Mammalogy Exam 2 - Topic 9 reproduction

What are the main components of the male reproductive system in mammals?

Paired testes, accessory sex glands, ducts, and an intromittent organ.

What is the function of the testes in male mammals?

Production of male gametes through spermatogenesis and male sex hormones.

What are seminiferous tubules?

Microscopic tubules in the testes lined by gametogenic tissue where spermatogenesis occurs.

What are Leydig Cells?

Clusters of endocrine cells between seminiferous tubules that produce male sex hormones.

Where do the testes develop in mammals?

In the pelvic cavity, usually descending into the scrotum through the inguinal canal.

What is the scrotum?

A fold of skin that houses the testes, varying in presence among different mammals.

How do the testes behave in some mammals during the breeding season?

They descend into the scrotum before the breeding season and retract back into the pelvis afterward.

What is the male duct system responsible for?

Carrying sperm from the testes to the exterior.

What is the pathway of sperm in the male duct system?

From seminiferous tubules to rete testis, then to epididymis, spermatic duct, and urethra.

What are the three portions of the urethra in eutherian mammals?

Prostatic urethra, membranous urethra, and spongy/penile urethra.

What do accessory sex glands produce?

Secretions that form seminal fluid, providing nutrients and a medium for sperm.

What is the function of seminal vesicles in mammals?

They typically produce the bulk of seminal fluid.

What is a copulatory plug?

A coagulated ejaculate that prevents other males from inseminating the female.

What is the primary intromittent organ in mammals?

The penis.

How does the structure of the penis differ between monotremes and therian mammals?

Monotreme penis is a thickening of the cloaca; therian penis arises from a genital tubercle.

What are the three tissue masses that compose the therian penis?

Corpora cavernosa (two) and corpus spongiosum (one).

What is the os penis or baculum?

A bone associated with the penis found in many eutherian mammals.

What is the female reproductive system composed of?

Paired ovaries, paired oviducts, a uterus, a vagina, and accessory structures.

What do the ovaries produce in female mammals?

Eggs/ova and female sex hormones.

How do monotreme ovaries differ from those of therian mammals?

Monotreme ovaries contain fluid-filled sacs called lacunae, and only one ovary is functional.

What is the germinal epithelium?

The outer covering of the ovaries in marsupial and placental mammals.

What are follicles in the ovaries?

Cellular structures composed of one immature ovum surrounded by epithelial cells.

What is the innermost zone of the ovary called?

The medulla, composed of well-vascularized loose connective tissue.

What is the outer zone of the ovary called and what does it contain?

The cortex, which contains follicles.

What are follicles composed of?

One immature ovum surrounded by epithelial cells.

What hormone stimulates the maturation of ovarian follicles?

Follicle Stimulating Hormone (FSH).

What is the Graafian Follicle?

The follicular stage that ovulates, releasing the ovum and surrounding epithelial cells.

What triggers ovulation?

Luteinizing Hormone (LH).

What is the Corpus Luteum and what does it secrete?

An endocrine structure formed from Graafian follicle cells that secretes Progesterone.

What is spontaneous ovulation?

Ovulation that occurs without copulation, influenced by hormonal and environmental factors.

What is induced ovulation?

Ovulation triggered by some portion of the mating act.

Give an example of a species that practices induced ovulation.

Domesticated swine, where the boar's grunting triggers ovulation.

What is the Estrous Cycle?

The cycle during which a female is receptive to mating, occurring around ovulation.

What are monoestrous species?

Species that breed only once per year.

What are polyestrous species?

Species that can breed multiple times per year.

What are the four phases of the estrous cycle?

Anestrus, Proestrus, Estrus, and Metestrus.

What occurs during the Anestrus phase?

A quiescent period when the animal is not receptive to breeding.

What happens during the Proestrus phase?

Follicles are stimulated to mature, the uterus swells, and the vagina enlarges.

What is Estrus?

The period of sexual receptivity in females.

What is Metestrus?

The phase following estrus where the corpus luteum maintains the uterine lining if fertilization occurs.

What is the difference between the estrous cycle and the menstrual cycle?

In the menstrual cycle, the uterine lining sloughs off if fertilization does not occur, rather than being reabsorbed.

What are the Muellerian ducts?

Embryonic structures that give rise to the female duct system in mammals.

What is the function of the oviducts?

To convey the egg from the ovary to the uterus.

What are the three segments of the oviduct?

Infundibulum, Ampulla, and Isthmus.

What is a Duplex Uterus?

A condition in marsupials where there are two completely separated uteri.

What is a Bicornuate Uterus?

A uterus with two cornua connecting to a uterine body, common in some mammals.

What is a Simplex Uterus?

A uterus that lacks cornua, typical in humans.

What are the three tunics of the uterine wall?

Perimetrium (outer), Myometrium (middle), and Endometrium (innermost).

What are the two layers of the Endometrium?

Stratum Basalis (permanent layer) and Stratum Functionalis (variable layer).

What is the Stratum Functionalis?

A highly variable mucosa that increases and decreases in thickness due to reproductive state.

What is the function of the vagina in eutherian mammals?

It is a hollow, muscular tube running from the uterus to the urogenital vestibule or sinus.

What occurs during gestation in therian mammals?

A fertilized egg implants on the thickened endometrium after the zygote undergoes cleavage.

What is the Morula stage?

A hollow sphere stage of the embryo that typically enters the uterus.

What is the Blastocyst stage?

A hollow sphere of cells with an internal mass (Inner Cell Mass) that will become the embryo.

What is the Trophoblast?

The outer sphere of cells in the blastocyst that will grow into the stratum functionalis and form the placenta.

What is the placenta's role?

It is a complex organ that attaches the developing offspring to the uterus, providing nourishment and oxygen while removing wastes.

What are Chorionic Villi?

Finger-like structures that grow from the embryonic portion of the placenta into the endometrium.

What type of placenta do marsupials produce?

The Choriovitelline Placenta, which is less thick and extensive than placental mammals' placentas.

How do marsupials receive nutrition during early development?

Through a large yolk sac and a nutrient-rich fluid called Uterine Milk from the endometrium.

What is the Chorioallantoic Placenta?

A thick, complex placenta produced by eutherians that provides for the offspring's metabolic needs.

What are the four types of eutherian placentas based on villi distribution?

Diffuse, Cotyledonary, Zonary, and Discoidal.

What characterizes a Diffuse Placenta?

Villi are evenly scattered throughout the uterus.

What characterizes a Cotyledonary Placenta?

Evenly spaced patches of placental villi penetrate the uterus.

What characterizes a Zonary Placenta?

A continuous band of villi penetrates the uterus.

What characterizes a Discoidal Placenta?

Villi are arranged into one or two disc-shaped areas penetrating the uterus.

What is the difference between Altricial and Precocial offspring?

Altricial offspring are born helpless and underdeveloped, while Precocial offspring are born fully developed and able to walk.

What is the gestation period like for marsupials?

Marsupials have very short gestation periods and give birth to less developed young.

What is Embryonic Diapause?

A reproductive strategy where the blastocyst enters a period of dormancy until a signal from the mother prompts development.

What is Delayed Implantation?

A reproductive strategy where development stops at the blastocyst stage until conditions improve.

What is the significance of delayed fertilization in some mammals?

Sperm is stored in the female reproductive tract until eggs are released, often found in hibernating species.

What is the role of Uterine Milk in marsupials?

It nourishes the developing embryo after birth until it can find a nipple.

How does the gestation period vary among eutherians?

It varies according to taxonomic group, body mass, litter size, and degree of development at birth.

What is the longest gestation period among mammals?

Found in elephants, lasting up to 22 months.