| Exocrine secretion |
| Merocrine or eccrine – byexocytosis |
| Apocrine – by membrane budding (loss of cytoplasm) |
| Holocrine – by membrane rupture |
Apocrine (/ˈæpəkrɪn/)[1] is a term used to classify the mode ofsecretion ofexocrine glands. In apocrine secretion, secretory cells accumulate material at theirapical ends, often formingblebs or "snouts", and this material thenbuds off from the cells, forming extracellularvesicles. The secretory cells therefore lose part of theircytoplasm in the process of secretion.
An example of true apocrine glands is themammary glands, responsible for secreting breast milk.[2] Apocrine glands are also found in the anogenital region andaxillae.[3]
Apocrine secretion is less damaging to the gland than holocrine secretion (which destroys a cell) but more damaging than merocrine secretion (exocytosis).
Apocrine metaplasia is a reversible transformation (metaplasia) of cells to an apocrinephenotype. It is common in the breast in the context offibrocystic change. It is seen in women mostly over the age of 50 years. Metaplasia happens when there is an irritation to the breast (breast cyst). Apocrine-like cells form in a lining of developing microcysts, due to the pressure buildup within the lumen. The pressure build up is caused by secretions.[5] This type of metaplasia represents an exception to the common rule of metaplasia increasing the risk for developing cancer in that apocrine metaplasia doesn't increase the possibility of developing breast cancer.[6] Metaplastic apocrine cells belong to the category ofoncocytes, which are a group characterized by abundantacidophilic, granular cytoplasm (from the Greek root onco-, which means mass, bulk).
Apocrine ductal carcinomain situ (ACDIS) is a very rare breast carcinoma which is regarded as a variant of theductal carcinoma in situ breast tumors. ACDIS tumors have microscopichistopathology features that are similar topure apocrine carcinoma of the breast tumors but differ from them in that they are completely localized, i.e. have not invaded nearby tissues or metastasized to distant tissues.[7]
Apocrinecarcinoma is a very rare form of female breast cancer. The rate of incidence varies from 0.5 to 4%.[8] Cytologically, the cells of apocrine carcinoma are relatively large, granular, and it has a prominenteosinophilic cytoplasm.[9] When apocrine carcinoma is tested as a“triple negative", it means that the cells of the patient cannot express theestrogen receptor,progesterone receptor, orHER2 receptor.[10]
{{cite web}}: CS1 maint: multiple names: authors list (link) Last author update: 28 May 2020.