Játra, pankreas, plíce celé embryo Figure 4: Whole slide image of the H and E stained embryo slide used in the experiment. The training and test images were extracted from this image Vývoj jater K.S. Zaret, Nature Reviews Genetics 3, 499-512, 2002 The ventral foregut endoderm gains the competence to develop into various tissues as a result of the expression of transcription factors in the endoderm. These include Foxa proteins, as well as signals that affect the endoderm, including bone morphogenetic proteins (Bmps) that emanate from the adjacent cells of septum transversum mesenchyme (STM). b | During tissue specification, fibroblast growth factor (Fgf) signals from the cardiogenic mesoderm, perhaps in conjunction with Bmp signals from the STM, initiate the liver gene programme in proximal endoderm, as well as blocking that for pancreas. Ventral endoderm cells sufficiently distal to the cardiogenic mesoderm escape the latter inhibitory effect and initiate the pancreatic gene programme. Ventral foregut explants were found to initiate liver gene expression, if exposed to cardiogenic mesoderm or Fgfs, or initiate pancreatic gene expression in the absence of such effectors70. The ventral endoderm explant studies therefore indicate that the pancreatic programme is the default state for this domain of endoderm. After the hepatic endoderm has been specified, it begins to extend towards the midgut. This process is abetted by turning of the embryo from the 'gut out' position (see figure in Box 1) to the inward curve shown by the typical fetus. At the same time, the hepatic endoderm cells become columnar in shape. These transitions seem to be elicited by signals that specify the endoderm (Fig. 2). Cells such as septum transversum mesenchyme (STM) cells and primitive endothelial cells, signalling molecules (such as Bmp, Hgf and Vegfr2) and transcription factors (such as Hex, Prox1, Hlx and c-Met) are essential to promote the morphogenesis of the liver bud itself (see b). b | Liver-bud morphogenesis is marked by the formation of the rostral diverticulum of the gut, remodelling of the extracellular matrix around the hepatoblasts and of E-cadherin-based connections between the cells, and proliferation and migration into the surrounding STM (beige). So, the hepatic endoderm (green) makes a transition from an epithelium to a non-polarized cell type during this period. Primitive endothelial cells, or angioblasts, appear near the hepatoblasts (a) and also promote outgrowth of the latter into the STM. During the outgrowth, the endothelial cells coalesce around spaces in the loose STM and create vesicles that fuse to form blood vessels (not shown). Haematopoietic cells then invade the growing liver and the organ becomes distinct from the gut epithelium. Bmp, bone morphogenetic protein; c-Met, HGF receptor; Hgf, hepatocyte growth factor; Vegfr2, vascular endothelial growth factor receptor 2. Magn. x40 Sinusoid Hepatocyty Gomori barvení - Retikulární vlákna (kolagen typ III, síť tvořící základ měkkých tkání) Játra Embryonální játra 14. t Magn. x40 Hematopoéza Sinusoid Hepatocyty do 9. měsíce iuv Vývoj pankreatu W.J. Larsen Human Embryology 2001 1. Otočení ventrálního základu – hlava pankreatu 2. Přiložení k dorzálnímu základu – ocas pankreatu 3. Splynutí vývodů Magn. x40 Langerhans. ostrůvky Exokrinní žláza Céva Vazivo Pankreas Embryonální pankreas 22. t Langer.ostrůvek od 8. týdne iuv Tubulus/acinus Mezenchym Magn. x40 Embryonální pankreas 8. t • vychlipují se z ventrální části předního střeva (endoderm) • D9.5 u myši a W4-5 u člověka • rostou a vyklenují se do obou pleurálních dutin v podobě rostoucích hrbolků pokrytých mezenchymální splanchnopleurou (pojivová část) • Vývoj plic http://www.ncbi.nlm.nih.gov Vacek Z. Embryologie, 2006 http://www.histology.leeds.ac.uk http://www.siumed.edu http://arcticboy.arcticboy.com/trachea-histology-pictures PLÍCE Magn. x10 Céva Alveolární tkáň Bronchus Plicní parenchym Embryonální plíce 11. t Magn. x40 Mukóza Submukóza Mezenchym Bronchus Celé embryo Choroidní plexus Telencefalon Oko Nosní dutina Základ zubu Jazyk Čelisti Páteř Mícha Srdce Plíce Žebra Játra Žaludek Střevo Metanefros+nadledvina Mesonefros+gonáda Pánev Dolní končetina