DOCSLIB.ORG

Anatomy of the Human Mammary Gland: Current Status of Knowledge

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Anatomy of the Human Mammary Gland: Current Status of Knowledge Clinical Anatomy 00:000–000 (2012) REVIEW Anatomy of the Human Mammary Gland: Current Status of Knowledge 1,2 1 FOTEINI HASSIOTOU AND DONNA GEDDES * 1Hartmann Human Lactation Research Group, School of Chemistry and Biochemistry, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia 2School of Anatomy, Physiology and Human Biology, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia Mammary glands are unique to mammals, with the specific function of synthe- sizing, secreting, and delivering milk to the newborn. Given this function, it is only during a pregnancy/lactation cycle that the gland reaches a mature devel- opmental state via hormonal influences at the cellular level that effect drastic modifications in the micro- and macro-anatomy of the gland, resulting in remodeling of the gland into a milk-secretory organ. Pubertal and post-puber- tal development of the breast in females aids in preparing it to assume a func- tional state during pregnancy and lactation. Remarkably, this organ has the capacity to regress to a resting state upon cessation of lactation, and then undergo the same cycle of expansion and regression again in subsequent pregnancies during reproductive life. This plasticity suggests tight hormonal regulation, which is paramount for the normal function of the gland. This review presents the current status of knowledge of the normal macro- and micro-anatomy of the human mammary gland and the distinct changes it undergoes during the key developmental stages that characterize it, from em- bryonic life through to post-menopausal age. In addition, it discusses recent advances in our understanding of the normal function of the breast during lac- tation, with special reference to breastmilk, its composition, and how it can be utilized as a tool to advance knowledge on normal and aberrant breast devel- opment and function. Finally, anatomical and molecular traits associated with aberrant expansion of the breast are discussed to set the basis for future com- parisons that may illuminate the origin of breast cancer. Clin. Anat. Clin. Anat. 00:000–000, 2012. VC 2012 Wiley Periodicals, Inc. Key words: breast; mammary gland; anatomy; histology; stem cells; lactocytes; lactation; breast cancer INTRODUCTION Grant sponsors: Medela AG, Women and Infants Research The mammary gland is an organ unique to the Foundation. class Mammalia, with the specific function to synthe- *Correspondence to: Donna Geddes, Hartmann Human Lactation size, secrete, and deliver milk to the newborn upon Research Group, School of Chemistry and Biochemistry, Faculty of demand for its optimal nourishment, protection, Life and Physical Sciences, The University of Western Australia, 35 and development (Medina, 1996). Milks from differ- Stirling Highway, Crawley, Western Australia 6009, Australia. ent mammalian species vary in composition and are E-mail: [email protected] uniquely appropriate for the species for which the Received 2 July 2012; Accepted 16 August 2012 milk was synthesized. In humans, the life cycle of Published online in Wiley Online Library (wileyonlinelibrary.com). the female mammary gland is epitomized by drastic DOI 10.1002/ca.22165 VC 2012 Wiley Periodicals, Inc. 2 Hassiotou and Geddes changes in composition, architecture, and functional- DEVELOPMENT OF THE BREAST ity, mediated by marked changes in gene expres- sion, that characterize its physiological stages of de- Breast development during life follows a time velopment, all of which are aimed at allowing it to course of distinct phases. Beginning with the forma- perform its function as a milk-producing organ with tion of the mammary crest and subsequent primitive the birth of the infant. The key mammary develop- mammary buds during embryonic life, it continues mental stages include fetal growth, infant (pre- with minimal growth during infancy followed by a pubertal) growth, pubertal expansion, pregnancy- rapid growth phase at puberty in the female. Breast and lactation-associated remodeling, and post-lacta- development culminates during the pregnancy and tional and post-menopausal involution (Russo, 2004; lactation cycle (PLC) when the mammary gland Geddes, 2007). A sound knowledge of the develop- undergoes complete remodeling, maturating into a ment, anatomy, physiology, and regulation of the functional milk-secretory organ. Regression of PLC- breast is integral in the understanding of both the induced growth is initiated as weaning is commenced normal biology and function of this organ and its be- and is completed after involution when the breast nign or malignant pathologies and their successful regresses to a resting state. Remarkably, the PLC- treatment. induced mammary growth and subsequent involution Unlike most other organs of the body, which de- can be repeated at multiple pregnancies during the velop to a relatively mature state during embryonic reproductive life of a female. The cycle is completed life, the mammary gland reaches a mature functional with a further phase of involution post-menopause. state only during the pregnancy-lactation cycle (PLC) Full development of the breast during lactation is in the adult female. Therefore, this is the most im- critical to provide the appropriate volume and com- portant developmental stage of the breast when it is position of breastmilk for the growth, protection, and characterized by a very high metabolic demand, development of the infant. Further, it has been requiring about 25% of daily maternal energy intake shown that the PLC is protective against the develop- during lactation to produce milk (Hartmann, 2007). ment of breast cancer in the long term (Key et al., Human breastmilk has a unique biochemical and cel- 2001), particularly when it occurs before the age of lular composition, providing the infant with optimal 30 and with an interval of less than 14 years nutritional, protective, and developmental factors. between menarche and the first pregnancy. Multi- Due to this, the American Academy of Pediatrics parity confers slightly more protection; however, the (AAP, 2005) and the World Health Organisation effect is not as great as that of the first pregnancy (Russo, 2011). The above strongly suggest that (WHO) recommend breastfeeding (or the provision pregnancy and lactation induce permanent breast of mother’s own milk) for all infants, including high changes through which they exert a protective, risk and premature infants. Despite this, few women, yet still not well understood, effect against breast especially in developed countries, reach current rec- malignancy. ommendations for breastfeeding duration, which state exclusive breastfeeding to six months postpar- tum, with breastfeeding to continue up to two years Fetal Development or beyond. This situation suggests inadequate sup- Embryonic development of the breast is initiated port of the mother-infant dyad (term and preterm) by six weeks of gestation from a thickened ectoder- to achieve and maintain a successful lactation, mal ridge extending from the groin to the axilla on demonstrating a clear need to bridge scientific inves- the anterior surface of the embryo (milk line). The tigation of breast function and development of evi- entire ridge apart from the pectoral region (second dence-based medical treatment. to sixth rib) regresses to form the mammary gland. In addition to pathologies associated with suc- Supernumerary glands may develop at any location cessful lactation, breast cancer is another devastat- along the ectodermal ridge presenting as either ing pathology of the mammary gland, with current mammary glands or accessory nipples in 2–6% of statistics reporting it as the most frequent cancer women (Vorherr, 1974; Schmidt, 1998; Russo, and cancer-related cause of death in women world- 2004). wide (AIHW, 2010). Despite considerable scientific Between week 7 and 8 of gestation (embryo 10–11 effort into elucidating the primary cause of breast mm), the mammary parenchyma invades the stroma cancer, the differing responses to therapy and char- forming an elevated portion termed the mammary acteristics of its various subtypes (Perou et al., crest. A basement membrane separates the invading 2000) together with the lack of basic understanding ectodermal cells from the underlying mesoderm. of the physiology of the breast have hindered the de- Between 10 and 12 weeks gestation (embryo 30–68 velopment of appropriate preventative guidelines mm), mammary epithelial buds form, a phase that and treatment options for these patients. This review marks the commencement of distinct differentiation summarizes the current knowledge of the normal patterns. At this stage, subtle differences can be seen anatomy of the human breast and the distinct between males and females, such as the female ovoid changes it undergoes during the key developmental versus male spherical budding shape, and the female stages that characterize it. In addition, anatomical smaller bud volume. The smooth musculature of the and molecular traits associated with aberrant expan- areola and nipple are formed between 12 and 16 sion of the breast are discussed to set the basis for weeks. The appearance of the mammary buds does future comparisons that may illuminate the origin of not change significantly until weeks 13–20, when a breast cancer. depression is formed at the surface of the buds and A Review of the Anatomy of the Female Breast 3 proliferation of distinct epithelial progenitor popula- Puberty tions results in secondary
Load more

Recommended publications
  • Dr. Hale's Lactation Risk Categories
    Just like during pregnancy, it is extremely important to talk to your doctor, pharmacist or lactation consultant before taking any medications. Most medications are safe, but there are many that can pass through your breastmilk to baby. Your lactation consultant also has access to resources about medication safety and breastfeeding. Medication Category Dr. Hale’s Lactation Risk Categories Acetaminophen (Tylenol) L1 L1 Safest Amoxicillin L1 Drug which has been taken by a large number of breastfeeding moth- ers without any observed increase in adverse effects in the infant. Aspirin L3 Controlled studies in breastfeeding women fail to demonstrate a risk to the infant and the possibility of harm to the breastfeeding infant is Birth Control – ONLY Acceptable remote; or the product is not orally bioavailable in an infant. L2 Safer Norethindrone, Depo-Provera, Drug which has been studied in a limited number of breastfeeding Implanon, Mirena, Plan B women without an increase in adverse effects in the infant; And/or, the evidence of a demonstrated risk which is likely to follow use of this medication in a breastfeeding woman is remote. Cetrizine (Zyrtec) L2 L3 Moderately Safe There are no controlled studies in breastfeeding women, however Dextromethorphan (Robitussin L1 the risk of untoward effects to a breastfed infant is possible; or, con- etc.) trolled studies show only minimal non-threatening adverse effects. Drugs should be given only if the potential benefit justifies the poten- Dimenhydrinate (Dramamine) L2 tial risk to the infant. L4 Possibly Hazardous Diphenhydramine (Benadryl) L2 There is positive evidence of risk to a breastfed infant or to breast- milk production, but the benefits of use in breastfeeding mothers Fluoxetine (Prozac) L2 may be acceptable despite the risk to the infant (e.g.
    [Show full text]
  • Breastfeeding Is Best Booklet
    SOUTH DAKOTA DEPARTMENT OF HEALTH WIC PROGRAM Benefits of Breastfeeding Getting Started Breastfeeding Solutions Collecting and Storing Breast Milk Returning to Work or School Breastfeeding Resources Academy of Breastfeeding Medicine www.bfmed.org American Academy of Pediatrics www2.aap.org/breastfeeding Parenting website through the AAP www.healthychildren.org/English/Pages/default.aspx Breastfeeding programs in other states www.cdc.gov/obesity/downloads/CDC_BFWorkplaceSupport.pdf Business Case for Breastfeeding www.womenshealth.gov/breastfeeding/breastfeeding-home-work- and-public/breastfeeding-and-going-back-work/business-case Centers for Disease Control and Prevention www.cdc.gov/breastfeeding Drugs and Lactation Database (LactMed) www.toxnet.nlm.nih.gov/newtoxnet/lactmed.htm FDA Breastpump Information www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ HomeHealthandConsumer/ConsumerProducts/BreastPumps Healthy SD Breastfeeding-Friendly Business Initiative www.healthysd.gov/breastfeeding International Lactation Consultant Association www.ilca.org/home La Leche League www.lalecheleague.org MyPlate for Pregnancy and Breastfeeding www.choosemyplate.gov/moms-pregnancy-breastfeeding South Dakota WIC Program www.sdwic.org Page 1 Breastfeeding Resources WIC Works Resource System wicworks.fns.usda.gov/breastfeeding World Health Organization www.who.int/nutrition/topics/infantfeeding United States Breastfeeding Committee - www.usbreastfeeding.org U.S. Department of Health and Human Services/ Office of Women’s Health www.womenshealth.gov/breastfeeding
    [Show full text]
  • Download/Rozdzial05.Pdf (Accessed on 1 January 2007)
    cancers Article Early Alcohol Use Initiation, Obesity, Not Breastfeeding, and Residence in a Rural Area as Risk Factors for Breast Cancer: A Case-Control Study Dorota Anna Dydjow-Bendek * and Paweł Zagozd˙ zon˙ Department of Hygiene and Epidemiology, Medical University of Gdansk, 80-211 Gdansk, Poland; [email protected] * Correspondence: [email protected] Simple Summary: Breast cancer became the most common cancer globally in 2021, according to the World Health Organization. The aim of the study was to evaluate risk factors for breast cancer, such as early alcohol use initiation, obesity, breastfeeding, and place of residence. The effect of alcohol consumption by girls has been assessed in only a few studies and is not fully understood. In this study, it has been found to be associated with a higher risk of breast cancer. Our study also shed light on the incidence disparity—women were more at risk in the countryside than in the city. The results of this study should be included in the preparation of breast cancer prevention programs and also aimed at women in adolescence and early adulthood because exposures during childhood and adolescence can affect a woman’s long-term risk of breast cancer. Every effort should also be made to ensure that access to knowledge is open to all, regardless of where they live, giving all women equal opportunities. Citation: Dydjow-Bendek, D.A.; Zagozd˙ zon,˙ P. Early Alcohol Use Abstract: Initiation, Obesity, Not Breastfeeding, The aim of this study was to determine the risk factors for breast cancer in the Polish and Residence in a Rural Area as Risk population.
    [Show full text]
  • Clinical Update and Treatment of Lactation Insufficiency
    Review Article Maternal Health CLINICAL UPDATE AND TREATMENT OF LACTATION INSUFFICIENCY ARSHIYA SULTANA* KHALEEQ UR RAHMAN** MANJULA S MS*** SUMMARY: Lactation is beneficial to mother’s health as well as provides specific nourishments, growth, and development to the baby. Hence, it is a nature’s precious gift for the infant; however, lactation insufficiency is one of the explanations mentioned most often by women throughout the world for the early discontinuation of breast- feeding and/or for the introduction of supplementary bottles. Globally, lactation insufficiency is a public health concern, as the use of breast milk substitutes increases the risk of morbidity and mortality among infants in developing countries, and these supplements are the most common cause of malnutrition. The incidence has been estimated to range from 23% to 63% during the first 4 months after delivery. The present article provides a literary search in English language of incidence, etiopathogensis, pathophysiology, clinical features, diagnosis, and current update on treatment of lactation insufficiency from different sources such as reference books, Medline, Pubmed, other Web sites, etc. Non-breast-fed infant are 14 times more likely to die due to diarrhea, 3 times more likely to die of respiratory infection, and twice as likely to die of other infections than an exclusively breast-fed child. Therefore, lactation insufficiency should be tackled in appropriate manner. Key words : Lactation insufficiency, lactation, galactagogue, breast-feeding INTRODUCTION Breast-feeding is advised becasue human milk is The synonyms of lactation insufficiency are as follows: species-specific nourishment for the baby, produces lactational inadequacy (1), breast milk insufficiency (2), optimum growth and development, and provides substantial lactation failure (3,4), mothers milk insufficiency (MMI) (2), protection from illness.
    [Show full text]
  • Maternal Intake of Cow's Milk During Lactation Is Associated with Lower
    nutrients Article Maternal Intake of Cow’s Milk during Lactation Is Associated with Lower Prevalence of Food Allergy in Offspring Mia Stråvik 1 , Malin Barman 1,2 , Bill Hesselmar 3, Anna Sandin 4, Agnes E. Wold 5 and Ann-Sofie Sandberg 1,* 1 Department of Biology and Biological Engineering, Food and Nutrition Science, Chalmers University of Technology, 412 96 Gothenburg, Sweden; [email protected] (M.S.); [email protected] (M.B.) 2 Institute of Environmental Medicine, Unit of Metals and Health, Karolinska Institutet, 171 77 Stockholm, Sweden 3 Department of Paediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden; [email protected] 4 Department of Clinical Science, Pediatrics, Sunderby Research Unit, Umeå University, 901 87 Umeå, Sweden; [email protected] 5 Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 90 Gothenburg, Sweden; [email protected] * Correspondence: ann-sofi[email protected] Received: 10 November 2020; Accepted: 25 November 2020; Published: 28 November 2020 Abstract: Maternal diet during pregnancy and lactation may affect the propensity of the child to develop an allergy. The aim was to assess and compare the dietary intake of pregnant and lactating women, validate it with biomarkers, and to relate these data to physician-diagnosed allergy in the offspring at 12 months of age. Maternal diet during pregnancy and lactation was assessed by repeated semi-quantitative food frequency questionnaires in a prospective Swedish birth cohort (n = 508). Fatty acid proportions were measured in maternal breast milk and erythrocytes. Allergy was diagnosed at 12 months of age by a pediatrician specialized in allergy.
    [Show full text]
  • Side-Branching in the Mammary Gland: the Progesterone–Wnt Connection
    Downloaded from genesdev.cshlp.org on September 27, 2021 - Published by Cold Spring Harbor Laboratory Press PERSPECTIVE Side-branching in the mammary gland: the progesterone–Wnt connection Gertraud W. Robinson,1 Lothar Hennighausen, and Peter F. Johnson2 Laboratory of Genetics and Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0822 USA; 2Eukaryotic Transcriptional Regulation Section, Regulation of Cell Growth Laboratory, National Cancer Institute-Frederick Cancer Research Development Center (FCRDC), Frederick, Maryland 21702-1201 USA The mammary gland is a derivative of the ectoderm mammary ducts during puberty and pregnancy. Their whose development begins in the embryo and progresses studies demonstrate that a nuclear signal is converted after birth. The major part of development occurs in the into a secreted signal that can control the fate of adjacent adolescent and adult animal. Hormones produced by the cells in a paracrine fashion. A genetic understanding of pituitary, the ovaries, the uterus, the placenta, and the this and other signaling pathways regulating cell growth mammary gland itself control this process. Over the past in the mammary gland will improve our ability to ma- century, surgical, biological, and genetic tools have been nipulate these processes and thus design strategies for used to gain insight into physiological and pathological prevention and treatment of breast cancer. processes in the mammary gland. Originally, endocrine ablation and reconstitution experiments provided a de- scriptive framework of the role of ovarian and pituitary Tools to investigate signaling pathways hormones (Halban 1900; Nandi 1958). These experi- Several features of the mammary gland provide unique ments demonstrated a clear requirement for the ovarian opportunities for experimental manipulations to inte- steroids estrogen and progesterone for ductal growth and grate systemic, local and cell-specific signaling path- alveolar development (Topper and Freeman 1980).
    [Show full text]
  • Breastfeeding Support Credentials
    Who’s Who? A glance at breastfeeding support in the United States Lactation support is often needed to help mothers initiate and continue breastfeeding. There are many kinds of help available for breastfeeding mothers including peer counselors, certified breastfeeding educators and counselors, and lactation professionals such as the International Board Certified Lactation Consultant (IBCLC®). Breastfeeding support is valuable for a variety of reasons, from encouragement and emotional support to guidance and assistance with complex clinical situations. Mothers benefit from all kinds of support, and it is important to receive the right kind at the right time. The breastfeeding support categories listed below each play a vital role in providing care to mothers and babies. Breastfeeding Support Prerequisites Training Required Scope of Practice Type • 90 hours of lactation-specific education Recognized health Provide professional, • College level health science professional or evidence based, clinical courses Professional satisfactory completion lactation management; • 300-1000 clinical practice hours (International Board Certified of collegiate level educate families, health Lactation Consultant, IBCLC®) • Successful completion of a health sciences professionals and others criterion-referenced exam offered coursework. about human lactation. by an independent international board of examiners. Certified • 20-120 hours of classroom training Provide education and • Often includes a written exam guidance for families (i.e. Certified Lactation N/A Counselor, Certified or “certification” offered by the on basic breastfeeding Breastfeeding Educator, etc. ) training organization issues. Provide breastfeeding information, Peer Personal breastfeeding • 18-50 hours of classroom training encouragement, and (i.e. La Leche League, WIC experience. Peer Counselor, etc.) support to those in their community. Copyright © 2016 by USLCA.
    [Show full text]
  • MATERNAL & CHILD HEALTH Technical Information Bulletin
    A Review of the Medical Benefits and Contraindications to Breastfeeding in the United States Ruth A. Lawrence, M.D. Technical Information Bulletin Technical MATERNAL & CHILD HEALTH MATERNAL October 1997 Cite as Lawrence RA. 1997. A Review of the Medical Benefits and Contraindications to Breastfeeding in the United States (Maternal and Child Health Technical Information Bulletin). Arlington, VA: National Center for Education in Maternal and Child Health. A Review of the Medical Benefits and Contraindications to Breastfeeding in the United States (Maternal and Child Health Technical Information Bulletin) is not copyrighted with the exception of tables 1–6. Readers are free to duplicate and use all or part of the information contained in this publi- cation except for tables 1–6 as noted above. Please contact the publishers listed in the tables’ source lines for permission to reprint. In accordance with accepted publishing standards, the National Center for Education in Maternal and Child Health (NCEMCH) requests acknowledg- ment, in print, of any information reproduced in another publication. The mission of the National Center for Education in Maternal and Child Health is to promote and improve the health, education, and well-being of children and families by leading a nation- al effort to collect, develop, and disseminate information and educational materials on maternal and child health, and by collaborating with public agencies, voluntary and professional organi- zations, research and training programs, policy centers, and others to advance knowledge in programs, service delivery, and policy development. Established in 1982 at Georgetown University, NCEMCH is part of the Georgetown Public Policy Institute. NCEMCH is funded primarily by the U.S.
    [Show full text]
  • Estrogen and Progesterone Treatment Mimicking Pregnancy for Protection from Breast Cancer
    in vivo 22 : 191-202 (2008) Review Estrogen and Progesterone Treatment Mimicking Pregnancy for Protection from Breast Cancer AIRO TSUBURA, NORIHISA UEHARA, YOICHIRO MATSUOKA, KATSUHIKO YOSHIZAWA and TAKASHI YURI Department of Pathology II, Kansai Medical University, Moriguchi, Osaka 570-8506, Japan Abstract. Early age at full-term pregnancy lowers the risk of The etiology of human breast cancer is largely unknown. breast cancer in women; lactation seems to be of marginal Genetic susceptibility, hormonal effects and environmental importance and aborted pregnancy is not associated with factors appear to be major determinants. However, known reduced risk. Although early full-term pregnancy provides genetic risk factors are present in only 10% to 15% of breast protection against breast cancer, first full-term pregnancy in cancer cases (1). Many aspects of hormonal effects confer older women appears to increase the risk. The protective effect increased risk of human breast cancer. The incidence of human of pregnancy has also been observed in rats and mice; in these breast cancer is 100-fold greater for females than for males and animals, lactation has an additive effect and interrupted female reproductive history is a consistent risk factor for pregnancy provides partial but significant protection. human breast cancer (2, 3). Studies indicate that early Pregnancy at a young age ( 3 months) is highly effective, but menarche and late menopause, both of which increase the ≤ pregnancy in older animals ( 4 months) is less effective. duration of ovarian steroid exposure, positively correlate with ≥ Parity-induced protection against mammary cancer in rodents increased risk; bilateral oophorectomy at an early age is can be reproduced by short-term treatment (approximately associated with reduced risk (4).
    [Show full text]
  • Substance Use in Pregnancy
    MAY 2017 SUBSTANCE USE IN PREGNANCY Prepared By: Aaron Fields, MD University of Rochester Medical Center, NYS Maternal & Infant Health Center of Excellence 265 Crittenden Blvd, Rochester, NY 14642 – Tel: 585-276-7893 – Fax: 585-461-4532 [email protected] – www.mihcoe.org Introduction ..............................................................................................................................................................2 What is Addiction? .....................................................................................................................................................3 Drugs of Abuse ..........................................................................................................................................................4 Opioids ................................................................................................................................................................................ 4 Stimulants ........................................................................................................................................................................... 4 Nicotine............................................................................................................................................................................... 5 Alcohol ................................................................................................................................................................................ 6 Marijuana ...........................................................................................................................................................................
    [Show full text]
  • What Makes a Mammal a Mammal?
    GRADE LEVELS: 3 - 4 CORRELATION TO NEXT GENERATION SCIENCE STANDARDS: 3-LS4-3, 4-LS1-1 TEACHER’S SKILLS/PROCESSES: observation, analysis, comparison & generalization, identification, creativity OBJECTIVE: Students will be able to identify the five charac - teristics by which mammals are determined. GUIDE UNIT ONE LESSON ONE What Makes a Mammal a Mammal? BACKGROUND Classifying animals into categories and groups based on their similarities and differences is the first step in studying and understanding their WHITE-TAILED DEER origins, development and interdependence. Mammals have the following characteristics: 1. They are covered with hair or fur. 2. They are warm-blooded (mean - ing their internal body temperature is maintained at a constant level regardless of external conditions). 3. They are usually born alive and relatively well-devel - oped, having grown inside the mother’s body in a special organ called a uterus . The time spent developing in the uterus before birth is called the gestation period and varies in length from species to species (from about 13 days in the Virginia opossum to 210 days in the white-tailed deer). 4. After birth the young are fed with milk that is pro - duced by mammary glands . 5. They have larger and more complex brains than any other group of animals. Focusing on these five characteristics will enhance the students’ awareness of and interest in mammals of Illinois. It will also provide a frame of reference for exploring the similarities and differences among members of the animal kingdom and how those characteristics relate to the environment and lifestyle of individual species. 1 Wild Mammals of Illinois, Illinois Department of Natural Resources PROCEDURE AND DISCUSSION Review the student information with the class, providing students VOCABULARY with (or inviting them to provide) examples of each of the five mam- gestation period—the length of mal characteristics.
    [Show full text]
  • The Milk Supply Equation
    The Making of a Milk Factory Objectives . List the major factors necessary for good milk production . Describe the role of the placenta in mammary gland development during pregnancy. Explain two ways that environmental The Making of a Milk Factory contaminants may interfere with reproductive hormones © 2019 Lisa Marasco MA, IBCLC, FILCA Hormones and Receptors The Milk Supply Equation SUFFICIENT GLANDULAR TISSUE + INTACT NERVE PATHWAYS & DUCTS + ADEQUATE HORMONES & RECEPTORS + ADEQUATE LACTATION-CRITICAL NUTRIENTS + ADEQUATE & EFFECTIVE MILK REMOVAL (Good management, effective baby) = GOOD MILK SUPPLY Directors of the process Important players by stage Hormones important to milk production Puberty Pregnancy Lactation Insulin Estrogen Estrogen Cortisol Lactogenic Progesterone Progesterone Complex HPL Prolactin Chorionic Gonadotropin Maintains metabolism; Growth Hormone Growth Hormone Thyroxine - Supports & directs IGF-1 IGF-1 PTPRF pituitary Prolactin Prolactin Insulin Insulin Regulate mammary blood Cortisol Cortisol PTHrP - flow; calcium transport and Thyroxine Thyroxine homeostasis PTHrP PTHrP Oxytocin Oxytocin - milk delivery With permission: Andaluz Waterbirth Center © Lisa Marasco 2019 1 The Making of a Milk Factory Hormone receptors 101 Hormone Receptors 201 Hormones- travel thru blood or synthesized locally Dynamic: Expressed by genes ER α, β Expressed PR α, β R Up & down regulation where and PRLR L, S Can be resistant as needed OTR H Can be hypersensitive Can be influenced positively or negatively by other hormones Receptors: Integral to hormone function, located on “target tissues,” on or in cells Can be influenced by environment The Big Construction Picture PR-A Phase I ER PR-B ERα Series of stages of organo-genesis lasting until ERβ PRLrL adulthood that are irreversible (fetal through puberty) PR-B Phase II Series of changes involving growth and secretory differentiation of the lobulo-alveolar system that are reversible Estrogen Prolactin Progesterone (Preg, lactation, involution) Horseman, N.
    [Show full text]