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Exam 4 Review
Reproductive and Mammary Systems
AN S 214 Supplemental Instruction
4/24/13
Reproductive System Outline
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Male Anatomy
Heat Regulation of Testes
Hypothalamic-Pituitary-Gonadal Axis
Spermatogenesis and Spermiogenesis
Female Anatomy
Ovarian Cycle
Uterine (Menstrual) Cycle
Hypothalamic-Pituitary-Gonadal Axis
Putting it All Together
Fertilization and Development
Pregnancy
Duct Formation
Abnormalities
Estrous Cycle
Seasonally Polyestrous
Male Anatomy
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Seminiferous Tubules
Tubulus Rectus
Rete Testis
Efferent Ductules
Epididymis (Head, Body, Tail)
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Seminal Vesicle
– Viscous alkaline seminal fluid
– Fructose, ascorbic acid, coagulating
enzyme, and prostaglandins
– 70% of the volume of semen
Ejaculatory Duct
Prostate
– Milky, slightly acid fluid
– Contains citrate and enzymes
Bulbourethral (Cowper's) gland
– Prior to ejaculation-thick, clear
mucus
– Lubricates the glans penis
– Neutralizes traces of acidic urine
in the urethra
Urethra
Glans Penis
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Seminal fluid + Sperm = Semen
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Heat Regulation of Testes
• Keeps testes 3 degrees Celsius cooler than body
temperature
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– Countercurrent heat exchanger
• Cools arterial blood, warm venous blood
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– Smooth muscle that wrinkles scrotal skin
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– Skeletal muscle that raises or lowers testes
Hypothalamic-Pituitary-Gonadal Axis
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Leydig/Interstitial Cells
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Stimulated by LH
Secrete androgens
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Testosterone
Sertoli/Sustenacular Cells
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Stimulated by FSH
Nourishment of developing spermatozoa
Form blood-testes barrier
Produce inhibin-represses FSH
Secrete androgen-binding protein (ABP)
Produce mullerian duct-inhibiting substance
(MIS)
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Exogenous testosterone
Negative feedback on pituitary
Results in infertility, testicular atrophy and
impotence
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Spermatogenesis and Spermiogenesis
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Spermatogonium-Most primitive cell
– Mitosis
Spermatogonium A
– Mitosis
Spermatogonium B
– Mitosis
Primary Spermatocytes
– Meiosis I
Secondary Spermatocytes
– Meiosis II
Spermatids
Spermatogenesis
Differentiation
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Spermatozoa
– Mature Sperm
Spermiogenesis
Female Anatomy
• Path of Oocyte
– Ovary
– Oviduct
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– Uterus
– Cervix
– Vagina
• External Genitalia
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Clitoris
Labia minora
Labia majora
Accessory glands
Ovarian Cycle
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Follicular Phase
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Primordial Follicle
Primary Follicle
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Secondary Follicle
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Meiosis occurs
Large antrum
Ovulation
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Three layers of cells-One being granulosa cells,
Two of thecal cells
Antrum begins to form
Dominant Follicle, Mature Follicle, Graffian
Follicle, or Vesicular Follicle
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Two layers of granulosa cells
Tertiary Follicle, Late Secondary Follicle, or
Antral Follicle
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One layer of granulosa cells
Secondary oocyte expelled
Luteal Phase
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“Bloody Body”
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“Yellow Body”
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“White Body”
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Uterine (Menstrual) Cycle
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– Days 1-5
– Menstrual flow due to low
hormone levels
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– Days 6-14
– Estrogen levels prompt new
endometrium in uterus
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– Days 15-28
– Progesterone levels prompt
further development of
endometrium
– Glandular secretions
Hypothalamic-Pituitary-Gonadal Axis
• FSH stimulates Granulosa
(G) cells to produce
Estrogens
• LH stimulates Thecal (T)
cells to produce androgens
• Estrogen Production
– Cholesterol  Progesterone
(G&T)  Testosterone (T) –
Aromatase (G)Estradiol (G)
Putting it All Together
Fertilization and Development
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Aided by surface hyaluronidase enzymes, a sperm weaves its
way past granulosa cells of the corona radiata
Binding of the sperm to ZP3 molecules in the zona pellucida
causes rise in calcium levels within the sperm, triggering the
acrosomal reaction
Acrosomal enzymes digest holes through the zona pellucida
clearing a path to the oocyte membrane
The sperm forms an acrosomal process, which binds to the
oocyte’s sperm-binding receptors
The sperm and oocyte plasma membranes fuse, allowing
sperm contents to enter the oocyte
Entry of sperm contents causes a rise in the calcium levels in
the oocyte’s cytoplasm, triggering the cortical reaction. The
result is hardening of the zona pellucida and clipping off of
sperm receptors (slow block to polyspermy)
After the sperm penetrates the secondary oocyte, oocyte
completes meiosis II forming ovum and second polar body
Sperm and ovum nuclei swell, forming pronuclei
Pronuclei approach each other and mitotic spindle forms
between them
Chromosomes of pronuclei intermix. Fertilization is
accomplished (Zygote is formed). Then the DNA replicates in
preparation for the first cleavage stage.
4 cell stage
Morula
Blastocyst
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Implants roughly 7 days after ovulation
Pregnancy
• Hormones
– Estrogen produced by corpus luteum and placenta
• Causes uterine, mammary duct, and breast enlargement
– Progesterone produced by corpus luteum and placenta
• Prevents menstruation, thickens endometrium and breast development
• Maternal recognition of pregnancy produced by blastocyst
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Human- Human Chorionic Gonadotropin
Sow- Estrogen
Mare- Small Unknown Peptide
Cow- Bovine Interferon tau
Ewe- Ovine Interferon tau
• Organ development in utero
– ~8 week cutoff for major malformations
Duct Formation
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– Sex-determining region on Y (SRY
gene)
– Male
– Testosterone promotes
development
– Mullerian inhibiting substance
(MIS) regresses mullerian ducts
• Can cause freemartin in female twin
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– Female
– Absence of testosterone, wolffian
ducts regress
– Absence of MIS, mullerian ducts
develop
Abnormalities
• Male Pseudohermaphrodite
– Genotype: XY
– Phenotype: Testes inside body, female external
genitalia
– Caused by: Androgen Insensitivity Syndrome (AIS)
• Female Pseudohermaphrodite
– Genotype: XX
– Phenotype: Have ovaries, male external genitalia
– Caused by: Congenital Adrenal Hyperplasia
• Adrenal glands overproduce testosterone
Estrous Cycle
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Days in Cycle
Stage of Cycle
Phase
Ovarian Structure
Hormone Pattern
17-20
Proestrus
Follicular
Growing follicles
Corpus albicans
↑Estrogen
↓Progesterone
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Estrus
Follicular
Graffian follicle,
Dominant follicle,
Mature follicle, or
Vesicular follicle
Max. Estrogen
Min. Progesterone
2-4
Metestrus
Luteal
Corpus
hemorrhagicum
↓Estrogen
↑Progesterone
5-16
Diestrus
Luteal
Corpus luteum
Min. Estrogen
Max Progesterone
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Without cyclicity
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Produced by endometrium when no pregnancy occurs
Regress Corpus luteum
Controls when the animal will cycle
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Seasonally Polyestrous
• Goal
– Give birth in spring when food is abundant
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Sheep
5 month gestation
Breed in the fall
↓Light  ↑Melatonin  ↑GnRH  Cyclicity
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Horse
11 month gestation
Breed in the spring
↑Light  ↓Melatonin  ↑GnRH  Cyclicity
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Mammary System Outline
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Alveolus
Lactation Phases
Milk Synthesis and Letdown
Milk Components
Alveolus
• Smallest unit of mammary
• Composed of epithelial cells
– Produce milk components
– Polar in nature
• Nucleus located near basal
membrane
• Golgi apparatus near lumen of
alveolus
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• Many alveoli make a lobule,
many lobules make a lobe
Lactation Phases
Phase of lactation
Mammogenesis
Lactogenesis
Galactokinesis
Galactopoiesis
What is occurring…
Preparation of breasts
Important hormones
Other details…
Duct Growth: E2, GH, GC Breast development
begins in utero
Lobuloalveolar Growth:
E2, GH, GC, P4, PRL
Synthesis and secretion PRL
PRL causes synthesis of
of milk components
milk components in
epithelial cells
Milk ejection
Oxytocin
Oxytocin causes
contraction of
myoepithelial cells
Maintenance of lactation PRL
PRL surge with suckling
PRL inhibits GnRH
rBST (GH) can sustain
lactation
Milk Synthesis and Letdown
Negative
Milk Components
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Water
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– Least variable milk component
– Mainly lactose
– Lactose intolerance is when people lack lactase
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– Most variable milk component
– Mainly Triglycerides
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– Between carbohydrates and fats for variability
– Whey (20%)
– Casein (80%)
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Precipitates from whey at pH 4.6 by chymosin or rennin
Vitamins and Minerals
Immunity
Growth Factors