development of breast | development of mammary gland | developmentally anomalies of breast скачать в хорошем качестве

development of breast | development of mammary gland | developmentally anomalies of breast

The development of the breast occurs through distinct stages, influenced primarily by hormonal changes. These stages begin in fetal life and continue through puberty, adulthood, and various physiological conditions such as pregnancy and menopause. --- 1. Fetal Stage Formation of Mammary Ridges: Around the 4th to 6th week of gestation, mammary ridges (milk lines) develop, extending from the axilla to the groin. Primary Bud Formation: By the 6th to 8th week, the ridges regress except in the thoracic region, where they form primary mammary buds. Development of Secondary Buds: The primary buds branch into secondary buds, which later develop into lactiferous ducts. --- 2. Prepubertal Stage During childhood, the breast remains underdeveloped and consists mainly of ducts with minimal adipose and connective tissue. The nipple is flat, and the areola is poorly defined. --- 3. Pubertal Stage (Thelarche) Triggered by increasing levels of estrogen during puberty. Tanner Staging: Breast development is classified into five stages: 1. Stage 1: Prepubertal, no glandular tissue. 2. Stage 2: Breast bud formation; elevation of the nipple and a small mound of breast tissue. 3. Stage 3: Enlargement of the breast and areola without separation of contours. 4. Stage 4: Areola and nipple form a secondary mound above the breast tissue. 5. Stage 5: Mature breast with a single contour between the breast and areola. Ductal and Lobular Growth: Estrogen stimulates ductal elongation and branching, while progesterone promotes lobular and alveolar development. --- 4. Adult Stage The breast achieves its full size and shape, composed of: Glandular Tissue: Includes lobes, ducts, and alveoli. Adipose Tissue: Contributes to breast size and shape. Supportive Tissue: Cooper's ligaments provide structural support. --- 5. Pregnancy and Lactation During pregnancy, estrogen, progesterone, prolactin, and human placental lactogen stimulate: Proliferation of ducts and lobules. Enlargement of alveoli and increased vascularity. Development of the ability to produce milk. After childbirth, prolactin maintains milk production, while oxytocin facilitates milk ejection. --- 6. Menopause With the decline in estrogen, the glandular tissue atrophies and is replaced by adipose and connective tissue. Breasts may lose volume and elasticity, leading to sagging. --- Clinical Relevance Disorders of Development: Conditions like polymastia (extra breast tissue), polythelia (extra nipples), or amastia (absence of breast tissue) may arise. Hormonal Imbalances: Can lead to premature thelarche or delayed breast development. Breast Cancer: Hormonal influences during development can impact long-term breast health. Let me know if you'd like more detailed information on a specific aspect! #medical #medicalstudent #university #viralvideo #education #trending #bones #medicaldegree #neet