has part has part has_part characteristic of part of has modifier mammary gland bud formation abnormal mammary gland embryonic development abnormal mammary gland bud formation abnormal milk bud formation any anomaly in the morphogenetic process in which a distinct bulb of epithelial cells forms from a mammary placode abnormal lactiferous gland bud formation MP:0013786 In mice, as the cells from the placode begin to invaginate into the underlying mesenchyme they pile up at the surface and begin to array themselves in a concentric orientation so that the early bud is elevated above the plane of the surrounding epidermis; as a result, at E12, the developing buds are visible as prominent knobs on the ventral surface of the embryo, which then submerge beneath the plane of the skin; the formation of the epithelial bud is accompanied by dramatic changes in the underlying mesenchyme; cells surrounding the epithelium elongate, condense, and orient their long axis in a radial fashion around the developing epithelial cells; at the end of this process, the mature bud consists of a sphere of concentrically arrayed epithelial cells connected to the skin surface by a stalk of epidermal-like cells; both ball and stalk are, in turn, surrounded by three to five layers of condensed mesenchyme, referred to as the primary mammary mesenchyme; in female mice the mammary buds remain relatively quiescent from E14 to E16, when ductal morphogenesis commences; in male mice, the mesenchyme around the stalk enlarges and condenses further, eventually severing the connection to the skin; this is followed by apoptosis of the mammary mesenchyme and many cells within the epithelial bud as well; consequently, male mice have either no mammary epithelial ducts or only very rudimentary ones. abnormal mammary bud formation quality abnormal