Exam1
Chapter 1: Introduction to Animal Reproduction
In what ways does reproductive science impact food production systems?
Reproductive science is important in maintaining food herd sizes, and producing offspring with desirable characteristics.
Who was the first scientist to describe the fallopian tubes, and why is this discovery significant?
Gabriele Falloppio first described fallopian tubes. Explains how eggs travel from ovaries to uterus
What does the phrase “Ex ovo omnia” mean, who coined it, and how does it relate to the field of reproduction?
“ex ovo omnia” means all life from eggs. Coined by William Harvey. He linked reproduction with egg formation.
How did Regnier de Graaf’s experiments with female rabbits advance our understanding of ovulation and embryo development?
Graaf discovered that the number of “scar-like” wounds on the ovarian surface corresponded to the number of embryos in the uterus.
What are some modern applications of reproductive science in agriculture?
We can use hormonal regulation, artificial insemination, embryo transfer, and genetic manipulation to increase fertility rates and offspring success in animals.
How has the advent of artificial insemination transformed livestock breeding programs?
Humans can control when a female is inseminated, increasing successful fertility rates. The farmer also does not have to own any male animals.
In what ways can reproductive technologies support the conservation of endangered species?
AI is one of the major technologies used for animal conservation. Facilities involved in conservation efforts can outsource their sperm through AI to preserve genetic diversity. Cloning and IVF are also used.
Chapter 2: Organization & Function of the Female Reproductive System
Identify the major anatomical structures of the female reproductive system and describe their primary functions.
Ovaries: hold and grow follicles/eggs
Oviducts/fallopian tubes: transport egg to uterus
Uterus: stores and grow embryo
Cervix: allows for fluid transfer in/out of uterus, aids in birth
Vagina: birth canal
How does the rectogenital pouch facilitate reproductive examinations in large animals?
The rectogenital pouch allows for manual palpation and ultrasound examination. Can be used to diagnose ovarian status, diagnose pregnancy, assist in AI, and identify reproductive tract abnormalities.
What are the four concentric layers of the female reproductive tract, and what roles does each layer play?
Seros: outer layer, covers and protects surface of reproductive tract
Muscularis: two layers of smooth muscle (outer longitudinal and inner circular), provides contractability for embryo transport and parturition
Submucosa:
Mucosa: inner layer, lines the lumen, secretes mucus and fluids, protects vagina during copulation
Describe the structure and supportive function of the broad ligament in relation to the reproductive organs.
Connective tissue sheet that suspends and supports the ovaries, uterus, oviducts, and vagina. Houses vascular supply, lymphatic drainage, and nerves of reproductive tract
What are the key differences in ovarian structure between mares and other species?
Ovulation occurs at Ovulation Fossa, not randomly. CLs are embedded within ovarian tissue and do not protrude. Cortex is inside and medulla is outside.
Which hormones are secreted by the corpus luteum, and what roles do they play in reproductive physiology?
Progesterone: cycle regulation
Oxytocin: aids in uterine contractions
Relaxin: prepares reproductive tract for parturition
Inhibin and actin: regulate follicular development
What are the different types of ovarian follicles, and how do they develop during the follicular phase?
Primordial follicles: most immature, smallest, located in cortex
Primary follicles: slightly more advanced
Secondary follicles: two or more layers of granulosa cells
Tertiary follicles: fluid-filled cavity called antrum
Where does fertilization typically occur within the female reproductive tract, and why is this location critical?
Typically occurs in ampulla. Ampulla secretions create optimal environment for fertilization
Explain how the cervix functions as a barrier during both pregnancy and estrus.
Facilitates sperm passage and birth, protects uterus
In what ways does the vaginal epithelium change throughout the estrous cycle?
Estrogen thickens the vaginal epithelium during estrus, mechanical barrier against pathogens and mechanical injury during copulation
What is the function of the vestibule within the female reproductive system?
Region shared by urinary and genital systems
How does the clitoris contribute to female reproductive behavior?
Supplied with sensory nerve endings
What role do uterine glands play in maintaining pregnancy?
Beneficial secretions for embryo survival and development, regulated by progesterone
Chapter 3: Organization & Function of the Male Reproductive System
What are the primary anatomical components of the male reproductive system?
Spermatic cord: houses blood vessels, nerves, and vas deferens
Testes: produce sperm and testosterone
Epididymis: provides environment for sperm maturation and storage
Penis: copulatory organ for sperm delivery
Accessory sex glands: produces seminal plasma that facilitates sperm transport
Describe the role of the epididymis in sperm maturation and storage.
Head and body is where sperm starts to mature. Tail acts as storage and shipping center, holds sperm for ejaculation
How do the accessory sex glands contribute to the composition of seminal plasma?
It has different properties depending on the species
What functions does the prostate gland serve in male reproduction?
Secretes a fluid that helps transport and nourish semen during ejaculation
Explain how the bulbourethral gland contributes to the ejaculate.
Provides lubrication
How does testosterone regulate the function of accessory sex glands?
Important in maintaining thermoregulation and proper secretions
Identify the three main parts of the penis and describe their roles in reproduction.
The root: base of penis attached to ischium of pelvis
The shaft: main body
The glans penis: distal end of penis, specialized for sensory input, primary trigger for ejaculation
What is the function of the corpus cavernosum in achieving penile erection?
Becomes enlarged with blood during erection causing increased rigidity and strength
How does the corpus spongiosum provide structural support to the penis?
Surrounds urethra, ensuring it stay open during erection and ejaculation
What role does the retractor penis muscle play in penile retraction?
Hold penis retracted inside preputial sheath when contracted. Allows penis to protrude when relaxed
How does the ischiocavernosus muscle facilitate penile erection?
Compress the cura to retain blood within the penis during erection
Describe the function of the urethralis muscle during ejaculation.
Expels semen and seminal plasma with its contractions
How does the bulbospongiosus muscle assist in the expulsion of semen?
Expels semen with its contractions
How do variations in penile morphology among species reflect adaptations for reproductive success?
In cats, ovulation occurs after copulation, so male cats have penile spines to help stimulate the female cat to ovulate.
Male boars have corkscrew shaped glans to penetrate female cervix during copulation
What role does the tunica albuginea play in maintaining penile structure and function?
Connective tissue layer that contains vascularization for the testes
How do androgens such as testosterone influence the size and function of accessory sex glands?
Testosterone is used for thermoregulation of testes. Accessory sex glands shrink in size and reduce secretions in the absence of androgens.
Chapter 4: Embryogenesis of the Pituitary Gland & Reproductive Tract Development
What are the three primary germ layers, and which organs or tissues do they form during embryogenesis?
Endoderm: innermost layer à digestive tract, liver, pancreas, lungs, endocrine organs
Mesoderm: middle layer à circulatory system, skeleton, muscles, urinary system, most of reproductive system
Ectoderm: outer layer à central nervous system,, sensory organs, skin, glands, hair, hoods
What is Rathke's pouch, and what part of the pituitary does it form?
Forms anterior pituitary
Explain the role of the infundibulum in the development of the pituitary gland.
Forms posterior pituitary
How does the SRY gene influence male sexual differentiation?
SRY gene is only found on Y chromosome, triggers testis development. In it’s absence, gonads develop into ovaries
Compare the development of the mesonephric (Wolffian) ducts and the paramesonephric (Müllerian) ducts in males and females.
Wolffian ducts develop male reproductive system, mullerian ducts develop female reproductive system
What is cryptorchidism, and how does it affect male fertility?
Cryptorchidism is when the testicles stay in the abdominal canal and do not descend. Reduces male fertility
How does female reproductive development proceed in the absence of the SRY protein?
Gonads develop into ovaries
What role does Müllerian Inhibiting Substance (MIS) play in male reproductive development?
Inhibit male gonad development
Chapter 5: Regulation of Reproduction—Nerves, Hormones, & Target Tissues
What are the two primary neural pathways that regulate reproduction, and how do they differ?
Nervous system: detects stimuli
Endocrine system: hormone regulation
Describe the Simple Neural Reflex in reproduction, providing two specific examples.
Simple neural reflexes are fast and direct, and is responsible for ejaculation and temperature regulation of testes
How does the Neuroendocrine Reflex differ from the Simple Neural Reflex, and what is one example of its role in reproduction?
Neuroendocrine involves hormones and is responsible for suckling reflex and milk ejection
Explain the significance of the Hypothalamo-Hypophyseal Portal System in hormonal regulation.
Allows hypothalamus to directly transport hormones to anterior pituitary
What roles do key gonadal hormones (estrogen, progesterone, testosterone) play in reproduction?
They regulate reproductive functions
Categorize hormones by their mode of action and provide an example for each category.
Tropic hormones: secreted by anterior pituitary, act on endocrine glands to stimulate hormone production (FSH, LH)
Sex steroid hormones: secreted by gonads to regulate reproductive functions (estrogen, progesterone, testosterone)
Chapter 6: Puberty
What role does estradiol play in brain feminization during prenatal development?
Defeminizes the brain. In males, testosterone is converted to estradiol in the brain à eliminates GnRH surge center. In females, estradiol cannot enter the brain à GnRH surge center remains functional.
How does testosterone influence male brain development in relation to feminization?
Testosterone regulates GnRH release
What is the function of alpha-fetoprotein in preventing estradiol from affecting the female brain?
In females, estradiol cannot enter the brain à GnRH surge center remains functional.
Why is castration at birth significant for GnRH secretion and subsequent reproductive development in males?
Males castrated at birth retain some ability to secrete GnRH surges similar to females
How is puberty defined in females, and what observable changes signal its onset?
Ability to successfully reproduce. Females will exhibit sexual receptivity and estrus behaviors
What biological milestone marks the first ovulation in females, and why is it important?
Ability to support pregnancy
How is the ability to support pregnancy used as a criterion for defining puberty in females?
Indicates reproductive system is fully mature and capable of sustaining gestation
How does the onset of reproductive behavior signal puberty in males?
Signals full reproductive capability
What role does the presence and quantity of sperm in the ejaculate play in determining male fertility during puberty?
Males must produce adequate sperm quantity and quality for successful fertilization
How do GnRH neurons contribute to the initiation of puberty?
GnRH slowly builds up in the body until it reaches threshold and triggers puberty onset
Describe the 'Dimmer Switch' model for the gradual increase in GnRH secretion leading to puberty.
GnRH slowly builds up in the body until it reaches threshold and triggers puberty onset
What differences exist between the tonic and surge centers of GnRH release in males and females, and how do these differences affect puberty onset?
Tonic center controls baseline pulsatile secretion. Surge center is responsible for preovulatory GnRH surges in females
How do negative and positive feedback mechanisms regulate GnRH secretion during puberty?
In males, GnRH is steady and regulated by testosterone. In females, GnRH pulses until estradiol reaches threshold, then releases massive GnRH amount
In what ways does the male feedback mechanism for GnRH differ from that in females?
In males, GnRH is steady and regulated by testosterone. In females, GnRH pulses until estradiol reaches threshold, then releases massive GnRH amount
What are the key physiological and behavioral events that signal the onset of puberty in both sexes?
Females: first heat, sexual receptivity
Males: first ejaculation, mounting behavior
How do metabolic factors, such as glucose and fatty acid metabolism, influence puberty onset in females?
Females must reach adequate size/have enough fat for puberty onset
How do environmental factors, such as the season of birth, impact the timing of puberty in females?
Spring born lambs reach puberty by autumn. Autumn born lambs reach puberty the following summer. Queens born in spring reach puberty the following spring. Queens born in summer experience delayed puberty. Puberty is regulated by daylight exposure.
In what ways do social factors (e.g., group dynamics, presence of males) affect the onset of puberty in females?
Presence of males accelerates puberty in some species. Larger group sizes may promote earlier puberty, while smaller group sizes can delay puberty.
Chapter 7: Reproductive Cyclicity—Terminology & Basic Concepts
How do the terms "estrus" and "estrous" differ in meaning and usage?
Estrus: refers to the period of sexual receptivity in females, heat
Estrous: describes conditions or cycles related to estrus
What is the origin and definition of the term "estrus"?
Derived from Greek word meaning “gadfly, sting, or frenzy”. Inspired by agitation seen in females during estrus
How do seasonal and non-seasonal reproductive patterns differ among animals?
Seasonally reproductive animals are only able to reproduce during specific seasons, short days or long days. Non-seasonally reproductive animals either cycle once annually, or multiple times throughout the year
How do gonadotropin-releasing hormones (GnRH) influence the reproductive system?
Plays a role in puberty. Elevated GnRH levels stimulates the release of FSH and LH
What distinguishes monoestrous species from polyestrous species?
Monoestrous species have one reproductive cycle per year, while polyestrous species have multiple cycles throughout the year
What mechanisms drive photoperiodic responses in both long-day and short-day breeders?
Long-day breeders: light triggers specific neurons in hypothalamus, which stimulate GnRH, FSH and LH secretion, leading to ovulation
Short-day breeders: increase in melatonin reduces GnRH secretion, suppressing ovulation
How is the menstrual cycle defined, and in what ways does it differ from the estrous cycle?
During the menstrual cycle, the endometrial uterine lining is shed, which does not occur during estrous.
What are the primary phases of the menstrual cycle, and what roles do estrogen and progesterone play in each?
Follicular phase and luteal phase. Estrogen increases during follicular phase, and progesterone increases during the luteal phase
What is menopause, and what factors contribute to its onset?
Menopause is the end of cyclicity in women, occurs due to depletion of egg reserves and lower levels of estrogen and progesterone
How does lactational amenorrhea occur, and what impact does it have on reproductive health?
High levels of prolactin during lactation inhibit ovulation
In what ways do nutritional factors influence female reproductive health?
Nutrition impacts lactational anestrus
What global variations exist in menstrual cycles, and what factors contribute to these differences?
Nutrition significantly impacts menstrual cycle. Cultures with different dietary practices and physical activity levels may display different menstrual patterns
How does lactation function as a contraceptive, and what is the underlying mechanism?
High levels of prolactin during lactation inhibit ovulation