| Namespace | MPheno.ontology | Obsolete | false |
| description | any anomaly in the developmental process pertaining to the initial formation of the nipple sheath from the unspecified epidermis; in female mouse embryos, this process begins with a circular ingrowth of the epidermis around the origin of the mammary cord (mammary sprout) at E16.5 and ends before the underlying epidermis begins to elevate |