Integumentary System - Mammary Gland Development: Difference between revisions
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When an individual carries a mutation in either BRCA1 or BRCA2, they are at an increased risk of being diagnosed with breast or ovarian cancer at some point in their lives. Normal function of these genes was to participate in repairing radiation-induced breaks in double-stranded DNA. It is though that mutations in BRCA1 or BRCA2 might disable this mechanism, leading to more errors in DNA replication and ultimately to cancerous growth. (text modified from: NCBI genes and disease) | When an individual carries a mutation in either BRCA1 or BRCA2, they are at an increased risk of being diagnosed with breast or ovarian cancer at some point in their lives. Normal function of these genes was to participate in repairing radiation-induced breaks in double-stranded DNA. It is though that mutations in BRCA1 or BRCA2 might disable this mechanism, leading to more errors in DNA replication and ultimately to cancerous growth. (text modified from: NCBI genes and disease) | ||
:'''Links:''' [http://www.ncbi.nlm.nih.gov/omim/113705 OMIM - BRCA1] | :'''Links:''' [http://www.ncbi.nlm.nih.gov/omim/113705 OMIM - BRCA1] | [http://www.ncbi.nlm.nih.gov/omim/600185 OMIM - BRCA2] | ||
Revision as of 18:03, 22 September 2010
Introduction
The mammary gland is the functional structure of the female breast and develops initially as a skin specialization. Breast growth and appearance in male and female children are virtually identical prior to puberty. At puberty females, under the influence of mainly sex hormone signaling, undergo a series of growth changes. Breast growth after puberty is defined by the "Tanner Stages".
In pregnancy, an additional series of signals leads to further changes in breast structure. Finally at menopause, changes in sex hormone secretion can once again alter breast structure.
The breast also associated with oncogenesis (breast cancer). Research in this area has been aided by the discovery in 1994 of the two breast cancer susceptibility genes (BRCA1, BRCA2). There is some developing evidence that modification of stem cells (progenitor cells) that exist in the mammary gland may also contribute to neoplasms (cancer).
Mammary Glands Pregnancy
During pregnancy raised estrogens and progesterone stimulate gland development, secretory alveolar structures form and differentiate, leading to milk production in late pregnancy and milk secretion during lactation. Breasts are hemispherical in shape due to fat deposition. After birth, neonatal lactation supports further growth/development.
Abnormalities
Abnormalities occur in approximately 1% of female population and include in both sexes:
- polymastia - extra breast
- polytheli - extra nipple
- supernumerary nipple (relatively common in males)
- gynecomastia (Greek, gyne = woman, mastos = breast) is the excessive development of the male breast, which can occur transiently in puberty or due to other (hormonal) abnormalities.
Breast Cancer
In 1994, two breast cancer susceptibility genes were identified BRCA1 on chromosome 17 and BRCA2 on chromosome 13.
When an individual carries a mutation in either BRCA1 or BRCA2, they are at an increased risk of being diagnosed with breast or ovarian cancer at some point in their lives. Normal function of these genes was to participate in repairing radiation-induced breaks in double-stranded DNA. It is though that mutations in BRCA1 or BRCA2 might disable this mechanism, leading to more errors in DNA replication and ultimately to cancerous growth. (text modified from: NCBI genes and disease)
- Links: OMIM - BRCA1 | OMIM - BRCA2
