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:star: REPRODUCTION :star: ((2) Reproductive cycles (External Factors…

- - - - The follicular cycles are distinct to the extent that follicle regression usually begins before the onset of the growth of the next follicle
        
        1st dominant follicle
        
        :lock: Regress about midluteal phase
        
        3rd dominant follicle
        
        2nd dominant follicle
        
        If it begun to regress at the time of CL regression, a third follicle develops
      - :timer_clock: development of the antral follicle to the point of ovulation estimated to be 10 days in domestic animals, slightly longer in some primates
    - - Preovulatory surge of LH begins about 24 hours before ovulation
      - An oocyte-inhibiting factor prevents the oocyte from resuming meiosis
      - A luteinizing-inhibiting factor prevents the granulosa from prematurely being changed into luteal tissues
      - Estrogen used by the follicles to:
        
        Stimulate the growth
        
        Stimulate the development of the granulosa
        
        Signal the hypothalamus and anterior pituitary as to the readiness of the follicles for ovulation
  - - - In :rat:, prolactin is important luteotropin
      - In domestic animals, LH is important luteotropin
    - - :pencil2: Prepares the uterus for the iniation and maintenance of pregnancy
      - :pencil2: Production begins within 24 hours of ovulation
    - - :sunflower: Usterus is responsible for control of the duration of the life span of the CL
      - In large domestic species, regression of the CL is initiated by:
        
        :pencil2: Uterine synthesis
        
        :pencil2: Release of PGF2a at about 14 days post-ovulation
      - Countercurrent transfer involves the
        
        Moment of molecules across the blood vascular system from higher concentrations in the venous effluent (utero-ovarian vein) to an area lower concentration (ovarian artery)
        
        Systemic transfer involves passage of the molecules thru the general circulatory system
    - - Presence of an embryo results in :
        
        :warning: The blockage of PGF2a synthesis
        
        :warning: A continueance in luteal activity
      - The absence of a uterine horn result in a lengthened luteal phase in animals in which the ipsilateral horn controls the CL (local control)
      - In nonpregnant large domestic animals, inflammatory responses of the endometrium caused by:
        
        Bacterial contamination :star:
        
        Result in significant synthesis and release of PGF2a
        
        Leading to
        
        :fire: Premature luteolysis
        
        :fire: A shortening of the estrous cycle
  - - - Initial Follicular Phase
      - Subsequent Luteal phase
        
        :rat: Ovarian cycle is extended by copulation
        
        The life span of CL is only 1 to 2 days in the absence of copulation
        
        :pencil2: Copulation initiates the release of prolactin
- - - - Lactation
        
        :check: Suppressive effects on ovarian activity
        
        Concepts of lactational suppression of ovarian activity
        
        The importance of suckling with its related stimulation of prolactin synthesis
      - Nutrition
      - Photoperiod
        
        Pineal gland
        (main translator)
        
        :check: Produce melatonin in response to darkness
        
        The response to photoperiod is different among sp;
        
        :cat: & :horse: positively affected by :arrow_up: light
        
        :goat: & :sheep: are positively affected by :arrow_down: photoperiod
      - Animal interaction
      - Pheromones
        
        :male-scientist::skin-tone-2: Chemical compounds that allow communication among animals thru the olfactory system
        
        Sex pheromones
        
        Important for the attraction of the male to the female at the time of sexual receptivity :<3:
    - - :warning: Can affect ovarian activity in the postpartum period
  - - - In domestic animals only :<3:
      - Limited period :fire:
      - Proestrus begins within 48 hours after end of luteal phase :tada:
      - Stages in estrous cycle
        
        Metestrus :unlock:
        
        :alarm_clock: Period of initial development of the CL
        
        Diestrus :unlock:
        
        :alarm_clock: Period of mature phase of the CL
        
        Estrus :explode:
        
        :alarm_clock: Period of sexual receptivity
        
        Proestrus :explode:
        
        :alarm_clock: Period of follicle development, occuring subsequent to luteal regression and ending at estrus
    - - :monkey_face: In primates only
      - Begins within 24 hours of the end of the luteal phase :check:
  - - - Menopause
        (end to ovarian activity) in primates
        
        Results from the depletion of oocytes
      - :green_cross: recognizes in domestic animals
  - - - Establishment of sexual behavior depends on:
        
        :one: Exposure
        
        :two: Lack of exposure
      - Testostrone
        
        :green_cross: hypothalamus become feminized :woman::skin-tone-2:
        
        :check: caused masculinization :man::skin-tone-2:
        
        Important for libido in :female_sign: primates
      - :warning: Effect of hormones :warning:
        
        Synergism between hormone is often important for sexual receptiveness
        
        The sequence of exposure to hormones
        
        The magnitude of change in hormone concentration that affects sexual behavior is small
- - - - Female:
        :check: Developing gonad is ovary
        :check: The wolffian duct regresses
        
        Mullerian duct develops into:
        
        Uterus
        
        Cervix
        
        Oviduct
        
        Vagina
      - Male:
        :check: Rete testis produces mullerian-inhibiting factor, which causes regression of the mullerian ducts
        :check: Wolffian duct is maintained in the male
  - - - :arrow_up: Follicular phase
      - :arrow_down: Luteal phase
    - - :red_flag: Pulsatile
        
        The pattern is driven by pulsatile secretion of GnRH from the hypothalamus
        
        :warning: Importance:
        
        If GnRH is administered in a continuous manner, the system can be downregulated
    - - Important in the reproductive process
        
        Mainly is effects on:
        
        :pencil2: Mammary gland
        
        :warning: Positive feedback :warning:
        
        :pencil2: Lactation in mammals
    - - Duration is short, 12 - 24 hours
      - To induce changes within the follicle that lead to its rupture (ovulation)
    - - :wilted_flower:Estrogen
        
        Characterized by:
        
        Sensitivity (effective a low concentration)
        
        Rapid onset (within a few hours)
      - :wilted_flower:Progesterone
    - - Major differences:
        
        The need for positive-feedback release of gonadotropins in :male_sign: does not exist
  - - - Produces
        
        FSH :star:
        
        LH :star:
        
        Prolactin :star:
    - - Secrete
        
        :<3: Peptide hormones
        
        :<3: Protein
  - - - FSH directs the granulosa to transform the androgens to estrogens
    - - :pencil2: Permits the preovulatory surge of LH to cause ovulation
- - - - Meiosis
        
        Occus only during the processes of oogenesis and spermatogenesis
      - Spermiogenesis
        
        The newly formed spermatids continue to differentiate w/o dividing to form mature spermatids
        
        Major features:
        
        Condesation and elongation of the nucleus
        
        Formation of the acrosome from the Golgi apparatus
        
        Formation of the flagellum
        
        Extensive shedding of cytoplasm
      - Spermatocytogenesis
        
        :pencil2: Type A spermatogonia become type B spermatogonia, which further divide thru mitosis to produce primary spermatocytes.
        
        :pencil2: Type A spermatogonia produce other spermatogonia that are not yet commited to the immediate spermatozoal production process, thus maintaining a population of stem cells
  - - - Inhibin :<3:
        
        Produced by Sertoli cells
        
        Stimulates steroidogenis in Leydig cells
      - Gonadal Steroids :hearts:
        
        To supress FSH release
  - - - :check: When male is first able to produce sufficient no. of sperm to impregnate a female
      - :check: Ejaculate contains 50 x 10^6 spermatozoa, of which >10% are motile
      - :check: Occur months to years later, depends on species
    - - :pencil2: Hypothalamus,a pivotal role in the initiation of puberty
  - - - Many individuals receiving anabolic steroids are peripubescent or prepubescent
      - Altered to maximize their anabolic action & to minimize their androgenic side effects
  - - - The presence of individual accessory glands, the testicular orientation, the type of penis, and the site of semen deposition in the female are dependent on the species
      - Scrotum:
        :check: Present in all domestic animals
        :check: Protects and thermoregulates the testes
        :check: Skin pouch with a subcutaneous fibroelastic and muscular layer (tunica dartos)
      - Testes:
        :red_flag: Responsible for steroidogenesis
        :red_flag: Production of androgens & generaton of haploid germ cells by spermatogenesis
        Both occur in the Leydig cells (LC) & the seminiferous tubules (ST) respectively
        
        :<3: The adluminal compartment :<3:
        (a special environment where spermatocytes undergo meiosis and continue their meiotic divisions to differentiare intro spermatids and finally into spermatozoa)
        
        :<3: The interstitial tissue compartment :<3:
        (containing the LC, surrounds the ST and bathes them with testosterone-rich fluid)
        
        :pencil2: Cryptorchidism
        (Failure of one or both of the testes to descend into the scrotum
        
        Incapable of producing normal spermatozoa
        
        A bilaterally cryptorchid male would be sterile
        
        Genetic inheritance
        
        :explode: Seminiferous tubules
        
        :warning: transports the spermatozoa and seminiferous tubular fluid into the epididymis
        
        Epididymis :fire:
        
        Conduit for spermatozoa
        
        Provide special environment
        
        Body
        
        Tail
        
        Head
        
        :explode: The cauda epididymis and Deferent ducts (vasa deferentia)
        
        :warning: Serve as a storage depot for mature spermatozoa; extragonadal sperm reserves
        
        :<3: The basal compartment :<3:
        (contains spermatogonia, which divide thru mitosis)
        
        Seminal Vessicles :fire:
        
        :warning: two small glands that store and produce the majority of the fluid that makes up semen
        
        Bulbourethral glands :explode:
        
        Also known as Cowper's gland
        
        :warning: Add fluids to semen during the process of ejaculation
        
        Prostate glands:explode:
        
        :warning: To secrete prostate fluid, one of the components of semen
      - Penis:
        :check: Copulatory organ of males
        :check: 1 tunica albuginea
        2 the corpus cavernosum penis
        3 corpus spongiosum penis
        :check: Erection is a psychosomatic event that involves mutually occuring actions of the vascular, neurological, and endocrine systems
    - - The release of spermatozoa and accessory gland fluids intro the pelvic urethra
        
        Sympathetically mediated thracolumbar reflex contraction of the smooth muscle in the ductus deferens and accessory glandds
    - - The forceful expulsion of semen from the urethra
        
        Parasympathetically mediated sacral reflex that induces rhythmic contractions of the:
        
        Bulbospongiosus
        
        Urethralis muscles
        
        Ischiocavernosus
- - - - Cisterns:
        In :goat: and :cow2:
        
        :pencil2: Located in the ventral part of the gland and into which all main ducts empty
    - - Source of the mammary glands
        
        :sunflower: Embryonic ectoderm
      - Parenchyma
        (milk-secreting cells)
        
        :sunny: Develops thru proliferation of epithelial cells that arise from the primary mammary cord
    - - :white_flower: Formed by the median suspensory ligament
      - If the suspensory system absent, the mammary gland system would soon break down from the weight of the milk :frowning_face:
  - - - Growth hormone is also important for lactogenesis
  - - - Fetal mammary development, not to be driven by hormones
    - - :sunny: Adrenal steroids
      - :sunny: Growth hormone
      - :sunny: Alveoli under the control of progesterone and prolactin
      - :sunny: Estrogen
  - - - Composed of:
        
        Triglycerides
        
        Free fatty acids
        
        Diglycerides
        
        Phospholipids
        
        Monoglycerides
        
        Steroids
    - - Formed under the direction of lactose synthetase
        
        An enzyme composed of a-lactalbumin (a milk protein) & galactosyl transferase
      - Absence of lactase, lactose can have an osmotic effect in the GIT, which could lead to diarrhea
    - - Main proteins produced by alveolar cells
      - Caseins can be removed (as a curd) from milk thru a process called curdling or coagulation
  - - - Which caused:
        
        Contration of muscle cells that surround the myoepithelial cells
        
        Movement of milk into the ducts and Cisterns
  - - - Milking usually stops at 305 days of lactation, so that the animal can prepare the mammary gland for the next lactation
    - - Hormone administration (estrogen & progesterone)
      - Enhanced by Growth hormone
      - Increased by photoperiod exposure
  - - - Mastitis (inflammation of the gland)
        
        Prevalent in dairy cattle and dogs
        
        :syringe: anti inflammatory & antibacterial agents
      - Neoplasia (the presence or formation of new, abnormal growth of tissue)
        
        Prevalent in intact dogs and cats
        
        :syringe: Ovariectomy
    - - Passive transfer of RBC agglutinating antibodies by the ingestion of colostrum (mare)
      - Hypocalcemia caused by the transient drain of calcium that occurs with initiation of lactation (dairy cattle) or during the perinatal period (dog)
  - - - The former can stand a longer interval to first suckling than can the latter
    - - Results in:
        
        Stasis of the bowel (ileus)
        
        Can promote neonatal sepsis (overwhelming infection)
    - - :goat: :horse: :sheep: :
        Up to 2 hours
      - :rabbit: : 24 hour
      - :cat: :dog: :pig: :
        1 hour or less
- - - - The embryo apparently produces substances that modify uterine production of PGF2a
      - Trophoblastin produced before day 14 of pregnancy
      - In :cat: that CL lasts for 35 - 40 days after ovulation regardless of the presence of pregnancy
        
        A placental hormone that produced in :cat:, relaxin. (synergizes with progesterone for the support of pregnancy)
      - In :pig: a minimal number of embryos need to be present about 4
      - :dog: does not extend its luteal phase during pregnancy; the luteal phase in the nonpregnant animal is slightly longer (70 days) than in pregnant animals
    - - Production of progesterone
      - Placental production of suffiecient progesterone to maintain pregnancy occurs later in domestic animals
        
        :horse: : Day 70 of 340 day gestation
        
        :cat: : Day 45 of 65 day gestation
        
        :sheep: : Day 50 of 150 day gestation
        
        Placenta never produces enough progesterone to support pregnancy in :cow: :goat: :pig:
    - - :check: Fusion of an oocyte
      - :check: Spermatozoon within the oviduct
  - - - Maintaining the quiescence of the myometrium
      - Promoting a tightly contracted cervix
    - - :star: Playing important supporting roles
    - - :pencil2: Occurs thru the Ferguson reflex
      - Synergistic with PGF2a in promoting contraction of the uterus
    - - Important hormone for the preparation of parturition
      - Responsible for the separation of the pubic symphysis thru relaxation of the interpubic ligament
      - Cause the ligaments & associated muscles surrounding the pelvic canal to relax
        
        :check: Allows the fetus to expand the pelvic canal to its fullest potential
    - - 2nd stage of parturition
        
        :fountain_pen: Actual delivery process
      - 1st stage of parturition
        
        :fountain_pen: Presentation of the fetus at the internal os of the cervix
      - 3rd stage of parturition
        
        :fountain_pen: Delivery of the fetal membranes