The authors attributed this finding to the "overlapping features" of urothelial and prostate tissue, since both are embryologically
derived from the urogenital sinus, explaining that, as such, some tumors cannot be definitively classified into either category.
, the carotid arteries originate in the third aortic arch and the dorsal aorta.
, they are considered to be similar in etiology to an encephalocele without intracranial linkage.
, the pituitary gland has 2 origins.
17) The thyroid gland, the first endocrine gland to develop embryologically
, arises from an endodermal thickening of the ventral floor of the pharynx as an invagination of the first pharyngeal pouch.
, haematopoietic stem cells arise in the yolk sac and many M-NSGCTs contain yolk sac elements.
1,3,9,10) However, tumors arising from the posterior and lateral walls of the bladder (which do not embryologically
arise from mesonephric remnants) have also been reported, (11,12) and this may be the basis for the second theory, which assumes that CCA of the urinary bladder is a variant of vesical adenocarcinoma that may originate from aberrant mullerian remnants, much like clear cell carcinomas of the uterus, vagina, and fallopian tube.
, it is thought to be due to failure of the cleavage of the metanephrons as they ascend out of the pelvis, shifting their blood supply from the iliac branches to segmental aortic branches, to their definitive lumbar position.
Auricular anomalies can be categorized embryologically
as malformational or deformational.
Traditionally, the exocrine and endocrine components of the pancreas have been viewed as distinct morphologically, embryologically
, and functionally, to the extent that most authors have addressed only one component or the other.
, the endodermal diverticula of the foregut gives rise to both the lungs and the liver, which are in close proximity to one another between weeks 3 and 8 of development (during which time a connection between the thoracic and abdominal cavities is usually present).
, the labia minora develop from the urethral folds, while the labia majora develop from the labioscrotal folds.