Overview of the Mammary Gland

Cowie, A. T.

doi:10.1111/1523-1747.ep12677240

Cited by 44 publications

(44 citation statements)

References 24 publications

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“…The mammary gland is part of the reproductive system, lactation being the final part of the reproductive cycle (Cowie 1974). Hence, development of the mammary gland is closely related to the development of other reproductive organs, which are more closely related to body growth than to chronological age (Moran et al 1989;Schillo et al 1992).…”

Section: Discussionmentioning

confidence: 99%

Plane of nutrition and folic acid supplementation between birth and four months of age on mammary development of dairy heifers

Petitclerc¹,

Dumoulin²,

Ringuet³

et al. 1999

Can. J. Anim. Sci.

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. 1999. Plane of nutrition and folic acid supplementation between birth and 4 months of age on mammary development of dairy heifers. Can. J. Anim. Sci. 79: 227-234. Forty-seven dairy heifers of approximately 10 d of age were assigned randomly to a 2 × 2 factorial design to study the effects of folic acid supplementation (0 vs. 40 mg) administered weekly i.m. and levels of feed intake after weaning on mammary development. Folic acid treatment started immediately and all heifers were weaned 5 wk later. Heifers were then either fed ad libitum grass hay and concentrates or restricted to a body weight gain of approximately 700 g d -1 until slaughter at 4 mo of age. Average daily gain was affected by feed intake level after weaning (615 vs. 954 g d -1 ; P < 0.01); however, folic acid supplementation increased weight gain only during the 5-wk period following weaning (P < 0.05). Heifers fed ad libitum were 33 % heavier before slaughter (P < 0.001) but there was no effect due to folic acid supplementation (P > 0.05). There was no effect of treatments on serum prolactin and growth hormone concentrations (P > 0.05); overall, prolactin increased and growth hormone decreased over the 16-wk sampling period. However, serum IGF-1 concentrations were significantly higher in heifers fed ad libitum following weaning as compared with the feed-restricted animals (P < 0.001); overall, IGF-1 concentrations increased linearly between weeks 2 and 16 (P < 0.001). Plane of nutrition did not have any effect (P > 0.05) on the total volume of parenchymal tissue in the mammary gland (61.6 vs. 63.6 cm 3 ); however, ad libitum feeding increased significantly (P < 0.001) the volume of extraparenchymal tissue in the gland (262.0 vs. 1067.6 cm 3 ). After adjusting data for the difference in body weight at slaughter, the amount of parenchymal tissue was smaller in animals fed ad libitum (P < 0.05); this adjustment did not change the effect of plane of nutrition on mammary extraparenchymal tissue. In conclusion, a fast rate of gain after weaning up to 4 mo of age induced a large accumulation of mammary fat, but did not negatively affect the total amount of parenchymal tissue in the mammary gland of dairy heifers.Key words: Plane of nutrition, folic acid, mammary gland, IGF-1 Petitclerc, D., Dumoulin, P., Ringuet, H., Matte, J. et Girard, J. 1999. Taux de croissance et supplémentation en acide folique entre la naissance et l'âge de 4 mois sur le développement de la glande mammaire de génisses laitières. Can. J. Anim. Sci. 79: 227-234. Quarante-sept génisses âgées approximativement de 10 jours ont été distribuées aléatoirement selon un dispositif factoriel 2 × 2. Les deux facteurs étudiés ont été la quantité d'acide folique injectée i.m. par semaine (0 ou 40 mg) pendant 16 semaines et le niveau d'alimentation suivant le sevrage. Suite au sevrage, les génisses ont été alors alimentées à volonté de foin et de concentrés ou restreintes pour permettre un gain de poids moyen de 700 g jour -1 jusqu'à leur abattage à l'âge de quatre mois. Le gain moyen quot...

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Section: Discussionmentioning

confidence: 99%

Plane of nutrition and folic acid supplementation between birth and four months of age on mammary development of dairy heifers

Petitclerc¹,

Dumoulin²,

Ringuet³

et al. 1999

Can. J. Anim. Sci.

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“…Rabbits have four or five pairs of mammae (Lossi et al 2016) and approximately six ductal systems per mamma (Cowie, 1974), in contrast to mice, cattle, sheep, and goats, which have a single ductal system per gland (Rowson et al 2012). In this respect, the rabbit mammary gland more closely resembles the human breast, which has 4-18 ductal systems (Cowie, 1974;Love & Barsky, 2004;Ramsay et al 2005). This notable variation in the number of ductal systems, or galactophores, per mamma is due to developmental differences between species.…”

Section: Introductionmentioning

confidence: 99%

Sinus‐like dilatations of the mammary milk ducts, Ki67 expression, and CD3‐positive T lymphocyte infiltration, in the mammary gland of wild European rabbits during pregnancy and lactation

Hughes

Watson

2018

Journal of Anatomy

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Sinus‐like dilatations of the mammary duct are recognisable in the mammary gland of pregnant and lactating wild European rabbits. These dilatations exhibit a bilaminar epithelial lining, with luminal epithelial cells expressing basal and lateral E‐cadherin. Occasional binucleated mammary epithelial cells are present in the luminal layer. Underlying the luminal epithelial cells is a basal layer of cytokeratin 14‐positive cells, supported by a thin layer of fibrous tissue. Multi‐segmental epithelial proliferation, as indicated by Ki67 expression, is apparent in the luminal epithelial cells, suggesting a capacity for division during pregnancy and lactation. CD3‐positive T lymphocytes are present both intraepithelially, suggesting exocytosis, and in foci subjacent to the ductular epithelium. We consider that sinus‐like dilatations of the mammary duct may have the potential to give rise to a subset of the mammary gland neoplasms classified as ductal in origin. Milk accumulation in these sinus‐like dilatations is likely to provide a niche for bacterial replication in cases of mastitis in rabbits. These structures are an important component of the innate immune system of the mammary gland, both as a physical barrier and as an interface between the milk and mammary immune cells.

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“…Hormones such as prolactin and oxytocin play critical short-term roles in initiating and maintaining milk secretion. However, other hormones, such as progesterone, growth hormone, glucocorticoids, insulin, and estrogen, play important long-term roles by promoting structural remodeling and growth of mammary tissues (Linzell, 1959;Cowie, 1974). In particular, the markedly elevated estrogen levels of pregnancy induce epithelial cell proliferation, which is required for forming new ducts (Linzell, 1959;Foth and Cline, 1998;Raafat et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Estrogen increases calcitonin gene‐related peptide‐immunoreactive sensory innervation of rat mammary gland

Blacklock

Smith

2004

J. Neurobiol.

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Estrogen plays important roles in preparing mammary tissue for lactation. However, estrogen also influences innervation in some tissues. We examined the effect of estrogen on peripheral innervation of mammary tissues of ovariectomized adult virgin female rats. Seven days after ovariectomy, 17beta-estradiol or placebo pellets were implanted subcutaneously, and tissues were harvested 1 week later. Estrogen treatment decreased mammary gland mass and adipocyte content, while ductal content increased and vascular composition was unaffected. Estrogen increased total areas occupied by nerves in mammary gland sections immunostained for the pan-neuronal marker protein gene product 9.5, and this increase persisted after normalizing for treatment-induced differences in gland mass. Although a significant increase in tyrosine hydroxylase-immunoreactive sympathetic nerve area was observed, no difference was detected following correction for differences in gland size, implying a conserved number of sympathetic nerves in the face of reduced gland volume. Calcitonin gene-related peptide-immunoreactive sensory nerve sectional area was also increased, and corrected nerve area remained 88% greater, indicating nerve proliferation during estrogen treatment. Total, sensory, and sympathetic innervation of the nipple and adjacent dermal tissue were unaffected by estrogen. We conclude that chronic estrogen elevation induces selective proliferation of rat mammary gland calcitonin gene-related peptide-containing nerves, which are associated primarily with blood vessels and are probably nociceptors. Because they are likely to subserve a vasodilatory function, increased innervation may promote increased blood flow necessary for milk formation during suckling. Moreover, these findings may help explain abundant anecdotal reports of increased breast sensitivity in humans under high estrogen conditions.

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Overview of the Mammary Gland

Cited by 44 publications

References 24 publications

Plane of nutrition and folic acid supplementation between birth and four months of age on mammary development of dairy heifers

Plane of nutrition and folic acid supplementation between birth and four months of age on mammary development of dairy heifers

Sinus‐like dilatations of the mammary milk ducts, Ki67 expression, and CD3‐positive T lymphocyte infiltration, in the mammary gland of wild European rabbits during pregnancy and lactation

Estrogen increases calcitonin gene‐related peptide‐immunoreactive sensory innervation of rat mammary gland

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