Amphibians: in sections

This page presents micrographs and explanations on a number of characteristic stages of the embryonic development in the common frog (formerly Rana esculenta, nowadays Pelophylax sp.) and the tadpole (Xenopus laevis) viewed in stained cross sections.
 

Early developmental stages in the common frog) sections)
A. Blastula An = Animal pole, Veg = Vegetal pole, 1 = Micromeres, 2 = Macromeres, 3 = Marginal zone, 4 = Blastocoel	B. Gastrulation: yolk plug stage An = Animal pole, Veg = Vegetal pole, 1 = Ectoderm, 2 = Dorsal blastoporus lip, 3 = Yolk plug in blastoporus, 4 = Ventral blastoporus lip, 5 = Remnants of blastocoel
C. Neurulation: neural plate 1 = Neural plate (just before the folding), 2 = Area of chorda mesoderm, 3 = Endoderm, 4 = Ectoderm, 5 = Mesoderm, 6 = Yolk material, 7 = Archenteron	D. Neurula stage: neural groove 1 = Neural fold, 2 = Chorda, 3 = Ectoderm, 4 = Yolk material, 5 = Lateral plate mesoderm, 6 = Endoderm, 7 = Dorsal mesoderm (somites)
E. Neurula stage: neural tube 1 = Neural tube, 2 = Chorda, 3 = Area of intermediate mesoderm, 4 = Lateral plate mesoderm, 5 = Remnants of fertilization membrane, 6 = Archenteron, 7 = Endoderm, 8 = Somite mesoderm

 

Larval developmental stages in the tadpole (sections)
It is recommended to study these images along with the textbook: Atlas of descriptive embryology. Gary C. Schoenwolf. Pearson, Benjamin Cummings eds. ISBN 978-0-13-158560-7
Larval stage: heart region: Ref. figure in textbook (7th edition): 6.36 1 = Rhombencephalon, 2 = Chorda, 3 = Intestine, 4 = Heart region, 5 = Pericardial cavity, 6 = Heart tube, 7 = Endocardum, 8 = Myocardum, 9 = Fixation artifacts
Larval stage: tail region: Ref. figure in textbook (7th edition): 6.38 1 = Ectoderm (epidermal), 2 = Neural tube, 3 = Chorda, 4 = Mesoderm, 5 = Endoderm cells filled with yolk, 6 = Somite
Larval stage: head region / formation of the eye: Ref. figure in textbook (7th edition): 6.47 and 6.48 1 = Neural tube (detail rhombencephalon), 2 = Chorda, 3 = Retina, 4 = Lens, 5 = Cornea, 6 = Ectoderm (epidermis), 7 = "Adhesive gland", 8 = Foregut, 9 = Diencephalon, 10 = Developing eye
Larval stage: Ref. figure in textbook (7th edition): 6.49 and 6.52 (here sectioned obliquely in L-R profile) 1 = Neural tube (spine), 2 = (Somite) derma myotome, 3 = (Somitet)sclerotome, 4 = Chorda, 5 = Ectoderm (epidermal), 6 = Yolk, 7 = (probably) Ear vesicle