Germinal layers

(Biol.) the two layers of cells, the ectoblast and entoblast, which form respectively the outer covering and inner wall of the gastrula. A third layer of cells, the mesoblast, which is formed later and lies between these two, is sometimes included.

See also: Germinal

References in periodicals archive ?
Mature teratomas are designated grade 0, displaying mature and well-differentiated tissues belonging to all three germinal layers. Immature teratomas contain immature components from one of the germ cell layers most commonly neuroectodermal tissue, and are accordingly graded as 1 if this immature element is present only in one site in a slide, and grades 2 and 3 when present in < 4 and > 4 fields per slide, respectively.
(8-9) Teratomas are embryonic tumors that are derived from two to three germinal layers. Based on the presence of malignant elements they are categorized into mature and immature teratomas.
Teratomas are composed of derivatives of all three germinal layers, arranged in haphazard manner.
Microscopically, multiple sections of the specimen studied showed derivatives of all the three germinal layers in the form of adipose tissue, cartilage, cystic areas lined by simple cuboidal to stratified squamous epithelium and dermal appendages.
Background: Teratomas are usually derived from all the three germinal layers. They present as cysts filled with abundant sebaceous material with hair and may contain cartilage teeth and bone.
Histologically teratomas comprise of tissues from all the three germinal layers. The most common is ectoderm in the form of skin hair and abundant sebum.
Arising from all 3 germinal layers, teratomas are heterogeneous masses that may be intracranial or extracranial.
Imaging studies show a heterogeneous mass reflecting the presence of tissues from all 3 germinal layers and many contain calcification.
(5) In the case presented here, all 3 germinal layers were represented.
The company reports that during the past 2 years its scientists have successfully differentiated the cloned MLPCs into tissues representative of the 3 germinal layers, including neural stem cells, nerve cells, liver/pancreas precursors, skeletal muscle, fat cells, bone cells and blood vessels.
Figure 3 demonstrates the tumor histology, which shows derivatives of all 3 germinal layers. Mesodermal components were immature tooth buds (Figure 3, A), cartilage, bone, and skeletal muscle (not shown).
Dermoid cysts can be composed of elements descending from all three of the germinal layers, but in ovarian DCs, ectodermic differentiation frequently occurs.