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Vet Med Year 1 > Gestation > Flashcards

Flashcards in Gestation Deck (28)
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1
Q

Review of fertilisation and implantation

A
Sperm capacitation 
\/
Hyperactivation
\/
Binding to zona pellucida
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Acrosome reaction
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Penetration of zona pellucida
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Sperm – Oocyte binding Fertilisation
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Zygote cleavage 
\/
Blastocyst formation and hatching
2
Q

Maintenance of pregnancy

A

• Progesterone is required to maintain pregnancy
• Progesterone secreted by the corpus luteum (CL) throughout
pregnancy in some species
• The placenta takes over the secretion of progesterone during gestation in some species
• Increase in the oestrogen:progesterone ratio induces parturition

3
Q

Placenta

A

• Diverse range of placental structures
• Classified by extent and type of attachment, distribution of chorionic villus,
shape, type of implantation.
• Facilitate gas and nutrient exchange and endocrine support for the developing embryo and foetus

4
Q

Foetal membranes

A

• There are four foetal membranes in mammals. 1. chorion
2. yolk sac 3. amnion 4. allantois
• They are derived from the zygote. Their main functions are to isolate and protect the foetus and to form the placenta.

5
Q

Foetal Membranes

A
  • Two types of foetal membranes that form: Choriovitelline (Non mammals and marsupials) Chorioallantoic (ruminants, pigs)
  • Horses, carnivores and rodents are Choriovitelline then chorioallantoic
6
Q

Choriovitelline

A

A choriovitelline placenta is a placenta formed by the yolk sac and chorion. In a choriovitelline placenta, the yolk sac fuses with the chorion and subsequently wrinkles develop that hold the embryo to the uterine wall and the embryo, thus forming the choriovitelline placenta.

7
Q

Chorioallantoic

A

A placenta in which the allantoic mesoderm and vessels fuse with the inner face of the serosa to form the chorion.

8
Q

Horses, carnivores and rodents are

A

Choriovitelline then chorioallantoic

9
Q

Placental type 2; Shape and point of villous contact

A
  • Discoid (rodents)
  • Cotyledonary (ruminants)
  • Zonary (dogs and cats)
  • Diffuse (horses and pigs)
10
Q

Discoid

A

A placenta in which part of the chorion remains smooth, while the other part interacts with the endometrium to form the placenta. The maternal blood cells are in direct contact with the fetal chorion.

11
Q

• Cotyledonary

A

A type of chorioallantoic placenta in which the villi are grouped into tufts or balls separated by regions of smooth chorion

12
Q

Zonary

A

The placenta takes the form of a complete or incomplete band of tissue surrounding the fetus. Seen in carnivores like dogs and cats, seals, bears, and elephants

13
Q

Diffuse

A

a placenta made up of villi diffusely scattered over almost the whole surface of the chorion (as in whales, swine, and horses)

14
Q

maternal; Foetal interface

A

The maternal-fetal interface is composed of the maternally derived decidua and the fetally derived placenta (Fig. 1). In both mice and humans, the placenta develops from the trophectoderm of the blastocyst. During implantation, invading trophoblasts anchor the blastocyst to the specialized uterine epithelium (the decidua), on which placentation ensues.

15
Q

Foetal membranes of the dog

A
  • choriovitelline then chorioallantoic, • zonary, central,

* endotheliochorial

16
Q

Mammary Gland

A
  • Structure of mammary gland, supportive tissues, circulation
  • Species diversity
  • Hormonal control of mammogenesis, lactogenesis, galactopoiesis • Mechanism of milk ejection
  • Milk composition and its affecting factors
17
Q

Streak canal

A

-Functions to keep milk in udder and bacteria out of udder

18
Q

Teat cistern

A
  • Duct in teat with capacity of 30-45 millilitres. Separated from streak canal by folds of tissue called Furstenberg’s rosette
19
Q

Gland cistern

A

Separated from teat cistern by the cricoid fold. Holds up to 400 millilitres of milk, collecting area for the mammary ducts

20
Q

Lactogenesis

A

The onset of milk secretion, changes in oestrogen and progesterone concentrations and prolactin upon expulsion of the placenta

21
Q

Galactopoiesis

A

The maintenance of lactation, stimulated by suckling and prolactin hormone

22
Q

Involution

A

Termination of milk secretion and mammary gland regression

23
Q

Parturition

A
  • Process by which conceptus is expelled from the uterus (Conceptus consists of foetus, placenta and foetal membranes)
  • Parturition requires Cervical remodelling
  • Initiated by foetus by activation of foetal HPA axis
  • Co-ordinated
  • Uterine contractions regulated by Oxytocin and prostaglandins F2α • Delivery of placenta regulated by Oxytocin
24
Q

Stages of labour.

A

Stage 1: Contractions and cervical dilation
Stage 2: Foetal Expulsion
Stage 3: Placental Expulsion

25
Q

Regulation of parturition

A

Foetal stress stimulates release of cortisol (from foetus)
\/
prostaglandins and oestrogen> oxytocin
\/
Myometrial contractions increase and Cervical softening luteolysis
\/
Pressure increase
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cervical stimulation
\/
oxytocin> Myometrial contractions increase

26
Q

Myometrium

A

consists of non-striated smooth muscle fibres with gap junctions to create a syncytium

• Muscle cell hypertrophy x10 during pregnancy under influence of oestrogen

27
Q

Two hormones directly regulate myometrial contraction

A
  • Oxytocin Lowers the excitation threshold of muscle cells

* Prostaglandins Stimulates liberation of Calcium ions from intracellular stores

28
Q

Brachystasis

A

fibres contract but remain shortened on relaxation gradually shortening the uterus

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