Faculty of Biological Science and Technology Zoology and Botanical department Practical embryology Amphibian development (4 mm larvae; sagittal sections) By: Shirin Kashfi Ph.D in Animal Development [email protected] tail bud stage At the time of neurulation termination, a part which is known as tail bud develops in the end of embryo body The entire body elongate and shorten in dorso-ventral direction in some extend First muscular responses to external stimuli develop, so this stage refer as muscular response stage too Tail bud is elongated and contains neural tube, notochord and unsegmented mesoderm as well as dorsal and ventral tail fin Five primary brain vesicles are developed (telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon) Retina (neural retina and retinal pigmented epithelium) and lens placode are formed Auditory vesicle in associated with hind brain and olfactory placode in associated with forebrain (telencephalon) are developed Heart rudiment is developed below to pharynx from mesoderm Foregut, midgut and hindgut are formed. In foregut oral cavity are expanded ventrally and laterally, pharynx and liver diverticulum can be recognizable Pronephric kidney is developed from intermediate mesoderm Somites are formed stage 18, 96 hpf, 4 mm in all sections please consider anterior, posterior, dorsal and ventral directions surface ectoderm yolky endoderm yolky endoderm can be seen in these sections gradually head region is appeared From: embryo/amphibian development/Book - The Frog Its Reproduction and Development 2 - Embryology.htm Neuroepithelium can be seen if section pass through neural tube surface pharyngeal arch neural tube (prosencephalon) pharynx optic vesicle (optic cup forming) tail bud oral sucker somites rudiment حالت تکامل نیافته، شکل اولیه Placode auditory vesicle ضخیم شدگي موضعي و موفت اکتودرم در ناحیه سر و گردن olfactory placode heart rudiment somites R M P surface ectoderm liver heart rudiment diverticulum P: prosencephalon; M: mesencephalon; R: rhombencephalon head mesenchyme proctodeum Proctodeum is the back ectodermal part of an alimentary canal. It is created during embryogenesis by a folding of the outer body wall. It will form the lower part of the anal canal Spinal cord Rhomben Mes notochord D T pharynx hind gut liver heart rudiment diverticulum T: telencephalon; D: diencephalon; Mes: mesencephalon; Rhomben: rhombencephalon name different part name different part mid gut epiphysis hind gut با عبور از برش ساجيتال مياني، دوباره به نيمه ديگر جنين مي رسيم که تصوير آينه اي نيمه ديگر است notochord neuroepithelium somites olfactory placode tail bud optic cup oral sucker proctodeum auditory vesicle thyroid rudiment heart rudiment name different part .