Wk 6 Vocab Reproductive Flashcards
Acrosome
The caplike structure that partially covers the head of
a spermatozoon. It contains digestive enzymes that are activated
when the sperm enter the female reproductive tract. These
help the cell penetrate through the layers around the ovum to fertilize it.
Afterbirth
The name given to the placenta at parturition because
it is delivered after the newborn.
Allantoic sac
Part of the placenta. It is a fluid-filled sac formed
by the allantois that surrounds the amniotic sac.
allantois
Part of the placenta. It is the membrane that forms the
allantoic sac
Alveolar duct
The smallest air passageways in the lungs. The
alveolar ducts carry air to the alveolar sacs.
Alveoli
Microscopic, thin-walled sacs surrounded by networks of capillaries. The interface between the
wall of the alveoli and the wall of the capillary is where the actual
exchange of gases takes place in the lungs.
Amnion
Part of the placenta. It is the membrane that forms the
fluid-filled amniotic sac.
Ampulla
An enlargement in each semicircular canal that contains
the receptor structure (the crista).
Amniotic sac
Part of the placenta. It is the fluid-filled sac that
immediately surrounds the developing fetus.
Androgen
Hormones that promote the development of male
characteristics; male sex hormones. The principal androgen is
testosterone.
Antibody
Proteins produced by plasma cells (transformed B
lymphocytes) in response to the presence of an antigen. A specific serum antibody is generated for a specific antigen
Antrum
(1) The fluid-filled space within an ovarian follicle. (2)
The muscular part of the stomach that is responsible for grinding of food; located between the body of the stomach and the
pylorus.
blastocyst
The stage of development of a zygote that is ready for
implantation in the uterus. It is shaped like a tiny, hollow ball
of cells with a “bump” on one side that eventually develops into
the embryo
body of the penis
The largest portion of the penis. It contains
the majority of the erectile tissue of the organ.
broad ligaments
Paired sheets of connective tissue that suspend
the uterus from the dorsal part of the abdominal cavity and
attach it to the abdominal wall. They are often subdivided into
the mesovarium, which supports the ovary; the mesosalpinx,
which supports the oviduct; and the mesometrium, which supports the uterus.
bulb of the glans
An enlargement in the penis of the dog and
related species. It is made up of erectile tissue that slowly
engorges with blood during copulation. When muscles surrounding the vagina and vulva of the female clamp down on the
enlarged bulb, the male cannot withdraw the penis. He typically
dismounts and turns so that the two animals are tail to tail. This
position is known as the tie and usually lasts 15 to 20 minutes,
after which the animals can separate.
bulbourethral glands
Male accessory reproductive glands that
secrete a mucus-containing fluid just before ejaculation that
lubricates the urethra for the passage of semen and clears it of
urine. Bulbourethral glands are present in all common domestic
animals except dogs.
capacitation
The process spermatozoa undergo in the female
reproductive tract that increases their fertility before contact
with the ovum. Part of the process exposes the digestive enzymes
in the acrosome. This helps the cell penetrate through the layers
surrounding the ovum.
caruncle
Numerous mushroomlike structures in the lining of the
uterus of ruminant animals. They join with the cotyledons of
the placenta to form placental attachment sites called
placentomes.
cervix
The sphincter muscle “valve” between the uterus and the
vagina; controls access to the lumen of the uterus from the vagina.
It is normally closed except during breeding and parturition.
chorion
Part of the placenta; the outermost layer that attaches to
the uterine lining. The chorion is linked to the fetus by the
umbilical cord.
chromosome
Threadlike accumulations of DNA in the nuclei
of cells that are particularly visible during mitosis. The DNA of
the chromosomes contains the genetic material of the cell. The
number of chromosomes is constant within a given species
cleavage
The process of very rapid cell division after an ovum
has been fertilized. The cells divide so rapidly that they do not
have time to grow appreciably between divisions. The number
of cells increases rapidly, but the overall size of the cell mass does
not increase much.
clitoris
One of the structures of the vulva of the female. Homologous to the penis of the male, the clitoris contains erectile tissue
and is richly supplied with sensory nerve endings.
colostrum
The initial secretion of the mammary gland before
milk is produced. Colostrum is rich in nutrients, has a laxative
effect on the newborn, and contains antibodies to the diseases
the dam has been exposed to or vaccinated against. If the
newborn drinks the colostrum within the first few hours of
birth, the large antibody molecules will be absorbed intact by
the intestine and impart passive immunity to the young animal.
Common vaginal tunic
The outer connective tissue sac that surrounds the testis. It is derived from the layer of parietal peritoneum that was pushed ahead of the testis as it descended
through the inguinal ring. Also called the parietal vaginal tunic.
copulation
The act of breeding; consists of intromission of the
penis into the vagina, thrusting, and ejaculation.
cornification
formation of a layer of tough keratin on an epithelial surface
Corona glandis
The widest portion of the glans penis of
the horse.
corona radiata
A thin layer of granulosa cells that surrounds the ovum as it develops in the ovarian follicle and after it is released
by ovulation.
corpus cavernosum
penis
The larger of the two erectile tissue
structures in the body of the penis. It is located dorsal to the
smaller corpus cavernosum urethrae.
corpus cavernosum
urethrae
The smaller of the two erectile
tissue structures in the body of the penis. It forms a “sleeve”
around the urethra and is located ventral to the larger corpus
cavernosum penis.
corpus
hemorrhagicum
The blood-filled remnant of the ovarian
follicle immediately after ovulation.
corpus luteum
Literally “yellow body.”The solid endocrine structure that forms from the empty ovarian follicle after ovulation.
Under stimulation from luteinizing hormone from the anterior
pituitary gland, the granulosa cells left in the empty follicle
multiply to form the solid corpus luteum. It produces progestin
hormones, principally progesterone, that are necessary for the
maintenance of pregnancy
cotyledon
Numerous areas on the surface of the placenta of ruminant animals that join with the caruncles in the lining of the
uterus to form placental attachment sites called placentomes.
cotyledonary placental
attachment
The type of placental
attachment found in common ruminant animals. It consists of
numerous cotyledons on the surface of the placenta joining with
caruncles in the lining of the uterus to form attachment sites
called placentomes.
cremaster muscle
The bandlike muscle that raises and lowers the
testes in the scrotum to help control their temperature. The
testes must be maintained at a temperature slightly cooler than
body temperature to produce spermatozoa
crura
A portion of the roots of the penis. The connective tissue
bands that attach the penis to the brim of the pelvis.
cryptorchidism
The condition of one or both testes failing to
descend into the scrotum. Cryptorchidism in animals may be
unilateral (one side only) or bilateral (both sides).
cumulus oophorus
The small mound of granulosa cells on which
the oocyte sits as it develops in the ovarian follicle.
delivery of the
newborn
Passage of the newborn animal through
the vagina from the uterus to the outside world. Accomplished
by a combination of uterine and abdominal muscle
contractions.
delivery of the
placenta
Passage of the placenta through the
vagina from the uterus to the outside world after delivery of the
newborn. Accomplished by a combination of uterine and
abdominal muscle contractions.
retractor penis muscle
An elastic, bandlike muscle that pulls the
nonerect penis of animals with a sigmoid flexure back into its
S-shaped configuration.
roots of the penis
The structures that attach the penis to the
brim of the pelvis. They consist primarily of the two connective
tissue crura covered by the ischiocavernosus muscles.
round ligament of the
uterus
A cord of fibrous tissue and
smooth muscle contained in the free edge of a lateral fold of the
broad ligament in the female. Extends from the tip of the uterine
horn caudally and ventrally to the area of the inguinal ring.
scrotum
The sac of skin that houses the testes and, by raising or
lowering them, helps control their temperature.
seasonally
polyestrous
An animal that has continuous estrous
cycles during a certain portion, or portions, of the year and no
estrous cycles at other times.
seminal vesicle
Accessory reproductive glands that contribute
various materials to semen. Seminal vesicles are present in all
common domestic animals except the dog and cat.
seminiferous tubule
The site where spermatogenesis (spermatozoa production) takes place in the testis
sertoli cell
Large“nurse” cells which spermatozoa are attached
during their development. Sertoli cells normally produce small
amounts of estrogen hormones. If they grow abnormally and
form a Sertoli cell tumor, the unusually high amount of estrogens produced by the tumor can cause feminization of the
affected male animal.
sex chromosome
Two of the normal diploid chromosome
complement. The sex chromosomes determine the genetic sex
of the individual. If there are two X sex chromosomes, the individual is genetically female. If there is an X and a Y sex chromosome, the individual is genetically male.
sigmoid flexure
The S-shaped bend in the nonerect penis of the
bull, ram, and boar.
spermatic cord
Cordlike connective tissue structures that
enclose blood vessels, nerves, lymphatic vessels, and the vas
deferens as they pass between the testes and the abdominal
cavity through the inguinal rings.
spermatogenesis
The production of spermatozoa in the testis.
spermatic cord
Cordlike connective tissue structures that
enclose blood vessels, nerves, lymphatic vessels, and the vas
deferens as they pass between the testes and the abdominal
cavity through the inguinal rings.
spermatogenesis
The production of spermatozoa in the testis.
spermatozoon
(plural, spermatozoa) The male reproductive
cell. The male gamete.
diestrous
Animals that have two estrous cycles per year
diestrus
The active luteal stage of the estrous cycle. During this
period, the corpus luteum has reached maximum size and is
producing maximum amounts of progestin hormones.
diffuse placental
attachment
A loose form of placental attachment to the uterine wall; attachment sites are spread diffusively
over the whole surface of the placenta and the whole lining of
the uterus; found in horses, swine and camelids
Diploid chromosome number
The chromosome number in all
of an animal’s cells except for the gametes (reproductive cells).
It is always an even number
discoid placental
attachment
Attachment of the placenta to the
uterus in a single, disc-shaped area; found in primates, rabbits,
and many rodents.
Dystocia
A difficult birth. Dystocias usually result from a fetus
that is too large for the birth canal or one that is oriented inappropriately for delivery
efferent ducts of the
testes
The passageways that allow spermatozoa to move from the rete testis to the head of the
epididymis.
ejaculation
The reflex expulsion of semen from the penis.
embryo
The name generally given to the developing offspring
during the first trimester of pregnancy. During this period, the
newly implanted zygote and its placenta are getting themselves
organized and the body tissues, organs, and systems begin to
form
endometrium
the mucous membrane lining the uterus, which thickens during the menstrual cycle in preparation for possible implantation of an embryo
epididymis
The ribbonlike structure that lies along the surface
of the testis. It is actually one long, convoluted tube that links
the efferent ducts with the vas deferens. Spermatozoa are stored
in the epididymis as they await ejaculation.
erectile tissue
A spongy network of fibrous connective tissue and
blood sinuses. When more blood flows into erectile tissue than
leaves it, the sinuses engorge with blood and create hydraulic
pressure that enlarges and stiffens the organ in which the erectile
tissue is located.A spongy network of fibrous connective tissue and
blood sinuses. When more blood flows into erectile tissue than
leaves it, the sinuses engorge with blood and create hydraulic
pressure that enlarges and stiffens the organ in which the erectile
tissue is located.
erection
Enlargement and stiffening of an organ that contains
erectile tissue, such as the penis, clitoris, or nipple.
estrogen
Hormones that promote the development of female
characteristics; female sex hormones.
estrous
An adjective used with the noun “cycle” to refer to the
entire reproductive cycle in females.
estrous cycle
The period from the beginning of one heat period
to the beginning of the next. It includes the stages of proestrus,
estrus, metestrus, and diestrus.
estrus
The heat period; the stage of the estrous cycle when the
female is sexually receptive to the male and will allow breeding
to take place.
female pronucleus
The name for the nucleus of an ovum after the
head of a spermatozoon has penetrated into the cell (fertilization
of the ovum) but before the nuclei of the sperm (the male pronucleus) and ovum have come together. When the female and
male pronuclei combine, the diploid chromosome number is
restored and the genetic makeup of the offspring is determined.
fertilization
The physical entry of the head of a spermatozoon
into an ovum, which is then called a zygote. The nuclei of the
ovum and sperm merge, establishing the genetic makeup of the
future offspring.
fetal development
The second stage (trimester) of pregnancy
during which all the cells, tissues, organs, and systems of the
fetus develop from primitive, undifferentiated stem cells
fetal growth
The third stage (trimester) of pregnancy during
which all parts of the fetus grow in size and complexity to
prepare for the transition to a free-living, independent existence
after parturition (the birth process).
fetus
The name given to the developing offspring, beginning
about the second trimester of pregnancy. The body tissues,
organs, and systems develop in the early fetal period, and then
the offspring grows to its full birth size
fimbriae
The muscular, fingerlike projections that form the
fringe of the infundibulum of the oviduct. The fimbriae
feel their way across the surface of the ovary to where
follicles are developing. They help position the infundibulum so
that the ovum or ova will be guided into the oviduct when
ovulation occurs.
follicle
A fluid-filled structure or cavity. An ovarian follicle consists of an oocyte surrounded by fluid and the follicular cells
that produced it. Thyroid follicles are microscopic and consist
of small globules of thyroid hormone precursor surrounded by
simple cuboidal cells
follicular atresia
The shrinkage of ovarian follicles that began
developing but stopped.
follicular cell
The cells that surround oocytes in ovarian follicles. Also known as granulosa cells. They produce estrogenic
hormones in developing follicles.
fossa glandis
A shallow depression at the tip of horse’s penis
from which the urethral process protrudes.
gamete
A reproductive cell—spermatozoon in the male or ovum
in the female. Gametes have half the number of chromosomes
(the haploid chromosome number) present in all other body
cells (the diploid chromosome number).
gestation
The period of pregnancy
gland sinus
The large space in the mammary gland into which
the large milk ducts empty. It is located just dorsal to the teat.
glans of the penis
The distal, free end of the penis. It is richly
supplied with sensory nerve endings.
glycoprotein
A compound composed of a carbohydrate, usually
in the form of sugar, and a protein.
gonad
The organ that produces the reproductive cells; the testis
in the male and the ovary in the female.
granulosa cell
The follicular cells of the developing follicle.
They produce estrogenic hormones
gubernaculum
The short, inelastic band of connective tissue that
attaches the testes to the scrotum. Growth of the embryo, while
the gubernaculum stays the same length, results in movement
of the testes caudally and ventrally. Eventually, they descend
through the inguinal rings into the scrotum.
haploid chromosome
number
The chromosome number in the
gametes (reproductive cells). It is half the diploid chromosome
number that is present in all other body cells
haploid chromosome
number
The chromosome number in the
gametes (reproductive cells). It is half the diploid chromosome
number that is present in all other body cells.
homologous
Similar in basic structure and from the same
embryological origin. The penis of the male and the clitoris of
the female are homologous structures.
hydraulic pressure
Pressure exerted by confined fluids. During
erection of the penis, more blood enters the erectile tissue of the
penis than leaves it. The resulting hydraulic pressure produces
enlargement and stiffening of the penis.
implantation
Embedding of a developing blastocyst in the lining
of the uterus.
infundibulum
The funnel-shaped ovarian end of the oviduct.
Cilia lining the infundibulum beat rhythmically to ensure
passage of the ovum into the oviduct
inguinal ring
Slitlike openingsin the abdominal muscleslocated
in the groin (inguinal) region. The spermatic cords of the male
pass through the inguinal rings from the scrotum to the interior
of the abdominal cavity.
sphincter
A circular muscle that surrounds and controls
flow through an orifice.
streak canal
The passageway at the tip of the teat of the cow that
carries milk from the teat sinus outside the body.
stages of labor
The three main parts of the parturition (birth)
process. Stage 1 consists of uterine contractions that force the
membrane-covered fetus against the cervix, causing it to dilate.
Stage 2 is the delivery of the newborn animal by a combination
of uterine and abdominal muscle contraction. Stage 3 is delivery
of the placenta by a combination of uterine and abdominal
contractions.
suspensory ligament
of the ovary
The cranial edge of the broad
ligament in the female that extends cranially and dorsally from
the ovary and attaches to the body wall in the area of the last rib.
teat sinus
The large space within the teat of the cow that fills with
milk when milk let-down occurs.
testes
The male gonads. They produce the male reproductive
cells, spermatozoa, as well as androgen hormones.
tie
he process by which male and female dogs become temporarily “attached” to each other as a part of the breeding process.
Muscles in the female clamp down around the enlarged bulb of
the glans of the penis, making it impossible for the male to
withdraw the penis for a time. The male dismounts and turns
so that the two animals stand tail to tail. The tie lasts about 15
to 20 minutes and does not seem uncomfortable to either
animal
trimester
The three main divisions of pregnancy. They are not
equal thirds, but they give a convenient way to describe the
events occurring during pregnancy.
udder
The collected inguinal mammary glands. As of cattle,
horses, sheep, goats and camelids.
umbilical artery
The umbilical arteries carry deoxygenated blood from fetal circulation to the placenta.
umbilical cord
The link between the fetus and the placenta. It is
a cordlike structure that contains blood vessels and a drainage
tube from the urinary bladder of the fetus (the urachus).
umbilical vein
The vein in the umbilical cord that carries oxygen
and nutrient-rich blood from the placenta to the fetus.
uniparous
An animal that normally gives birth to only one offspring at parturition.
urachus
A tube in the umbilical cord that drains urine from the
fetus’s urinary bladder into the allantoic sac of the placenta.
urethra
The tube that connects the urinary bladder with the
outside world. In the female, it only conducts urine. In the male,
it conducts urine and semen.
interstitial cell
Endocrine cells located between the seminiferous
tubules of the testes. They produce androgens, the male sex
hormones
intromission
Insertion of the penis into the vagina.
involution of the
mammary gland
“Drying up”of the mammary
gland when the stimuli for lactation cease; the cessation of milk
production with shrinkage of the mammary gland back to near
its prelactation size.
involution of the
uterus
Shrinkage of the uterus after parturition
back to near its prepregnant size
labia
Literally means lips. The external boundary of the vulva of
the female.
lactation
Milk production by the mammary gland.
ligate
Surgically tied off, as with blood vessels; usually done
with suture material.
male pronucleus
The name for the nucleus of a spermatozoon
after its head has penetrated into the ovum (fertilization of
the ovum) but before the nuclei of the ovum (the female
pronucleus) and the sperm have come together. When the
female and male pronuclei combine, the diploid chromosome
number is restored and the genetic makeup of the offspring is
determined.
mastitis
Infection of a mammary gland.
mature follicle
An ovarian follicle that is fully developed and
ready for ovulation; also known as a vesicular follicle or a Graafian follicle.
meconium
Dark, tarry material in the intestine of a newborn
animal. The first feces passed by the newborn.
meiosis
The reduction division that reproductive cells undergo
during their development. It results in a reduction of the chromosome number from the normal diploid number to the
haploid number (half of the diploid number).
metestrus
The stage of the estrous cycle after ovulation, when the
corpus luteum develops. It occurs between estrus and diestrus
milk letdown
The let-down reflex is what makes breastmilk flow
mitosis
Cell division of somatic cells for growth and to replace
old or dead cells; the type of cell division that occurs in all body
cells except the reproductive cells. When cells divide by mitosis,
the chromosomes first duplicate themselves and then pull apart
into two daughter cells. This preserves the diploid chromosome
number
monoestrous
An animal that has only one estrous cycle each year.
morula
The solid mass of cells into which the zygote has developed a few days after fertilization of the ovum. It resembles a
tiny raspberry.
multiparous
An animal that normally gives birth to more than
one offspring at parturition.
myoepithelial cell
Cells in the mammary glands that have characteristics of both muscle cells and epithelial cells. They surround the alveoli and small ducts of the glands.When stimulated
by the hormone oxytocin, they contract, squeezing milk down
into the large ducts and sinuses; see milk let-down.
neonatal period
The first few weeks and months after birth.
oocyte
The immature form of the female reproductive cell.
oogenesis
The production of female reproductive cells (ova) in
ovarian follicles
orchiectomy
A surgical procedure by which the testes are
removed from a male animal; castration.
os penis
The visceral bone in the penis of dogs that partially
surrounds the penile portion of the urethra.
ovarian follicle
The fluid-filled structure in the ovary in which
immature oocytes develop into mature ova. The lining cells of
the follicle, the granulosa cells, produce estrogen hormones.
ovary
The female gonads; they produce the female reproductive cell, the ovum, as well as estrogen and progestin hormones;
homologous to the testes of the male.
oviduct
Also called the Fallopian tubes or uterine tubes; the
oviduct, by way of ciliary movement, transports ova from the
ovary via the infundibulum to the uterus; the site of fertilization
in many species; tubular extension of the uterine horn.
ovulation
The traumatic rupture of a mature ovarian follicle that
releases the ovum.
ovum
plural, ova) The mature female reproductive cell. The
ovum is released from the mature follicle into the oviduct for
fertilization by spermatozoa. The female gamete.
pampiniform plexus
The network of veins in the spermatic cord
of the male. It is derived from the testicular vein and surrounds
the testicular artery. It functions as a heat-exchange mechanism
that helps keep the testes slightly cooler than the rest of the body
without cooling the body as a whole.Warm blood coming down
the testicular artery is cooled by the blood in the pampiniform
plexus; at the same time, the blood in the plexus, which is
returning to the systemic blood supply, is warmed by the blood
in the artery
parturition
The birth process.
parietal vaginal tunic
The thick outer connective tissue layer
around the testis and spermatic cord. Derived from parietal
peritoneum. Also called the common vaginal tunic
passive immunity
The transmission of intact, preformed antibodies from one animal to another. The antibody molecules can
help protect the recipient animal from disease-causing agents.
An important source of passive immunity is colostrum, the first
secretion of the mammary gland after parturition. If it is drunk
by the newborn within the first few hours after birth, the antibody molecules will be absorbed into the bloodstream intact
and help protect the newborn; however, after that time, the
antibody molecules will be broken down by digestion and not
absorbed intact.
penis
The male copulatory organ; homologous to the clitoris of
the female.
placenta
A life-support system for a developing fetus; a multilayered, fluid-filled, membranous sac that surrounds the fetus and
links it to the blood supply of the uterus. There is normally no
direct mixing of fetal and maternal blood, but the blood vessels
are close enough to each other that nutrients, wastes, and respiratory gases are easily exchanged between the fetal and maternal
bloodstreams. It is also an important endocrine organ. At parturition, it is delivered last; so it is sometimes referred to as the
afterbirth.
Placentome
The attachment site with the uterine lining for cotyledonary placentas. It is formed from the tight connection of a
cotyledon on the surface of the placenta with a caruncle in the
lining of the uterus. Normally, large numbers of placentomes
link the placenta with the uterus.
polar body
A “garbage can” for excess chromosomes. The polar
body is a by-product of ovum development in the ovarian follicle; it will not develop into a mature ovum.
polyestrous
An animal that has continual estrous cycles if she is
not pregnant. As soon as one cycle ends, another begins
Prepuce
The skin-covered sheath around the free end of the
penis.
proestrus
The stage of the estrous cycle when follicles are actively
developing and growing in the ovary. As they grow, the follicles
produce rising levels of estrogens, which gradually induce the
physical and behavioral changes that prepare the animal for
breeding.
progestin
Hormones produced by the corpus luteum of the
ovary. They are necessary for the maintenance of pregnancy,
particularly during the early gestational period. The principal
progestin hormone is progesterone.
proper vaginal tunic
The inner connective tissue sac that surrounds the testis. It is derived from the visceral peritoneum that
covered the testis during its early development in the abdominal
cavity. Also known as the visceral vaginal tunic.
prostate gland
The male accessory reproductive gland that generally surrounds the urethra; it lies just distal to the urinary
bladder. The prostate gland is the only accessory reproductive
gland in the dog, so it is quite large in that species
pseudocyesis
Pseudopregnancy; an abnormally prolonged and
exaggerated diestrus period that results in an animal acting
and looking pregnant when it is not. Most cases resolve
spontaneously
pseudopregnancy
an abnormally prolonged and
exaggerated diestrus period that results in an animal acting
and looking pregnant when it is not. Most cases resolve
spontaneously.
quarter
(1) The common name for the mammary glands that
make up the udder of the cow.(2) The medial and lateral regions
of the hoof.
urachus
A tube in the umbilical cord that drains urine from the
fetus’s urinary bladder into the allantoic sac of the placenta.
urethra
The tube that connects the urinary bladder with the
outside world. In the female, it only conducts urine. In the male,
it conducts urine and semen
urethral process
The distal end of the urethra of the male horse
that extends from a shallow depression, the fossa glandis, at the
tip of the penis.
uterine contraction
Contractions of the myometrium, the
smooth muscle layer of the uterine wall.
uterus
The womb; where the fertilized ovum implants and lives
while it grows and develops into a new animal.
vagina
The tube that connects the cervix with the vulva. It
receives the erect penis at breeding and serves as the birth canal
at parturition.
vaginal tunic
Two connective tissue layers that surround the
testes in the scrotum. They are derived from layers of peritoneum that were pushed ahead of the testes when they descended
through the inguinal rings into the scrotum.
vas deferens
The muscular tube that carries spermatozoa and
the fluid they are suspended in from the epididymis to the
urethra for emission as a component of semen
vestibule of the vulva
The entrance into the vulva; the short
space between the labia and the entrance into the vagina. The
urethra of the female opens into the vestibule.
visceral vaginal tunic
The thin, inner connective tissue layer that
is tightly adherent to the surface of the testis and the structures
of the spermatic cord. Derived from visceral peritoneum.
vulva
The external portion of the female reproductive system. It
consists of the vestibule, the clitoris, and the labia
zona pellucida
Thick, gel-like glycoprotein layer that surrounds
the cell membrane of a developing oocyte in an ovarian follicle,
and an ovum after ovulation.
zonary placental
attachment
The type of placental attachment
to the uterus that is in a belt-shaped area that encircles the
placenta; found in dogs and cats.
zygote
The fertilized ovum.
