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animal phys: 14-15
animal phys: 14-17
| Question | Answer |
|---|---|
| Mammary gland structure | support system = stroma intermarry groove Parenchyma |
| Stroma | contains collagen and elastin also includes blood and lymph vessels; ductal system |
| Intermammary groove | skin median suspensory ligament lateral suspensory ligament |
| Glandular system = parenchyma | responsible for milk synthesis and secretion |
| secretory units | alveoli = basic milk producing unit myoepithelial cells stimulated by oxytocin |
| pressure buildup between milkings | slows synthesis |
| teat anatomy and defence | keratin plug blocks bacteria smooth muscle sphincter closes canal poor teat conformation increases mastitis risk |
| blood supply | approx 400L of blood needs to circulate through udder to produce 1L of milk |
| Lymphatics and immunity | lymph nodes defend against infection good lymph flow reduces oedema risk destroy foreign substances and provide a source of lymphocytes to fight infection |
| Nerve supply | sensory nerves in a teat initiate milk let down reflex myoepithelial contraction driven by hormones |
| machine milking implications | shear forces remove keratin barrier increasing mastitis risk |
| mammary gland | modified sweat gland specialised for lactation highly vascular and metabolically active |
| Udder structure | 4 quarters Teats Storage structure Duct system |
| Teats | teat canal primary defence against infection lined with keratin plug post-milking to prevent entry of bacteria |
| Storage Structure | Gland cistern and teat cistern hold milk in between milkings |
| Duct system | Branching network connecting alveoli to cistern goes from alveoli, to small ducts, large ducts, grand cistern to the teat cistern |
| Alveoli | circular sacs lined with secretory epithelial cells surrounded by myoepithelial cells which contract in response to oxytocin supported by capillaries |
| Parenchyma | composed of alveoli, ducts, lobes, lobules, connective tissue |
| bloody supply to bovine mammary gland | enters via external pudendal arteries can exit via two routes external pudendal (pudic) veins subcutaneous abdominal veins |
| factors influencing lymphatic drainage | lactation stage inflammation and infection health and genetics management practices |
| Lactation stage (lymphatic drainage) | during early lactation when milk production is high, increased metabolic waste and immune cell activity can affect lymph flow |
| infection and inflammation (lymphatic drainage) | lymphatic drainage may be altered if the cow is fighting another infection such as mastitis |
| health and genetics (lymphatic drainage) | overall health of cow can affect lymphatic system |
| Management practices (lymphatic drainage) | milking frequency udder health management cow comfort can indirectly affect rate of lymphatic drainage |
| suspensory ligaments | median suspensory ligament lateral suspensory ligament |
| median suspensory ligament | allows for increase in udder size between milkings provides most of the strength to hold udder attached to ventral body wall |
| lateral suspensory ligament | white, fibrous collagen (inflexible) |
| alveolus | basic secretory unit; synthesises and/or secrets: lipids protein lactose minerals and vitamins water |
| mammogenesis | process of mammary gland development involves the growth and differentiation of mammary tissue to prepare for milk production |
| foetal mammary development day 30 | condensing ectodermal cells; start of mammary line |
| foetal mammary development day 35 | mammary line/crest;becomes mammary band |
| foetal mammary development day 43 | mammary bud; lenticular becomes spherical bud |
| foetal mammary developoemt day 65 | teat formation begins; female glands form conical structure |
| foetal mammary dveelopemtn day 80 | sprout forms; connected to mesenchyme; crown rump |
| foetal mammary development day 130 | teat cistern forms; canalisation progressing back to surface |
| foetal mammary development day 150 | streak canal formed; prepares for milk flow structure |
| pre-pubertal mammary development (birth - 2-3 months) | isometric growth increase in fat pad and connective tissue no alveoli yet parenchyma detectable by approx 75 days of age |
| pre pubertal mammary development (3-4 months - puberty) | allometric growth extensive ductal growth into fat pad no alveoli yet foundation of duct network determines future milk producing capacity |
| post pubertal development | triggered by oestrus cycle ovarian hormones + prolactin and GH early post-puberty: allometric growth if not pregnant = back to allometric growth |
| allometric growth begins | at 3-4 months and continues after puberty for a few months |
| isometric growth happens | for 2-3 months after birth |
| mammary gland development during pregnancy | pregnancy is a major stimulus to mammary growth allometric growth during pregnancy further duct growth during early stages |
| mammary gland development during lactation | mammary wet weights and DNA contents onctinue to increase during lactation high demand stimulates epithelial cell growth |
Created by:
sakelleher29