Zygote, fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells. zoom_in.
[edit on Wikidata] A melanocytic nevus (also known as nevocytic nevus) is a type of lesion that contains nevus cells (a type of melanocyte). Some sources equate the term mole with melanocytic nevus. Other sources reserve the term mole for other purposes. The majority of moles appear during the first two decades of a person's life, with about one in every 100 babies being born with moles.
A congenital nevus is a proliferation of benign melanocytes that is either present at birth or develops shortly afterwards. Congenital nevi are usually classified by size: small (less than 1.5 cm in diameter), medium (larger than 1.5 cm and up to 20 cm) or giant (measuring 20 cm in diameter or larger). This patient has a nevus spilus, a common benign melanocytic nevus with a speckled appearance. A nevus spilus can be macular or papular, exhibiting multiple smaller pigmented macules surrounding the central pigmentation. This lesion may be congenital or acquired and carries a small risk of malignant changes.