In humans, milk lines form as thickenings of the epidermis of the mammary ridge, along the front surface of both sexes. Milk lines appear in the seventh week of embryonic development before human sexual differentiation , which explains why male humans have nipples.

2023年12月10日 · Ectodermal thickenings, known as mammary ridges (milk ridge or milk line), emerge on the chest around the 4th intercostal space, giving rise to rudimentary mammary buds by the 5th week of gestation. These primary mammary buds extend downward, developing into secondary buds and intricate mammary lobules over the next 7 weeks.

2023年7月17日 · The milk line, which is a distinct linear elevation, appears around the seventh week. At the end of the eighth week, the rudimentary breast forms from the thickened white line and will eventually become the mature breast. Throughout embryogenesis, there is …

2025年1月21日 · The mammary gland is a specialized organ in mammals responsible for producing milk to nourish offspring. It is a modified sweat gland composed of glandular tissue, fat, and connective tissue. The mammary gland contains multiple lobes, each consisting of smaller lobules where milk is produced and secreted. Milk is carried through a network of ducts

2023年11月3日 · Structures of the female breast seen on a sagittal section and anterolateral view. The female breast in humans contain mammary glands that produce milk for nursing their young. The latin name for the breast is mamma, thus it is clear why we belong to the class of mammals together with many other animal species.

The development of the murine gland begins at embryonic day (E) 10 with the formation of bilateral stripes (milk lines) of multilayered ectoderm that run anterior-to-posterior from the forelimb bud to hindlimb bud on the ventral surface of the embryo. By E11.5, the mammary line resolves into five pairs of placodes at reproducible locations.

2022年2月1日 · It touches the lateral edge of the body of the sternum on its medial aspect, and the midaxillary line on its lateral aspect. Superiorly and laterally, projecting from its outer upper quadrant, is a tongue-like projection of breast tissue into …

2019年7月13日 · The breasts of an adult woman are always paired and develop from a line of glandular tissue found in the fetus and known as the milk line. This milk streak, or galactic band, develops from the axilla to the groin during the fifth week of embryonic life.

2021年3月16日 · The milk lines are two lines which run from the axilla to the medial thigh on each side. These paired mammary ridges usually atrophy after 6 weeks of embryonic age except at the pectoral location. Incomplete regression of the milk line results in an accessory nipple (polythelia) or breast tissue (polymastia) anywhere along this region.

In a 6-weeks-old human embryo an ectodermal ridge, known as the milk line or primary ridge, is noted. This thickening extends along the body wall on either side from the axilla to the groin. In the human it atrophies, but a small portion remains in each pectoral region, which becomes the mammary gland.