Reproduction Final

Dr. Burd Cal Poły

What is the purpose of reproductive behavior?

• To promote the opportunity for copulation

• Increase the probability that the sperm and egg will meet

What are the three stages of reproductive behavior in males?

• Pre copulatory stage

• Copulatory stage

• Post copulatory stage

What are the three stages of reproductive behavior in females?

• Attractivity

• Proceptivity

• Receptivity

Describe the stages in pre copulatory behavior in males

• Search for sexual partner

• Courtship

• Sexual arousal

• Erection

• Penile protrusion

Describe the stages in copulatory behavior in males

• Mounting

• Intromission

• Ejaculation

Describe the stages in post copulatory behavior in males

• Dismount

• Refractory period

• Memory

Describe attractivity behavior in females

• What attracts males to the females

  • Includes postures, vocalizations, behaviors, chemical cues (pheromones)

Describe proceptivity behavior in females

• Behaviors from females that stimulate males to copulate

  • Examples include head butting or mounting females mouthing males

Describe receptivity behavior in females

• Copulatory behavior of females that ensures insemination

  • Examples: immobility or standing response

True or false: reproductive behaviors are sexually differentiated

True

How are reproductive behaviors controlled?

• Endocrine system

What are the main sensory inputs for reproductive behavior?

• Olfaction

• Vision

• Audition

• Tactility

Why would we have bulls watch another bull mount and ejaculate?

• It usually ‘pre stimulates’ bulls, reduces stimulation time, and increases sperm harvest

What organ detects pheremones?

• Vomeronasal organ

What is the flehmen response?

• A head elevation and curling of the upper lip so the male can evaluate pheromones better

• Can sometimes be seen by females

True or false: Auditory stimulation can serve as a long-range signal.

True

True or false: Visual signals are valuable for long-range signals.

False → they are good for close encounters

What is the last type of stimulation before copulation occurs?

• Tactile stimulation

What are the requirements for the penis to erect?

• Elevated arterial blood inflow

• Dilation of corporal sinusoids

• Restricted venous outflow

• Relaxation of the retractor penis muscle

• Elevated intrapenile pressure

Describe how the penis becomes erect

• Erotogenic stimuli are present in nonadrenergic noncholinergic (NANC) neurons and fire releasing nitric oxide

• Nitric oxide activated an enzyme, guanylate cyclase, which converts guanylate triphosphate (GTP) to cycle guanosine monophosphate (cGMP) and causes smooth muscle to relax

• Cavernous sinusoids engorge with blood and intracorporal pressure increases

• Venules are compressed which traps blood causing an erection

What is included in copulatory behavior?

• Mounting

• Intromission

• Ejaculation

What is ejaculation caused by?

• Intromission

• Stimulation of the glans penis

• Forceful muscle contraction

True or false: Ejaculation can’t be stopped once the process has started

True

What factors influence the amount of time a refractory period lasts?

• Degree of sexual rest prior to copulation

• Age

• Species

• Degree of female novelty

• Number of previous ejaculations

What can enhance reproductive behavior?

• Introducing novel stimulus animals

• Changing stimulus settings

How can you maximize the output of spermatozoa per ejaculate?

• Sexual preparation

  • False mounting

  • Restraint

  • False-mounting plus restraint

What should the design of an artificial vagina accomplish?

• Provide a suitable environment for stimulation of the glans penis

• Provide an environment that prevents damage to the penis

• Provides an environment that maximizes sperm recovery and minimizes sperm insult

Describe the sequence of events that follows deposition of sperm

• Immediate Transport'

  • Retrograde loss (sperm falling out)

  • Phagocytosis

  • Entrance into cervix/uterus

• Cervix

  • 'Privileged pathways’

  • Removal of non-motile sperm

  • Removal of some abnormalities

• Uterus

  • Capacitation initiated (finale maturation of sperm)

  • Phagocytosis

• Oviduct

  • Docking to oviductal cells

  • Capacitation completed

  • Hyperactive motility

• Fertilization

  • Acrosome reaction

  • Spermatozoon penetrates oocyte

  • Male and female pronuclei form

what causes spermatozoa to be lost in the female tract?

• Phagocytosis by neutrophils

• Retrograde transport

What are the two phases that spermatozoa transport consists of?

• Rapid and sustained phase

What is crucial that sperm must do during the sustained phase to survive?

• They have to ‘dock’ in the epithelium of the lower isthmus

  • signals cascade in the sperm that promotes viability

True of false: the sperm swims up to the oviduct

• False: the uterus transports it through contractions and fluids

What is the name of the pit lining that allows sperm to move easier?

• Privelaged pathway

  • Lined with sialomucin

What is the name of the mucus produced at the tips of the cervical canals?

• Sulfomucin

What is spermatozoal capacitation?

The time that sperm takes to become mature in the female reproductive tract

What can be used to activate sperm in the female to remove the caps that prevent them from fertilizing?

• Calcium

What type of motility occurs in the oviduct once the sperm arrive?

• Hyperactive motility

  • Frenzied movement that is localized in a small area

What is needed for the sperm to bind to the zona pellucida?

• Zona-binding proteins on the spermatozoal membrane

What is the name of the physical gap between the oocyte cytoplasm and the zona pellucida?

• Perivitelline space

What does the zona pellucida consist of?

• Three glycoproteins

  • ZP1, ZP2, and ZP3

Describe how the sperm binds to the oocyte

• The sperm has zona-binding regions that attaches to ZP3 that causes physical attachment

• The sperm also has acrosome reaction promoting regions that interact with ZP3 which causes sperm plasma membrane to fuse

• Essentially more ZP3 means better binding

What prevents penetration of additional spermatozoa to an egg?

• Cortical reaction

How do cortical reactions occur?

• After membrane fusion between the oocyte and sperm, cortical granules undergo exocytosis and their contents are released into the perivitelline space

• Known as a Zona Block

What is polyspermy?

• Fertilization of an oocyte by more than one spermatozoon which results in embryo death

True or false: the closer you are to mating (ovulation) the increased pregnancy rates

True

True or false: sperm must be delivered to the proper anatomical region of the female tract for successful artificial insemination

True

What are the four steps that must be achieved before the embryo can attach to the uterus?

• Development within the confines of the zona pellucida

• Hatching of the blastocyst from the zona pellucida

• Maternal recognition of pregnancy

• Formation of the extraembryonic membranes

What are the stages to get from ootid to blastocyst

• Ootid → zygote → 2-celled embryo → morula → early blastocyst → hatching blastocyst → expanded blastocyst

What do the outer blastomeres that line the morula become?

• Placenta

What do the inner blastomeres that line the morula become?

• Fetus

What causes zona pellucida to break for a blastocyst to leave?

• Trophoblasts

What three forces govern the hatching of the blastocyst?

• Growth and fluid accumulation within the blastocyst

• Production of enzymes by the trophoblastic cells

• Contraction of the blastocyst

What does the extra embryonic membranes of the reattachment embryo consist of?

• Yolk sak

• Chorion

• Amnion

• Allantois

When yolk sac disappears and allantois grows what does that mean?

• Embryo is viable

What is the job of trophoblasts?

• Secretes IFN-t which inhibits oxytocin production so PGF2a is not produced

What is the job of trophoblasts IN SOWS?

• Estradiol is the recognition of pregnancy so trophoblasts still make estrogen and PGF2a but it is moved away from endometrium and degraded

What is unique about the equine pregnancy?

• Conceptus moves around the uterus so maternal recognition is present

What are the advantages of embryo transfer?

• Circumvention of seasonal reproduction

• Enhanced generation of offspring in monotonous species

• Assisted reproduction for infertility in humans

• Enhanced reproductive potential of endangered species

• Enhanced genetic diversity across a wide geographical region

What does a successful embryo transfer involve?

• Synchronizing the cycles of donors and recipients

• Super ovulation of the donor

• Artificial insemination of the donor female

• Recovery of embryos from the donor

• Maintenance of viable embryos in vitro

• Transfer of embryos to recipient females

How is oocyte recovery from ovaries accomplished?

• Surgically exposing the ovary and aspiring follicles

• Non-surgically aspirating follicles utilizing ultrasonography

• Aspirating follicles postmortem in an abattoir

What are the final prepartum steps of reproduction?

• Formation of a placenta

• Acquisition of endocrine function of the placenta

• Initiation of parturition

What are the different types of placentas?

• Diffuse

• Zonary

• Discoid

• Cotyledonary

Describe diffuse placentas

• Uniform distribution of chorionic will that cover the surface of the chorion

• Example: pigs and mares

Describe zonary placentas

• Band-like zone of chorionic villi

• Example: dogs and cats

Describe discoid placentas

• Regionalized disc.

• Maternal recognition from blood

• Example: rodents and primates

Describe cotyledonary placentas

• Numerous, discrete button-like structures

• Example: ruminants

What type of placental layer do diffuse and cotyledonary placentas have?

Epitheliochorial → 6 layers that proteins have to travel through

What type of placental layer do discoid placentas have?

Hemochorial → 3 layers that proteins have to travel through

What type of placental layer do zonary placentas have?

Endotheliochorial → 5 layers that proteins have to travel through

What can the hormones that the placenta discrete do?

• Stimulate ovarian function

• Maintain pregnancy

• Influence fetal growth

• Stimulate mammary function

• Assist in parturition

What are the three stages of parturition?

• Stage 1: initiation of myocetrial contractions

• Stage 2: Expulsion of the fetus

• Stage 3: Expulsion of the fetal membrane

What are the four major events of the puerperium?

• Myometrial contractions and expulsion of lochia

• Endometrial repair

• Resumption of ovarian function

• Elimination of bacterial contamination of the reproductive tract

When do postnatal changes occur in the mammary gland?

• Between birth and puberty

• Between puberty and pregnancy

• During pregnancy

• During lactation

• During involution

What is required for milk ejection?

• Sensory activation

• Neural activation of the hypothalamus

• Oxytocin release into the blood

• Contraction of the myoepithelial cells

• Mechanical transfer of milk from alveoli into ducts and family into the teat/nipple