Reproduction Flashcards
What is Fertilization?
Occurs when the spermatozoon penetrates the cytoplasm of the ovum
What is Meiosis?
- unique process of cell division that produces spermatozoon and ova
- reduction division of reproductive cells so that a chromosome number goes from a diploid to a haploid
What is a Chromosome?
- coiled masses of DNA in nuclei of cells
- genetic blueprint for all structures and functions of an animal
What is a Diploid Chromosome?
- 2n
- 2:indicates number is doubled
- n: number of chromosomes
- always an even pair!
What are Sex Chromosomes?
- designated as either X or Y
- determine the gender of the animal
(XX) chromosomes
-genetically female
(XY) chromosomes
-genetically male
Why is it not possible for there to be an YY combination?
-all males produce XY and and females only produce XX
How can a full diploid be expressed?
- 2n,XX
- 2n,XY
What is a Haploid Chromosome Number?
- haploid is 1/2 of the diploid number
- abbreviated as:
- n,X
- n,Y
- depending on sex chromosome present
- ensures that fertilized ovum (from union of spermatozoa and ova) has diploid number
- number in reproductive cells results from meiosis
What is Reduction Division?
-total number of chromosomes in each daughter cell is reduced to half the number of parent cells
What is Mitosis?
- chromosomes duplicate themselves and then pull apart into 2 daughter cells (preserves diploid number)
- ensures that genetic info stays the same throughout all the body’s cells
What Is Meiosis?
- don’t produce copy before daughter cells are pulled apart
- half of total chromosomes go to each daughter cells
- makes process entirely random, resulting in unique offspring
What is Spermatogenesis?
- production of male sex cells
- occurs in seminiferous tubules of testes
- produces continuously and in very large numbers
What is the first stage of Spermatogenesis?
- begins with cell called primary spermatocyte
- primary spermatocyte has normal diploid number
What is the 2nd stage of Spermatogenesis?
- divides by meiosis into 2 secondary Spermatogenesis
- now are haploid in number and are pushed into tubule lumen
What is the 3rd stage of Spermatogenesis?
- 2nd spermatocyte divide by mitosis into 4 spermatids
- 2 will have X markers and 2 will have Y markers
- now located near center of tubular lumen
- doesn’t go thru anymore cell division, but will grow tails and convert into spermatozoa
- once mature, detach and transport to epididymis for storage b4 ejaculation
What is Oogenesis?
- production of female sex cells
- occurs in ovarian follicles
What is an Ova?
- female sex cells
- produced in the follicles of the ovaries through process known as oogenesis
What are the functions of the Male Reproductive System?
- produce spermatozoa
- deliver spermatozoa to female repro system
- produce male sex hormones
What are the Testes?
- site of spermatogenessis (seminiferous tubules) and testosterone (interstitial cells) production
- located outside abdomen in inguinal region
- housed in scrotum
What are the 3 Structures that make up the Spermatozoa?
- head
- midpiece
- tail
What is the Head of the Spermatozoa?
- contains nucleus of cell
- covered by acrosome
- contains digestive enzymes that help penetrate egg
What is the Midpiece of the Spermatozoa?
-large concentration of mitochondria arranged in spiral pattern
What is the Tail of the Spermatozoa?
- contains muscle like contractile fibrils
- produces whiplike tail movement to propel forward
What is the Gubernaculum?
-band of connective tissue that attaches testes to scrotum
What are Inguinal Rings?
-openings in abdominal muscles thru which testes descend
What is the Scrotum?
- sac of skin that houses testes
- helps regulate temp of testes
- cremaster muscle attaches to scrotum
What is the Spermatic Cord?
- links the testes with the rest of the body
- contains blood vessels, nerves, lymphatic vessels, and vas deferens
- only one artery (testicular artery) carries blood down to testes
- artery is surrounded by pampiniform plexus network of veins
What is the Vagina Tunics?
- connective tissue that forms sheath like layers around testes and spermatic cord
- has 3 layers
What are the layers of the Vagina Tunics?
- Visceral
- parietal
What is the Visceral Vaginal Tunic?
-thin inner layer
What is the Parietal Vaginal Tunic?
-thick, outer layer
What is the Tunica Albuginea?
- fibrous connective tissue capsule surrounding each testes beneath tunics
- septa divdes each testes into lobules that contain seminiferous tubules
What are Seminiferous Tubules?
- site of spermatogenesis
- long convoluted U-shaped tube attached to rete testes (series of ducts)
What are Interstitial Cells?
- endocrine cells between seminiferous tubules
- produce testosterone
- under influence of LH/ interstital cell stimulating hormone
What are Seroli Cells?
- support developing spermatids
- large “nurse” cells that shield spermatozoa from the body’s immune system
What is the Duct System?
-long convoluted tube that connects efferent ducts of testes with vas deferens
What is the Vas Deferens?
- muscular tube within the spermatic cord that connects the epididyis to the urethra
- in abdomen
- passes through inguinal ring then seperates from spermatic cord and connects with urethra
What is the Ampulla?
- enlargement of vas deferens just before it joins urethra
- contains glands that contribute material to semen
What is the Urethra?
- pelvic portion: entry point of vas deferens and accessory reproductive glands
- penile portion: runs length of penis
- sperm from vas deferens and secretions from acessory glands enter urethra and pumped out as semen
- carries urine from bladder
What are the Accessory Reproductive Glands?
- prostate, seminal vessicles, bulbourethral glands
- produce alkaline fluid to help neutralize acidity of female repro tract
- provide nutrient for sperm
What is the Prostate Gland?
- surrounds urethra
- has multiple ducts to carry secretions into urethra
What are Bulbourethral Glands?
- ducts enter urethra near caudal border of pelvis
- secrete mucinous fluid just before ejaculation that clears and lubricates urethra for passage of semen
What are Seminal Vesicles?
- present in all animals except dog and cat
- enter pelvic urethra in same area as vas deferens
What is the Penis?
- male breeding organ
- composed of muscle, erectile tissue, connective tissue
- urethra runs down center
- has large blood supply and many sensory nerve endings
- has 3 main parts
What are the 3 main parts of the Penis?
- root
- body
- glans
What is the Root of the Penis?
- bands of connective tissue (crura) that attach penis to pelvis
- covered in ischiocavernous muscle
What is the Body of the Penis?
- largest part
- composed of 2 bundles of erectile tissue
- connective tissue: spongy
- sinuses: tiny, blood filled spaces
What are the 2 areas of erectile tissue in the penis?
- corpus cavernosum (smaller)
- corpus cavemosum (larger)
What is the Glans of the Penis?
- distal end
- numerous sensory nerve endings
What is Prepuce?
- sheath of skin that encloses the penis when not erect
- inner part:smooth, moist mucous membrane
- inner part: normal skin
Canine Penis
- Os Penis:
- bone in penis
- urethra runs thru groove on ventral surface
- bulb of glans:
- enlargement toward rear of glans
- erection of bulb subsides in 15-20 min
What is the Sigmoid Flexure?
- s shape of non erect penis of bull, ram, boar
- higher proportion of CT to erectile tissue
- erection results from straightening of sigmoid flexure
What is an Erection?
- enlargement and stiffening of penis
- result from parasympathetic reflex triggered by sexual stimuli
- involves olfactory cues
- arteries dilate and increase blood flow
- veins are compressed against brim of pelvis reducing outflow of blood
What is Ejaculation?
- reflex expulsion of semen from penis
- has 2 stages
- movement of sperm to pelvic portion of urethra
- sphincter in urinary bladder closes
- rhythmic contraction of urethra pump out semen
- movement of sperm to pelvic portion of urethra
What are the functions of the Female Reproductive System?
- produce female sex hormones
- provide fertile ovum via oogenesis
- recieve sperm and provide site for fertilization
- provide environment for embryo to grow
- push offspring off into world
- provide nutrition for newborn
What are the Female Reproductive Organs?
- ovaries
- oviducts
- uterus
- cervix
- vagina
- vulva
What are Broad Ligaments?
- sheets of peritoneum by which the ovaries, oviducts and uterus are suspended
- Mesovarium
- Mesosalpinx
- mesometrium
What are Mesovarium Ligaments?
supports ovary
What are Mesosalpinx Ligaments?
supports oviducts
What are Mesometrium Ligaments?
- supports uterus
- contains blood vessels, nerves and fat
What are the Round Ligaments of Uterus?
- cord of fibrous tissue and smooth muscle in the broad ligament that extends from the uterine horn to the inguinal ring
- cut during a spay to allow removal of uterine horn
What is the Suspensory Ligament of Ovary?
- formed by the ovarian end of broad ligament attached to body wall in area of last rib
- during spay, it is “popped” to allow visualization and removal of ovary
What are the Ovaries?
- female gonads
- in dorsal abdomen near kidneys
What are the functions of the Ovaries?
- site of oogenesis
- animal is born with predetermined number of eggs
- production of estrogens and progestins
What are the Hormones that control Estrous Cycle?
- LH
- FSH
- Estrogen
- Progesterone
LH
- Source: Anterior Pituitary
- Effect:
- causes Granulosa cells to develop
- causes production of estrogen
- surge causes ovulation
FSH
- Source: Ant. Pituitary
- Effect:
- stimulates egg production
Estrogen
- Source: Ovary
- Granulosa Cells
- Effect:
- makes females receptive to males
- causes proliferation of uterine tissue
- produces female characteristics
Progesterone
- Source: Corpus Luteum
- Effect:
- prepares uterus for zygote (fert egg)
- maintains pregnancy
What is the Ovarian Cycle?
- each cycle consists of:
- development of ovum
- formation of corpus luteum
- degeneration of unripened follicles and corpus luteum
- influenced by FSH and LH
- number of follicles produced depend on species
What is Uniparous Species?
normally give birth to one offspring at a time
What are Mulitparous Species?
give birth to litters due to multiple ova production per cycle
What are Primary/Primordial Follicles?
- immature oocyte surround by a single layer of follicular cells
- stage that immature oocytes reside in until become activated to mature
- activted by FSH
- once growing called growing follicles
What are Growing Follicles?
- cells of the follice become thickened and start to multiply in layers around developing oocyte
- granulosa cells
- produce estrogen
- grow rapidly
What is the Antrum?
-large fluid filled space between granulosa cells
What are Mature Follicles (Graafian Follicle)?
- follicle has reached max size
- oocyte sits on top of granulosa cells mound (cumulus oophorus)
- surrounded by thin layer of cells (corona radiata)
- production of estrogen peaks (causes ovulation)
What is Ovulation?
- rupture of mature follicles and release of egg into oviduct as LH levels rise
- surface of mature follicle weakens and ruptures
- fluid from antrum is released, carrying egg
What are Oviducts?
- fallopian tubes
- extend from tips of uterine horns
What is the Infundibulum?
- enlarged opening at ovarien end of each oviduct
- not attached to oviduct
What is the Fimbriae?
- muscular projections form margin of infundibulum
- help properly position infundibulum
What is the Uterus?
- hollow, muscular
- womb
- where fertilized ovum implants
- forms part of placenta that keeps fetus alive
- grows during pregnancy
- Y shaped
What are the Layers of the Uterine Wall?
- Edonmetrium
- Myometrium
- Perimetrium
What is the Endometrium?
inner layer composed of simple columnar epithelium and glands that secrete mucus and other substances
What is the Myometrium?
- thickest layer
- made of smooth muscle
What is the Perimetrium?
- outermost layer
- covered by visceral peritoneum
What is the Cervix?
- smooth muscle sphincter between body of uterus and vagina
- controls access to lumen of uterus from vagina
- normally tightly closed, except during estrus and partuition
What is the Vagina?
- muscular tube extends caudally from cervix and connects with vulva
- recieves penis
- birth canal
- stretchable
- lined with mucous glands
What is the Vulva?
- only portion of female repro tract that is visible from outside
- labia:lips
- clitorus:”penis”
- vestibule:entrance to vagina
What is Polyestrous?
- animals that cycle continuously throughout the year if not pregnant
- cow
- pig
What is Seasonal Polyestrous?
- animals with seasonal variations in estrous cycles
- horse
- sheep
- cat
What is Diestrous?
- animals with 2 cycles per year
- dog
What is Monoestrous?
- animals with one cycle per year
- mink
- fox
What are the stages of the Estrous Cycle?
- proestrus
- estrus
- metestrus
- diestrus
- anestrus (in some species)
Proestrus
- follicles begin developing and growing
- output of estrogen increases
- linings of oviduct, uterus and vagina thicken to protect against breeding trauma
Estrus
- “heat”
- period of sex receptivity in femal
- estrogen level production peaks
- ovulation occurs near end of estrus in some species
- induced ovulator species remain in a prolonged state of estrus if not bred
Metestrus
- period after ovulation during which CL develops
- progesterone produced by CL temp. inhibits other
- lining of uterus prepared for implantation of fertilized egg
Diestrus
- CL at max size and exerting max effect
- if egg implants, CL is retained well into pregnancy
- if no pregnancy, CL degenerates at end of diestrus
Anestrus
- temporary ovarian inactivity
- seen in seasonal polyestrous, diestrous, monoestrous animals
What is False Pregnancy?
- pseudopregnancy
- animals act or look pregnant
- exaggerated diestrous period
- resolves spontaneously through use of hormones
What are signs of False Pregnancy?
- builds nest
- hoards/mothers toys
- mammary glands enlarge/produce milk
- pyometria
What is Copulation?
- act of breeding
- intromission, thrusting, ejaculation
What does Copulation trigger?
- oxytocin release
- from posterior pituitary gland of female
- causes contraction of smooth muscle of fem. repro. organs
Where is Semen deposited?
-upper portion of vagina
How are Spern transported?
- swimming
- contractions of uterus and oviducts
- action of cilia in oviducts
What is Capacitation?
-series of changes sperm undergo in female repro tract to increase fertilization
What are the “series of changes” undergo during Capacitation?
- change in ion movements
- influx of Ca++ thru cell membrane
- increase in cell’s metabolic rate
- increae in rate of sugar usage for energy
- release of digestive enzymes from acrosome
What is Fertilization?
- large # of sperm locate and swarm around ovum in oviduct
- some begining tunneling thru layers surrounding ovum
What is a Zygote?
- newly fertilized ovum
- male and female pronuclei join together
What is a Male Pronucleus?
nucleus of the fertilizing sperm
What is a Female Pronucleus?
nucleus of fertilized ovum
What is a Morula?
- solid mass of cells
- stage after zygote
What is a Blastocyte?
- hollow ball of cells with a mass of cells on one side
- future embryo
- stage of morula
- implants in uterus
What is Implantation?
- while cleavage is taking place, the zygote is slowly moving from the oviduct to the uterus
- blastocyte attaches in endometrium
- placenta forms as soon as blastocyte implants in uterus
What is Placenta?
-multilayers, fluid-filled, membranous sac that surrounds fetus and links it to the blood supply of the uterus
Where does the outermost layer of the placenta attach?
- uterine lining
- fetal and maternal vessels in close proximity
- site of exchange of blood, nutrients and wastes
- no direct contact between fetal and maternal blood occurs
What is the Umbillical Vein?
carries oxygen rich blood to fetus
What is the Umbillical Arteries?
carry deoxygenated blood back to the placenta
What is Amnion?
- membranous layer immediately surrounding fetus
- forms amniotic sac
- fetus floats in amniotic fluid
What is the Allantois?
- layer surrounding amniotic sac
- forms the Allantoic sac
- outside of sac is covered by chorion
What is Chorion?
- attaches to lining of uterus
- linked to fetus by umbilical cord
What is Urachus?
tube that connects bladder to allantoic sac
What is Diffuse?
- spread over the whole surface of placenta and uterine lining
- pigs
- horses
What is Cotyledonary?
- many, small seperate attachement sites (placentomes)
- ruminants
What is Placentome?
cotyledon on placental surface joins with caruncle in the uterine lining
What is Zonary?
- belt shaped attachments that encircles the placenta
- dogs
- cats
What is Discoid?
- placenta and uterus attached at a single disk shaped area
- humans
- primates
- rabbits
- rodents
What is the Gestation Period?
- time from fertilization of ovum of delivery of newborn
- time varies among species
- divided into 3 segments/trimesters
What is the First Trimester?
- embryonic period
- placenta develops
What is the Second Trimester?
- fetal period
- body tissues, organs and systems develop
What is the Third Trimester?
fetal growth period
What is Parturition?
-birth processes
What are the factors influencing birthing?
- size and weight of uterus and fetus
- hormonal changes
What are the Fetal Changes at birth?
- lungs expand and begin to function
- foramen ovale and ductus arteriosus close
What is the First Stage of Labor?
- uterine contractions
- myometrium contracts and presses fetus down against cervix
- sustained contractions cause cervix to gradually dilate
What is the Second Stage of Labor?
- delivery of newborn
- results from strong uterine and abdominal muscle contraction
- rupture of amniotic and allantoic sacs of placenta (usually precedes actual delivery of baby)
What is the Third Stage of Labor?
- delivery of the placenta
- placenta seperates from wall of uterus and is expelled by weaker uterine contractions
What is Involution of the Uterus?
- uterus gradually returns to nonpregnant size
- endometrium sloughs into lumen of uterus at sites of placental attachments
- myometrium continues mild contractions to move remaining uterine contents out through birth canal
- may take a few weeks to a month or more for completion