ANSC 110 Chapter 10 Study Guide

ANSC 110 Intro to Animal Science

Oviducts (Fallopian tubes)

Site of fertilization.

Uterus

That portion of the female reproductive tract where the young develop during pregnancy.

Cervix

The portion of the female reproductive tract between the vagina and the uterus. It is usually sealed by thick mucus except when the female is in estrus or delivering young.

Ovaries

Suspended by ligaments just caudal of the kidneys, and a pair of open-ended tubes.

Follicle

A blisterlike, fluid-filled structure in the ovary that contains the egg.

Graafian Follicle

Mature follicle capable of ovulating.

Corpus Luteum

A yellowish body in the mammalian ovary. The cells where follicular cells develop into the corpus luteum, which secretes progesterone. It becomes yellow in color from the yellow lipids that are in the cells.

Infundibulum

Fingerlike projections of the oviduct that “catch” the egg upon ovulation.

Parturition

The process of giving birth.

Cloaca

Portion of the lower end of the avian digestive tract that provides a passageway for products of the urinary, digestive, and reproductive tracts.

Magnum

Portion of the avian oviduct that secretes the albumen or white of the egg.

Isthmus

Portion of the avian oviduct that secretes the shell membranes.

Testicles

The male sex gland that produces sperm and testosterone.

Sperm

Gamete produced by males.

Seminiferous Tubules

Minute tubules in the testicles in which sperm are produced. They comprise about 90% of the mass of the testes.

Epididymis

The long, coiled tubule leading from the testis to the vas deferens.

Vas Deferens

Ducts that carry sperm from the epididymis to the urethra.

Ductus Deferens

Also known as the vas deferens, responsible for sperm transport.

Ampulla

The dilated or enlarged upper portion of the vas deferens in bulls, bucks, and rams, where sperms are stored for sudden release at ejaculation.

Interstitial Cells (Leydig cells)

The cells between the seminiferous tubules of the testicle that produce testosterone.

Testosterone

The male sex hormone that stimulates the accessory sex glands, causes the male sex drive, and causes the development of masculine characteristics.

Accessory Sex Glands

Responsible for adding nutrients and fluid volume to semen.

Glans Penis

Free end of the penis.

Luteinizing Hormone (LH)

A protein hormone, produced and released by the anterior pituitary, which stimulates the formation and retention of the corpus luteum. It also initiates ovulation.

Follicle-Stimulating Hormone (FSH)

A hormone produced and released by the anterior pituitary that stimulates the development of the follicle in the ovary.

Gonadotropin-Releasing Hormone (GnRH)

Stimulates release of LH and FSH.

Prostaglandin

Chemical mediators that control many physiological and biochemical functions in the body. One prostaglandin (PGF 2a) can be used by synchronize estrus.

Estrogen

Any hormone (including estradiol, estriol, and estrone) that causes the female to come physiologically into heat and to be receptive to the male. Estrogens are produced by the follicle of the ovary and by the placenta.

Estrous Cycle

The length of time between heats.

Estrus (Heat)

The period of mating activity in the female mammal. Same as heat.

Prostaglandin

Chemical mediators that control many physiological and biochemical function in the body. One prostaglandin (PGF 2a) can be used to synchronize estrus.

Oxytocin

Can be given to speed the rate of delivery

Conceptus

Embryo and embryonic membranes taken in total.

Embryonic Stage

The early developmental period that begins after a sperm fertilizes an egg.

Fetus

Later stage of individual development within the uterus. Generally, the new individual is regarded as an embryo during the first half of pregnancy, and as a fetus during the last half.

Placenta

The vascular organ that unites the fetus to the uterus.

Placentation

Period of attachment.

Diffuse

Type of chorionic attachment in mares and sows, characterized by uniform villi attachment across the membrane.

Cotyledonary

Type of chorionic attachment in cows, ewes, and does, characterized by specialized sites of attachment.

Placentomes

Specific structures of cotyledonary attachment.

Caruncle

The “buttons” on the ruminant uterus where the cotyledons on the fetal membranes attach.

Cotyledon

An area of the placenta that contacts the uterine lining to allow nutrients and wastes to pass from the mother to the developing young. Sometimes referred to as button.

Parturition

The process of giving birth.

The female poultry has two ovaries and two oviducts. The right ovary and oviduct do not develop. A sexually mature hen has a well-developed ovary and oviduct only on the left side. The oviduct is a long, glandular tube leading from the ovary to the cloaca (common opening for reproductive and digestive tracts). The oviduct is divided into five part: (1) the infundibulum which receives the yolk; (2) the magnum which secretes the thick albumen, or white, of the egg; (3) the isthmus which adds the shell membranes; (4) the uterus or shell gland, which secretes the thin white albumen, the shell, and the shell pigment; and (5) the vagina.

The male poultry testes are contained in the body cavity. Each vas deferens opens into small papillae, which are located in the cloacal wall. The ale fowl has no penis but does have a rudimentary organ of copulation. The sperm are transferred from the papillae to the rudimentary copulatory organ, which transfers the sperm to the oviduct of the hen during the mating process. The sperm are stored in primary sperm-host glands located in the oviduct. These sperm are then released on a daily basis and transported to secondary storage glands in the infundibulum.

Describe the primary reproductive organs and their functions in male and female livestock and poultry.

Gonadotropin-releasing hormone (GnRH) – Release of LH and FSH.

Luteinizing hormone (LH) – Ovulation CL formation progesterone production and testosterone production.

Follicle-stimulating hormone (FSH) – Development of follicle, estrogen synthesis, and sperm production.

Prolactin – Milk synthesis and maternal behavior.

Oxytocin – Gamete transport, uterine contraction, and milk let down.

Estrogen – Mating behavior, uterine growth, secondary sex characteristics, and promotes GnRH release.

Progesterone – Maintains pregnancy, mammary development, and inhibits GnRH release.

Testosterone – Anabolic growth, sperm production, secondary sex characteristics.

 Prostaglandin F2a – Regression of CL, uterine contraction, and ovulation.

Placental lactogen – Promotes lactation.

Relaxin – Cervical dilation and pelvic expansion.

Cortisol (fetal) – Initiation of parturition.

Melatonin – Partial control of seasonal reproductive patterns. 

List the hormones and their roles in regulating reproductive function.

The estrous cycles is the length of time between heats. These patterns are of three types based on the timing and frequency throughout the year: polyestrous, seasonally polyestrus, and monostrus. The estrous cycle can be further broken down into four stages – proestrus and estrus (follicular phase) and metestrus and diestrus (luteal phase).

Describe the estrous cycle and define its phases/stages.

Polyestrus – cattle and swine.

Seasonal polyestrus – sheep, goats and horses.

Monoestrus – dogs.

Identify which species demonstrate the following estrous cycles:

Heifer, cow (cattle) – 6-18 months

Ewe (sheep) – 6-12 months

Mare (horse) – 20 months

Gilt, sow (swine) – 5-10 months

Doe (goat) – 4-8 months

Heifer, cow (bison) – 24 months.

Compare and contrast age at puberty for the primary livestock species.

Heifer, cow (cattle) – 14-29 days

Ewe (sheep) – 14-19 days

Mare (horse) – 19-24 days

Gilt, sow (swine) – 19-23 days

Doe (goat) – 18-22 days

Heifer, cow (bison) – 18-22 days

Compare and contrast length of estrous cycles for the primary livestock species.

Heifer, cow (cattle) – 12-30 hours

Ewe (sheep) – 24-36 hours

Mare (horse) – 4-8 days

Gilt, sow (swine) – 2-3 days

Doe (goat) – 1-3 days

Heifer, cow (bison) –

Compare and contrast duration of estrus for the primary livestock species.

Heifer, cow (cattle) – 18-48 hours

Ewe (sheep) – 24-27 hours

Mare (horse) – 24-48 hours prior to end of heat  

Gilt, sow (swine) – 38-42 hours

Doe (goat) – 24-36 hours

Heifer, cow (bison) – 18-45 hours

Compare and contrast the timing of ovulation for the primary livestock species.

Seasonal species are responsive to melatonin, a hormone produced by the pineal gland in response to declining periods of light. Thus, the mare’s estrous cycle is stimulated by decreasing periods of dark that results in declining levels of melatonin secretion resulting in increased GnRH secretion and thus initiation of the ovulatory cascade. Conversely, increased levels of melatonin resulting from the increasing levels of darkness in the fall moths stimulate the ewe.

Describe the effects of seasonal factors and the role(s) of melatonin on reproduction.

A process called maternal recognition of pregnancy signals the presence of the embryo and allows attachment to the uterus. The signal is sent via a system of recognition factors and if not complete within approximately 2 weeks for farm animals, termination of the pregnancy will result.

Describe the structures that establish and maintain pregnancy.

Cow (cattle) – 285 days, cotyledonary, 1

Ewe (sheep) – 147 days, cotyledonary, 1-3

Mare (horse) – 336 days, diffuse, 1

Sow (swine) – 114 days, diffuse, 6-14

Doe (goat) – 150 days, cotyledonary, 2-3

Cow (bison) – 270 days, cotyledonary 1

Compare and contrast gestation length, placentation, and normal fetal number for livestock.

The parturition process is initiated by release of the hormone cortisol from the fetal adrenal cortex. Progesterone levels decline, whereas estrogen, prostaglandin F2a, and oxytocin levels rise, resulting in uterine contractions.

Describe the process of normal parturition.

The front feet extend with the head between them.

Describe the fetal position in a normal parturition.