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