part of anatomical structure formation involved in morphogenesis mammary gland morphogenesis mammary gland formation dph GO:0060592 mammary placode formation 2009-05-13T08:47:52Z The process pertaining to the initial formation of the mammary gland from unspecified parts. The process begins with formation of the mammary line and ends when the solid mammary bud invades the primary mammary mesenchyme. biological_process mammary bud formation mammary sprout formation mammary line formation