Development === :::success > Documentation [name=MrDr.Staffan] ###### tags: `page` `development` `shh` ::: :::info ## Table of Contents [TOC] ::: [Top](#Table-of-Contents) --- # SHH ## Genes [Top](#Table-of-Contents)  Uniprot SUFU SUFU Negative Regulator Of Hedgehog Signaling SHH Wnt Hedgehog Notch Gli1 Signaling by Hedgehog and cAMP signaling pathway ## SHH signaling [Top](#Table-of-Contents) --- ## Disease [Top](#Table-of-Contents) “All these genes that are coupled to metabolism that might patterned by SHH” “Its a midline disease, then our prediction would be that these patients have problems with metabolism” Do they? --- ### Smith-Lemni-Opitz syndrome - SLOS [Top](#Table-of-Contents) Wiki: Biochemical phenotype Given that SLOS is caused by a mutation in an enzyme involved in cholesterol synthesis, the resulting biochemical characteristics may be predictable. Most patients have lowered plasma cholesterol levels (hypocholesterolemia). However, approximately 10% may show normal cholesterol levels, and decreased concentrations of cholesterol are not solely indicative of SLOS. Increased levels of cholesterol precursors are also common in SLOS. In particular, elevated levels of 7-dehydrocholesterol are fairly specific to SLOS SLOS is an autosomal recessive disorder.[6] More than 130 different types of mutations have been identified __DHCR7__ cholesterol-7-dehydrogenase / 7-Dehydrocholesterol reductase Its expression is induced by decreased sterol concentrations via sterol regulatory binding proteins (SREBP). Missense mutations (single nucleotide change resulting in a code for a different amino acid) are the most common, accounting for 87.6% of the SLOS spectrum. These typically reduce the function of the enzyme but may not inhibit it completely DHCR7 is most efficient at reducing 7DHC, but it is known to reduce the carbon 7 double bond of other sterols, indicating a range of substrate specificity. 7-Dehydrocholesterol is a toxic steroidal metabolite that accumulates in the bodies of those with SLOS Smith-Lemni-Opitz syndrome ---  In early human fetal development, webbing (__syndactyly__) of the toes and fingers is normal. At about 6 weeks of gestation, apoptosis takes place due to a protein named sonic hedgehog, also known as SHH, which dissolves the tissue between the fingers and toes, and the webbing disappears. In some fetuses, this process does not occur completely between all fingers or toes and some residual webbing remains. ### Joubert Syndrome [Top](#Table-of-Contents) Type JBTS19 - mutated ZNF423 Autosomal dominant Type JBTS1 - mutated INPP5E Autosomal recessive ::: warning <b> apapapapapapapa</b> ::: ::: info asdapapdfklasf ::: :hamster: # Embryology - Neurulation [Top](#Table-of-Contents) [](https://www.youtube.com/watch?v=vvBBFOu9h1w)    [](https://www.youtube.com/watch?v=4Swn8_Jnlss) Embryology of the Pharyngeal Arches https://www.youtube.com/watch?v=l5iGrX5hIvM Alar plate (floor plate)  https://www.youtube.com/watch?v=VrTatTIIRNU Cerebellum1  Cerebellum2  Face [ ](https://www.youtube.com/watch?v=cVPMjE2UA70) Facial features defined by neural crest cells [# Memories as being the path through the hippocampus. On the way activating different brain regions. Note: 1. Fornix becomes hippocampus. 2. Rostral hippocampus is in the middle of the arch.  Path through hippocampus etc.  # Human Timeline [Top](#Table-of-Contents) D3 Blastocystdas D5 - Implanation of blastocyst into uteruine wall D18 Groove and Neural fold. D20 First somites D21 Heart cardiogenesis, week 3 begins as paired heart tubes. D23 - Heart begins to beat in Humans by day 22-23, first functioning embryonic organ formed D24 Thyroid - thyroid median endodermal thickening in the floor of pharynx D24 Ventricular Optic ventricle appears D25 neural crest vagal neural crest enter the foregut (20-25 somite stage)' W4   D28 pituitary Week elongation, contacts infundibulum, diverticulum of diencephalon ' w4 - Facial region - formation of five facial swellings 1. Frontonasal- 2&3. Maxillary- and 3&4 Mandibular prominences.Structures are formed from the migration &prolifration of CNCC from different parts of the neural tube w5. Nasa placodes and optic placodes develop. heart Week 5 septation starts, atrial and ventricula 6w the mandibular pairs form the outline of upper and loer 7w border of nostril and upper lip 7w most facial structures can be observed. # Extra-CNS tissues [Top](#Table-of-Contents) ![Uploading file..._d5vd9yfvq]() # Ganglionic Eminence  Coronal section in the forebrain of an embryonic mouse at 12.5 days of gestation (preplate stage) (LGE, MGE) from which GABAergic interneurons tangentially migrate to the cortical anlage (left, yellow) Glutamatergic neurons destined for the cortex are generated locally in the cortical ventricular zone and migrate radially (right, red) # Axon Guidance https://en.wikipedia.org/wiki/Axon_guidance ## Adipose [Top](#Table-of-Contents)  ## Syndetome [Top](#Table-of-Contents)  https://discovery.lifemapsc.com/in-vivo-development/somite # Cell & Tissue Lineage Overview [Top](#Table-of-Contents)