> For the complete documentation index, see [llms.txt](https://thisispiggy.gitbook.io/my-wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://thisispiggy.gitbook.io/my-wiki/01-step-1/reproductive/breast.md).

# Breast

## Embryogenesis

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Mammary%20gland%20made%20from/README.md)Milkline/crest forms during 4th week. Milklines are formed from thickening of epidermis.. ![](https://f001.backblazeb2.com/file/wikiFiles/sem4yrO.jpg)

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Layers%20of%20epidermis/README.md)Layers of epidermis:.. ![](https://f001.backblazeb2.com/file/wikiFiles/XM9ElNG.jpg)

### Germ layers

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Germ%20layers%20development%20of%20mammary%20gland%20duct%20epithelial%20cells%20and%20myoepithelial%20cells/README.md)**Epidermis** downgrowth into dermis. Ductal epithelial cells that make milk made from **basalis** layer of epidermis. Myoepithelial cells that contract to secrete milk made from **mesenchymal** (fibroblasts, mesoderm) around ducts.. ![](https://f001.backblazeb2.com/file/wikiFiles/YJbOm2C.jpg) Anything with milk production made by ectoderm ![](https://f001.backblazeb2.com/file/wikiFiles/1wm0bix.jpg)

## Anatomy

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Milk%20production,%20storage%20locations/README.md)Milk produced in the **alveolus** and stored in the **lactiferous sinus**. Contraction of myoepithelial cells forces milk out of the nipple. There are 9-10 lactiferous ducts per breast..

![](https://f001.backblazeb2.com/file/wikiFiles/DJo0cJx.jpg)

![](https://f001.backblazeb2.com/file/wikiFiles/iM8QMjS.jpg)

### Glands of Montgomery

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Glands%20of%20Montgomery%20are,%20function/README.md)Sebaceous glands of breasts. No hair follicles. Secretes lipoid substances that keep the breast moist., ![](https://f001.backblazeb2.com/file/wikiFiles/zLzPt8r.jpg)

### Blood Supply

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Blood%20supply%20to%20breast/README.md) Anterior intercostal.. ![](https://f001.backblazeb2.com/file/wikiFiles/oLEuGbT.jpg)

### Lymphatics

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Lymphatic%20drainage%20to%20breast/README.md).. ![](https://f001.backblazeb2.com/file/wikiFiles/bcVpbi9.jpg)

### Estrogen

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Estrogen%20stimulates%20what%20breast%20development%20and%20when/README.md)stimulates lactiferous duct growth and breast tissue enlargement at puberty.,

### Progesterone

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Progesterone%20stimulates%20what%20breast%20development/README.md)stimulates formation of secretory alveoli that produces the milk., ![](https://f001.backblazeb2.com/file/wikiFiles/ZDEgsBr.jpg)

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Where%20do%20estrogen/progesterone%20come%20from%20during%20ovulation%20and%20pregnancy?/README.md)Estrogen and progesterone produced from **follicle, corpus leuteum** during ovulation, and from **syncytiotrophoblast of placenta** during pregnancy.. ![](https://f001.backblazeb2.com/file/wikiFiles/ZDEgsBr.jpg)

## Lactogenesis

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Stages%20of%20milk%20production%20and%20time/README.md)Stages of milk production:

* **Lactogenesis**, stage 1, late pregnancy: Alveolar cells differentiated from secretory cells and begin producing **colostrom** (fore milk), clear fluid of high protein/mineral concentration and low fat content
* **Stage 2**, 2-3 days after birth: **Colostrum switches to milk production** (hind milk), higher fat content
* **Galactopoiesis**, 9 days after: Milk production/secretion maintained by supply and demand
* **Involution**, 40 days after: Milk production decrease as supplement added..

![](https://f001.backblazeb2.com/file/wikiFiles/DYWHKCp.jpg)

### Prolactin

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20is%20secreted%20by%20what%20cells%20of%20the%20brain%20and%20function/README.md)Secreted by lactotrophs of the anterior pituitary and stimulates **milk production** as well as the **development of milk-producing breast lobules**.,

![](https://f001.backblazeb2.com/file/wikiFiles/dt3I1Bs.jpg)

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20aka/README.md) Aka **luteotropin**.,

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20produced%20by/README.md) Is a hormone named because of its role in lactation, and it is produced by:

* **Maternal adenohypophysis**
* **Fetal adenohypophysis**
* **Decidual tissue of the uterus**..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/3%20Major%20actions%20of%20prolactin/README.md)**3 major actions:**

* Proliferation of mammary ducts at puberty and during pregnancy (with help of estrogen and progesterone).
* Milk production and secretion in breast in response to suckling by inducing synthesis of milk components: lactose, casein (the protein of milk), and lipids.
* Negative feedback on the hypothalamus causes ↓ GnRH (LH and FSH decrease) → **inhibits ovulation.** (Lactation amenorrhea).,

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20inhibited%20by%20what%20hormones%20and%20when/README.md)During pregnancy the levels of prolactin, estrogen and progesterone increase. This **increases prolactin secretion** from lactotrophs. However, **estrogen and progesterone also down-regulate prolactin receptors, preventing lactation from occurring** during pregnancy. Also **dopamine**..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20and%20dopamine/README.md)

* Inhibited by **dopamine** via binding to **D2 receptors**
* Destruction of hypothalamus leads to high prolactin
* Prolactin feedback on hypothalamus: increases dopamine release..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/When%20does%20prolactin%20production%20increase/README.md)At parturition, there is a **precipitous drop in estrogen and progesterone**, and at that point prolactin receptors are no longer down-regulated, allowing the high levels of prolactin seen during pregnancy to take action, thereby triggering lactation to occur..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/What%20antibody%20is%20in%20milk?%20Function?/README.md)Secretory IgA antibody helps to reduce neonatal gut infections since neonates have underdeveloped gut immune system..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/What%20is%20requiresd%20to%20maintain%20milk%20production/README.md)**Suckling** is required to maintain milk production, because the **increased nerve stimulation** increases oxytocin and prolactin levels..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/What%20is%20letdown%20reflex?/README.md)The suckling infant stimulates hypothalamus to produce oxytocin that increases milk secretion. This is called **letdown reflex**..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Pathways%20that%20happen%20as%20result%20of%20letdown%20reflex/README.md)Reflex arc activates 3 areas:

* inhibit dopamine (prolactin increase)
* increase oxytocin secretion (contraction of breast myoepithelial cells)
* uterine contraction (pain)..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Prolactin%20and%20TRH/README.md)Prolactin is increased by TRH:..

![](https://f001.backblazeb2.com/file/wikiFiles/o5WgPKf.jpg)

### Oxytocin

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Oxytocin%20secreted%20by/README.md)A nonapeptide that is primarily produced by the **paraventricular nuclei** within the **hypothalamus**, and secreted from the posterior pituitary. Like ADH, oxytocin travels to the posterior pituitary via carrier proteins called neurophysins.,

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/ADH%20and%20oxytocin%20differ%20by/README.md)**Antidiuretic hormone** is homologous to oxytocin. These nonapeptides only differ in structure by two amino acids..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Oxytocin%20stimulas/README.md)The major stimulus for secretion is **suckling**. Other positive stimuli include **dilation of the cervix** and **orgasm**.,

![](https://f001.backblazeb2.com/file/wikiFiles/AttlsxC.jpg)

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Oxytocin%20effect/README.md)The primary effects are **milk ejection** and **uterine contraction.** Causes milk ejection by inducing **contraction of myoepithelial cells in the breast**.,

![](https://f001.backblazeb2.com/file/wikiFiles/AttlsxC.jpg)

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Oxytocin%20and%20bleeding/README.md)Clinical correlation: Oxytocin (Pitocin) can be given to **reduce postpartum bleeding** because it causes uterine contraction..

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Oxytocin%20SE/README.md)Can have several adverse effects. These include:

* **Hyponatremia and seizures** (due to anti-diuretic properties similar to antidiuretic hormone)
* **Subarachnoid hemorrhage**
* **Uterine rupture** in pregnant patients.,

[\_](https://github.com/thisispiggy/my-wiki/tree/601ff771dc2fac1318ae8b59435ac8485628fd81/01%20Step%201/Reproductive/Origination,%20and%20action%20of%20prolactin/oxytocin/README.md)..

|           | From                | Effect                                  |
| --------- | ------------------- | --------------------------------------- |
| Prolactin | Anterior pituitary  | milk synthesis                          |
| Oxytocin  | Posterior pituitary | milk contraction by myoepithelial cells |

![](https://f001.backblazeb2.com/file/wikiFiles/ZDEgsBr.jpg)