling process makes the internal cortical fascicle disappear and after 31 weeks all the force lines run through the external cortical fascicle. The tympanic membrane of the stapes footplate undergoes a remodelling process and after 28 weeks bony trabeculae are deposited. In newborns (40 weeks), the ossicles’ structure is cavitary and has not been completed. The fan-shaped trabecular fascicle, which starts in the articular facets of the malleus and the incus, still has to develop.