Topic 89 - Phases of the estrus cycle, species specificities in the sexual cycle

Question 1

Words to include in phases of the estrus cycle

Answer 1

• Consecutive ovulations
  
  • Cyclic
  • Endocrine centers are activated at beginning of puberty
    
    • Sensitive to cyclic events
• Estrus
  
  • Ovary - uterine duct - uterus -cervix - vagina
  • Changes at hormonal and behavioral level
  • 21 days

Phases of estrus bases on ovarian functions

• Follicular phase
  
  • Days
  • Follicle developement
  • E2 domination of follicle
    
    • Sexual receptivity
• Ovulatory phase
  
  • Minutes
• Luteal phase
  
  • Days
  • P4 domination
  • Active corpus luteum

Phases of estrus cycle based on the behavioral, morphological changes

• Follicular phase
  
  • Proestrus
  • Estrus
• Luteal phase
  
  • Metestrus
  • Diestrus

Question 2

Words to include in species specificities in the sexual cycle​

Answer 2

• Seasonality
  
  • Continous estrus
  • Periodical estrus (seasonal estrus)
• Type of ovulation
  
  • Reflex ovulation
    
    • Induced ovulation (?)
  • Spontaneous ovulation
• Continous estrus
  
  • Beginning of puberty
  • 21 days estrus cycle
  • No anestrus (only during lactation)
• Seasonal estrus
  
  • Hasanon-cyclic period → anestrus
  • Seasonal monoestrus
    
    • One estrus cycle per active season
  • Seasonal polyestrus
    
    • Several estrus cycles per active season

Difference between species

• Selection of dominan follicle in large animals
• Length of cycle
• Type of estrus
  
  • Continous VS seasonal animals
  • Induced VS sponaneous ovulators
• Seasonal animals
  
  • Dog
  • Sheep (seasonal polyestrus)
  • Goat
  • Horse (seasonal polyestrus
• Reflex ovulator animals
  
  • Cat
  • Ferret
  • Rabbit
  • Llama
• Rabbit
  
  • Continous maturation of follicles → follicular atresia
  • 2-3 estrus period
  • Anestrus
• Sheep
  
  • Seasonal polyestrus
  • Estrus: autumn
  • Fertilization: autumn / winter
  • Pregnancy: 144 days (5 months)
• Horse
  
  • Seasonal polyestrus
  • Estrus: spring
  • Fertilization: spring / early summer
  • Pregnancy: 336 days (11 months)
• Dog
  
  • Seasonal monoestrus
  • Stages of estrus cycle:
    
    • ​Proestrus
      
      • 3-20 days
      • E2 level peak
      • P4 production
      • Follicle development
      • LH level ↑
    • Estrus
      
      • 3-20 days
      • Fertile
      • Ovulation 48 hours after LH peak
      • E2 level ↓
      • P4 level ↑
    • Diestrus
      
      • Pregnant: 63 days
      • Non-pregnant: 70 days
      • P4 level ↑
    • Anestrus
      
      • 4 monts
      • P4 level low

Question 3

Phases of the estrus cycle

Which part of the female reproductive system does the estrus affect?

Answer 3

• In estrus, changes occur simultaneously at several levels:
  
  • Ovary
  • Uterine duct
  • Uterus
  • Cervix
  • Vagina
• Changes are also manifested at the hormonal and behaviroal levels

Question 4

Phases of estrus

When does the estrus cycle take place

Answer 4

Estrous cycle is the period between two consecutive ovulations

At the beginning of puberty, endcrine centers are activated and become sensitive to cyclic events, which cause morphological and behavioral changes

Question 5

Phases of the estrus cycle

Name and explain the different phases of the estrus cycle

Answer 5

• Phases of estrus cycle based on ovarian functions:
  
  1. ​Follicular phase
     
     • ​Days
     • Follicular development
     • E2 domination of the follicle
       
       • Initiating sexual receptivity
  2. Ovulatory phase
     
     • ​Minutes
  3. Luteal phase
     
     • ​​Days
     • P4 dominance
     • Period when corpus luteum is active
• Repeats every 21 days (if no fertilization)
• Phases of the estrus cycle based on behavioral, morphological changes:
  
  1. Proestrus
     
     • 2-4 days
     • ​End of follicular maturation
     • P4 ↓
     • E2 ↑
     • Endometrium secretes fluid
     • Female is not ready for copulation
  2. Estrus
     
     • ​E2 high (dominant)
     • ​Sexual receptivit
     • Ovulation usually occurs
     • Vulva becomes swollen
     • Cervix is open
     • Secretion​
  3. Metestrus
     
     • 2-5 days
     • Beginning: P4 and E2 levels are low
     • ​CL → ​P4 ↑
     • Corpus formation
     • Beginning of P4 secretion
  4. Diestrus
     
     • ​P4 high
       
       • Prepares the uterus for early embryo development
     • Longes period of estrus
     • Ends when CL diminishes
     • Luteolysis
  5. Anestrus:
     
     • Sexual inactivity
     • ​Lack of estrus cycle (eg. during lactation, pathological conditions)
     • Typically a seasonal event
       
       • Controlled by light exposure trough pineal gland → melatonin release
• Follicular phase = proestrus, estrus
• Luteal phase = metestrus, diestrus

Question 6

Species specificities in the sexual cycle

Give the general differences between species

Answer 6

1. Selection of dominant follicles in large animals
2. Length of cycle
   
   • ​Primates VS farm animals
3. Types of estruses
   
   • ​Continous VS seasonal animals
   • Induced VS spontaneous ovulators

• Based on the seasonality
  
  • ​Continous estrus
  • Periodical estrus (seasonal estrus)
    
    • ​​Seasonal monoestrus (one estrus cycle in each secually active season​)
    • Seasonal polyestrus (more than one ​estrus cycle in each secually active season​)
• Based on the type of ovulation
  
  • ​Reflex ovulation
  • Spontaneous ovulation
• Continous cycle
  
  • ​No anestrus (only during lactation)

Question 7

Species specificities in the sexual cycle

Name the animal with continous cycle

Answer 7

Cow

Swine

Question 8

Species specificities in the sexual cycle

Name species with seasonal estrus

Answer 8

1. Dog
2. Sheep (seasonal polyestrus)
3. Goat
4. Horse (seasonal polyestrus

Question 9

Species specificities in the sexual cycle

Name the animals with reflex ovulation

Answer 9

Cat

Ferret

Rabbit

Llama

Question 10

Species specificities in the sexual cycle

Sheep

Answer 10

• Seasonal polyestrus
• Seasonal anestrus
• Estrus cycle starts in autumn
• Fertilization: autumn / winter
• Pregnancy: 144 days (5 months)
• Parturition the next spring

Question 11

Species specificities in the sexual cycle

Horse

Answer 11

• Seasonal polyestrus
• Seasonal anestrus
• Estrus cycle starts in spring
• Fertilization: spring / early summer
• Pregnancy: 336 days (11 months)
• Parutition in the next spring

Question 12

Species specificities in the sexual cycle

Cattle

Answer 12

• Continous, spontaneous estrus
• Pathological anestrus (except in beef cattle during lactation)
• Pregnancy: 279 days
• Ovulation after estrus

Question 13

Species specificities in the sexual cycle

Swine

Answer 13

• Continous, spontaneous estrus
• Anestrus during lactation
• Pregnancy: 114 days
• Ovulation in the last third of estrus

Question 14

Species specificities in the sexual cycle

Cat

Answer 14

• Seasonal polyestrus
• Induced estrus
• Anestrus seasonal
• Pregnancy: 58-65 days
• Ovulation 24-30 hurs after copulation

Question 15

Species specificities in the sexual cycle

Rabbit

Answer 15

• Continous maturation of follicles and atresia
• Induced ovulation
• Pregnancy: 31 days
• Ovluation 10-14 hours after copulation
  
  • Can be fertilized by a copulation at any time