Female Reproduction
- Reproductive failure originates from ovary
Structures and functions-
- Ovary; primary sex organ that produces ova (eggs) and the hormone, estrogen, and progesterone
o Follicle – a mature follicle is called a Graafian follicle
o Ovulation – follicle ruptures and releases egg
o Corpus hemorrhagicum – site formerly occupied by the ovum is filled with blood
o Corpus lutenum (yellow body) – if pregnant, corpus hemorrhagicum is filled with cells and produces a corpus lutenum to secrete progesterone to maintain pregnancy
o Corpus albicans (white body) – if pregnancy DOES NOT occur, the corpus lutenum regresses to form a corpus albicans
- Oviducts (Fallopian Tubes); site of fertilization
o Infundibulum – funnel to pick up ovulated eggs
o Ampulla
o Isthmus
- Uterus (womb); site of placental, embryonic and fetal development
o Produces hormones prostaglandin-F2-a (alpha)
o vascular
§ Horns – 2
§ Body
- Cervix; cartilaginous organ that connects uterus to vagina
o During estrus, the cervix is moist and open
§ Only during estrus will it open and fill with fluid
o During pregnancy, cervix is sealed
o Rigid and able to seal
- Vagina; copulatory organ of female, birth canal, bladder also opens into vagina
- Clitoris; highly sensitive organ at the lower tip of vagina
o Homologous to penis in male
o Stimulation of clitoris after AI my increase conception rate
- Vulva; external genitilia
o Homologous to scrotum in male
Additional Notes:
- Ovary
o where the egg comes from
- All of the eggs you are born with, that’s it (they DO NOT regenerate)
- All contained in a follicle (pool of eggs waiting to be released)
o Released by hormonal events (developmental, production)
o Single celled line structure that contains egg
o Follicle is like a blister – fluid filled
§ When it grows, it ruptures (ovulation)
· Ruptures and exits ovary
o Ruptures follicle, wound on ovary (Corpus hemorrhagicum – bloody body)
o Grow and fill with yellow tissue (yellow body - Corpus lutenum)
§ Secretes progesterone
§ If they don’t become pregnant, it dies
§ ONLY responds in response to a hormone
§ IF it dies, doesn’t produce progesterone
o When season is right, animal will cycle
§ When season ends, cycle ends as well
o If you don’t CL or progesterone, pregnancy doesn’t carry out
- Progesterone is key hormone and estrous cycle
- Ovary is not functional because the start signal is not received due to not meeting requirements such as nutritional status
- Ovary surrounded by tissue to catch an egg (like a funnel)
- Infundibulum (funnel)
o Goes to the oviduct (egg passage)
- Sperm contact eggs and fertilize = embryo
o Embryo floats for some time (various days)
- If attached to uterus, you CANNOT flush it out
- If not attached, it can be flushed out and placed into another female
Secondary Characteristics
- Physical features; femininity
- Relation to hormone production
Hormones
- Gonadotropin releasing hormone (GnRH) – produced in hypothalamus
o Stimulates LH and FSH release
o Produced in hypothalamus
- Pituitary hormones
o Follicle stimulating hormone (FSH) – produced by anterior pituitary gland
§ Stimulates growth of follicles on ovary
o Luteinizing hormone (LH) – produced by anterior pituitary
§ Causes Graafian follicle to rupture (ovulation) and corpus lutenum to form
o Prolactin – produced by anterior pituitary
§ Initiates and maintains lactation (milk production)
o Oxytocin – produced by posterior pituitary
§ Stimulates uterine contractions and milk letdown in mammals
· Ex; uterine contractions and egg laying
- Gonadal
o Estrogen – produced from follicle on ovary
§ Responsible for development of secondary sex characteristics and general appearance
· Ex; finer hair, feminine voices, manners, and body contours different from males
§ Also duct growth in mammary glands, estrus or heat period when female is receptive to mating, prepares uterus for pregnancy, increases motility of uterus and oviducts during estrus
o Progesterone – produced by corpus lutenum
§ Prevents ovulation and maintains pregnancy
§ Functions to increase development of milk producing tissues in udder
o Relaxin – produced by ovaries or placenta
§ Causes relaxation of cartilage and ligaments in pelvis to assist parturition
Fertilization:
- Insemination
- Ovulation
- Site
- Transports of gametes
- Effect on reproductive efficiency
Implantation of embryo and fetal development:
- Site
- Nourishment
o Transfer of nutrients from mother to young
o Transfer of wastes from young to mother (morning sickness)
- Placenta; diffuse (mare and sow) cotyledonary (cow and ewe)
o Function as transmission of nutrients from mother to young
o Protection from shock
o Prevents transmission of microbes
o Prevention of transmission of bacteria
Parturition
- Normal fetal position is front legs and head facing toward rectum
- Heifers are at risk for more problems than a mature cow
Advances in Reproduction:
- Artificial insemination
- Estrous synchronization
- Superovulation
- In vitro fertilization (test tube babies)
- Embryo transfer
- Freezing embryos
Additional Notes:
- Uterine contractions stimulated by oxytocin to push out fetus
- Estrus – event during cycle (heat)
- Estrous- hormone level changes during cycle (days)
- Cotyledons, almost like a pepperoni (the more there is, the better)
- Placenta (after birth) should be passed within 12 hours after birth
o More important for horses to do so because they can get sick and die
- Puberty; when animal is able to reproduce
- FSH – causes follicles to grow in ovary
- Access through rectum to access reproductive tract (rectum palpitation)