Repro Exam 3

Embryonic losses total

less than 5%

80% of pregnancy loss happens when?

before day 17 of gestation

10-15% of pregnancy loss happens when?

between day 17 and day 42

5% of pregnancy loss happens when?

After day 42

Why does the chances of losing a pregnancy drop around day 42?

The placenta is forming and attaching which allows the fetus to have more nutrients. CL and placenta producing progesterone. This is the end of the embryo stage.

When is the end of the embryo stage and what happens?

Around day 42. The placenta forms and attaches.

Preg check for mares

Ultrasound at 14 days after insemination. Reactal palpation at 35 days. Heartbeat around 45 days.

average length of survival of spermatozoa in cattle

24-48 hrs

average length of survival of spermatozoa in Horses

72-120hrs

average length of survival of spermatozoa in

30-48hrs

average length of survival of spermatozoa in hogs

24-48 hrs

average length of survival of ova in cattle

8-12 hrs

average length of survival of ova in horses

6-8hrs

average length of survival of ova in sheep

16-24 hrs

average length of survival of ova in sows

8-10hrs

Length of gestation in Cattle

279 days

length of gestation in horses

340 days

length of gestation in sheep

145 days

Length of gestation in goats

150 days

Length of gestation in swine

114 days

When is placentation usually completed in mares?

50-60 days

When is placentation usually completed in cows?

42 days

Functions of amniotic fluid

1. Protection and development without distortion

2. Prevents adhesion - fetal skin to membranes

3. Lubrication - parturition

Endoderm develops what?

Digestive system, lungs, most glands (thyroid)

Mesoderm develops what?

Skeletal system, reproductive system, circulatory system

Ectoderm develops what?

Skin, Hair, Sweat glands, hooves

Three stages of gestation

Stage of ovum or zygote: day 0 to 12

Embryo Stage: day 12-45

Fetal Stage: after day 45

What happens in the ovum/zygote stage?

Begins - fertilization is complete

Cleavage - cellular division without growth

Zygotes - enters uterus (16 to 32 cell stage - ZP intact)

ZP restricts change in size

Morula - 16 to 64 cell stage

Blastocyst - cavity forms

Basically: Zygote forms into Morula forms into Blastocyst

What happens in the embryo stage?

Gastrulation - differentiation - 3 germ cell layers

Formation of extra-embryonic membranes (placenta)

Amnion -amniotic fluid - amniotic sac

allantoic - allantoic fluid

Chorion - encloses embryo and membranes, attaches epithelium of uterus

Fetal vessels - form umbilical cord

Placenation or implantation

Basically: Gastrulation, formation of extra-embryonic membranes, chorion, umbilical cord, and placentation/implanation

What happens in the fetal stage?

embryo turns into fetus when essential organs form

further development and growth of fetus

maternal recognition of pregnancy

Zygote

a single diploid cell formed when sperm and egg unite

Blastocyst

An early embryo containing a build filled cavity and differentiated cell groups

Cleavage

Rapid mitotic cell divisions of zygote without overall growth in size

Gastrulation

The state when the three germ layers form: ectoderm. mesoderm, and endoderm

Morula

A solid ball of cells formed after several cleavage divisions

Syngamy

Fusio of the male and female pronuclei to form one nucleus

Vitelline block

A mechanism that prevents more than one sperm from fertilizing the ovum

Capacitation

Final changes sperm undergo in the female reproductive tract the make them capable of fertilizing the egg

Placentation

Formation and development of the placenta for exchange between mother and fetus

Three different layers of placenta

Amnion - surrounds the fetus and contains amniotic fluid

Chorion - outer membrane the forms the fetal part of the placenta

Allantois - involved in wast exchange and forms blood vessels that connect to the chorion

Which placental layer comes first?

Chorion

(Then amnion, then allantois)

Ultrasounding cows

• Detects pregnancy estimates stage of gestation, and identify structures (follicles, CL, embryo)

• Ultrasound is performed transrectally (probe goes into rectum)

• Pregnancy can be detected in cows around 25-30 days

• An ultrasound helps you see Follicular waves (follicles growing), ovulation (CL formation), and gestation stages (embryo/fetus development)

What hormone does the corpus lupium (CL) produce?

Progesterone

What hormone resist and grows follicles

FSH and LH

What is the structure in the mare that keeps the placocyst round longer than the other species?

Embryonic Capsule

When is plantation in does

day 20-22 (starts)

Day 40-45 (complete)

When is plantation in mares

Day 35-40 (starts)

Day 120 (complete)

Oogonium

Diploid

Zygote

Diploid

Primary oocyte

Diploid

Secondary oocyte

Haploid

T/F: Primary follicles are comprised of a primary oocyte surrounded by two or more layers of granulosa

False

T/F: A secondary follicle is a mature, ovulating follicle

False

T/F: Follicle stimulating hormone (FSH) is the hormone responsible for causing follicular recruitment

True

T/F: A primary follicle become a secondary follicle when an atrium is present

False

T/F: Primary and secondary follicles are visible on the surface of the ovarium

False

T/F: cows typically have two follicular waves during estrous cycle

True

T/F: Secondary oocyte are haploid in terms of chromosomal number

True

T/F: Secondary locates are present in most females at birth

False

T/F: Luteinizing hormone (LH) is the hormone responsible for causing ovulation of ovarian follicles

True

T/F: The lack of progesterone is directly involved with ovulation

True

T/F: Farm animals are induced ovulations

False

T/F: A Graffian follicle is a mature, ovulating follicle

True

List the two hormones that work together to cause follicular growth and maturation

FSH/LH