Reproductive System Female Anatomy and Hormones 11-Nov-18 Reproductive System Female Anatomy and Hormones

Female Anatomy and Hormones The vulva is the external opening to the urogenital tract Leads to the vagina Urine exits through the urethra into the caudal vagina and then the vuvla

Female Anatomy and Hormones The vagina then leads to the cervix A firm structure that protects the opening of the uterus During birth and “heat” the cervix can “open”

Female Anatomy and Hormones The uterus Has a short body the joins the two horns of the uterus It is “Y” shaped A hallow muscular walled organ line with epithelium that can expand dramatically to support the developing fetus

Female Anatomy and Hormones The uterine horns branch into smaller tubes called the oviduct or fallopian tubes These tubes lead to the ovaries At the end of these tubes is a thin membranous tissue called the infundibulum Wraps around the ovary to catch the released ovum

Female Anatomy and Hormones The ovaries are located caudally to the kidneys Has a large blood supply to keep the system working properly and to support embryo growth

Female Anatomy and Hormones Ovaries produce ovum (eggs) through meiosis during embryo development Precursor cells undergo the first step of meiosis then stop The number is limited but is a larger supply then what she will use in her lifetime Males: undergo mitosis of the precursor cells daily!

Female Anatomy and Hormones Estrous versus Estrus Estrous cycle: Begins at puberty (sexual maturity) Prepares a female to become pregnant Cycles but varies by species All controlled by hormones produces by the reproductive and endocrine system Estrus: Time of sexual receptiveness “Heat” Tells the male that the female is receptive to breeding Varies in length by species

Female Anatomy and Hormones Terms to Know: Polyestrous: Continue to cycle until they become bred Seasonally Polyestrous: Cycle only during certain times of the year Anestrous: Not cycling (Milking)

Female Anatomy and Hormones Estrous is divided into 4 phases Hormones released during these phases differ greatly Proestrus Estrus Metaestrus Diestrus

Female Anatomy and Hormones Proestrus Timing: approx 3 days before heat Prostaglandin is released by the uterus into the bloodstream Ovary contains a corpus luteum (CL) that produces progesterone Prostaglandin causes the CL to regress lowering the levels of progesterone in the blood stream

Female Anatomy and Hormones Proestrus Declining Progesterone cause the pituitary gland to secrete FSH and LH Higher FSH causes the ovaries to develop a follicle –fluid filled sac around the egg The follicle releases estrogen in response to the FSH Estrogen is what is responsible for behavioral changes in the female prior to heat.

Female Anatomy and Hormones Proestrus LH rates increase the day prior to estrus

Female Anatomy and Hormones Estrus Short period of time: 8-30 hours – most tend to cycle short Signs of Estrus: Standing to be bred Mounting Bellowing Restlessness Excitability Mucus discharge Reddish and swollen vuvla

Female Anatomy and Hormones Estrus Follicle releases the egg 10-14 hours after onset of estrus Ovulation - Marks day 1 of the estrous cycle Infundibulum catches the egg and transports it to the oviduct If animal has been bred, sperm should be present in the fallopian tubes to fertilize the eggs (fertilization) Follicle collapses after ovulation- leaving a mark on the ovary

Female Anatomy and Hormones Metestrus Follows ovulation: lasts 3-4 days Estrogen declines and LH causes the former follicle to create a Corpus Luteum (CL) – CL produces progesterone Stimulates the uterus to prepare to nourish the embryo The embryo continues to travel down the fallopian tubes towards the uterus

Female Anatomy and Hormones Diestrus (if pregnant) Embryo moves into the uterus and implants (conception) CL produces large amounts of progesterone to stimulate the growth of the lining of the uterus If pregnant, the uterus will not release prostaglandin and the CL will not regress Progesterone is essential to maintaining the pregnancy

Female Anatomy and Hormones Diestrus – (If open) Lasts 12-15 days Without pregnancy the uterus will release prostaglandin and the animal will renter proestrus

Show Me What You Know… With a partner…create a “cycle” chart that shows what occurs during estrous Must be included: 4 Stages of Estrous Hormones Where these hormones are created Be creative when making this chart! 50 Points will be given for this assignment – Most creative will earn 25 extra bonus points!