Reproductive system - Systematic Pathology II

What are some requirements for reproductive function?

• Functional gonad

• Intact hypothalamic-pituitary-gonadal axis

• Structural integrity of reproductive tract

• General good health and nutritional status

What examining the reproductive system, what should always be considered?

The current hormonal environment and the normal changes that occur with age, cyclicity, and season.

Sexual differentiation in the mammalian embryo has three sequential steps

1. Sex chromosome type established at fertilization (XX or XY)

2. Gonadal type established early in development (ovaries or testes)

3. Establishment of sex phenotype: arrangement of tubular and external genitalia - including regression of some parts (uterus, vagina, vulva, clitoris or ductus deferent, penis, prepuce, scrotum.

Note: there are many mechanisms of sex determination in living things, but we are only focusing on one form (genotypic, mammalian)

The mesonephric (Wolffian) duct is associated with males or females?

Males

The paremesonephric (Mullerian) duct is associated with males or females?

Females

In XX embryos, differentiation of the female phenotype occurs in the absence of functional testes and several genes are involved. Which structures form the female gonads?

• Paramesonephric (Müllerian) ducts → uterine tubes, uterus, cervix, cranial vagina

• Urogenital sinus → caudal portion of the vagina

• Mesonephric (Wolffian) ducts regresses (+/- vestigial remnants)

In XY embryos, differentiation is due to the presence of what?

Translated protein product of Sry gene (Sex-determining region of Y)

Which structures are involved in the formation of male gonads?

• Y chromosome → SRY protein product → primitive gonads → testes

• Testicular interstitial (Leydig) cell precursors → testosterone and dihydrotestosterone → Mesonephric ducts (Wolffian) → male reproductive system (efferent ducts, epididymis, ductus (vas) deferens).

• Testicular sustentacular (Sertoli) cells → Anti-Müllerian hormone

(AMH) → Paramesonephric (Müllerian) duct regresses (+/- vestigal remnants)

Define Disorders of Sexual Development (DSDs)

Congenital conditions in which development of chromosomal, gonadal, and/or anatomic sex is atypical.

Complete categorization of DSDs require assessment of:

1. Sex chromosomes (karyotype) and/or genetic analysis (XX, XY, or other; SRY+ or SRY-)

2. Gonadal type (ovarian, testicular, ovotesticular)

3. Genital phenotype (internal and external genitalia +/- secondary sex characteristics)

Categories of DSD if karyotype is known

1. Abnormal or missing sex chromosome(s)

2. XX Karyotype: disorders of ovarian development, androgen excess, miscellaneous.

3. XY Karyotype: disorders of testicular development, androgen synthesis or action, etc.

Note: disorders with an XX or XY karyotype are subdivided into SRY+ and SRY- genotypes.

Sex chromosome DSDs

True sex chromosome DSDs are rare, but chimerism (XX/XY) is more common: freemartinism

Examples of true sex chromosome DSDs

XXY: Klinefelter-like syndrome

X_: Turner-like syndrome

XXX: Trisomy X

Associated with gonadal dysgenesis (hypoplasia) → small under developed gonads.

What is chimerism: freemartinism?

• Two somatic cell types from different individuals (XX and XY)

• XX embryo twin with XY embryo

• 90% of XX with XY twins in cattle (XX is often the freemartin)

• 1% in sheep

• Reported in goats, cervids, swine, camelids

What is the pathogenesis of freemartinism?

XX embryo co-twin with XY embryo → Placental vascular anastomoses → Exchange of blood between fetuses → Female exposed to SRY protein early in development → Ovarian hypoplasia, ovotesticular differentiation → Hormonal imbalances: production of AMH and testosterone, reduced estrogens → Abnormal genital development and infertility (lesions of freemartinism)

Note that both XX and XY karyotypes are present in blood.

Freemartinism lesions (vary, but include the following)

A. Hypoplastic ovaries resembling testes, or ovotestes

B. Hypoplastic uterus

C. Enlarged clitoris

D. Vestigial paired seminal vesicles

E. Blind-ended vagina

What is Mosaicism

Two or more somatic cell populations with different genetic or chromosomal make-up within a single individual, originating from a single zygote.

E.g., calico and tortoiseshell cats.

Mosaicism: calico and tortoiseshell cats

• Genes controlling orange and black coat colour are on X-chromosome

• Random X inactivation of one X per cell in early embryo

• ALL are XX if genetically normal

• 1/3000 are male: these are usually XXY and infertile

If sex chromosomes are unknown, DSDs are simply classified by gonadal type:

1. Gonadal dysgenesis DSD

2. Testicular DSD (“male pseudohermaphrodite*”)

3. Ovarian DSD (“female pseudohermaphrodite*”)

4. Ovotesticular DSD (“true hermaphrodite*”).

• All four of these DSDs are also referred to as Intersex Conditions.

• Pseudohermaphroditism (older term but still used) is also called “sex reversal”.

Note: term hermaphrodite is outdated now.

Gonadal dysgenesis DSD

• Failure of gonadal hormone production → failure of development of secondary sex characteristics → sexually infantile (prepubertal) female appearance & infertility

• Often chromosomal: XXX, XXY, X_

Testicular DSD

• Testes

• Female, feminized, or ambiguous external genitalia

• E.g., Lack of AMH receptors (miniature schnauzer)

• More common than ovarian DSD

Ovarian DSD

• Ovaries

• Male, masculinized, or ambiguous external genitalia

• Causes include: iatrogenic admin of steroids to dam, fetal adrenal hyperplasia

Ovotesticular DSD

• Both types of gonadal tissue present (testis/ovary or ovotestis)

• External genitalia are often ambiguous (depends on the amount of testosterone produced by the testicular tissue during gestation)

Types of developmental anomalies in the ovary

Ovary genesis and ovarian dysgenesis (hypoplasia)

Ovarian genesis

• Failure of development (absent)

• Uni- or bilateral. Rare.

• Birds normally lack a right ovary

Ovarian dysgenesis (hypoplasia)

• Described in several domestic species.

• Often associated with chromosomal DSDs (X_, XXX, XXY)

• Small ovaries that lack follicular activity.

• Ovarian hypoplasia is autosomal recessive in Swedish Highland cattle

Developmental anomalies: paramesonephric duct (Uterine tubes, uterus, cervix, cranial vagina)

Segmental aplasia and imperfect fusion of paramesonephric ducts

Segmental aplasia can…

Occur at any level of tubular reproductive tract

Developmental anomalies: persistent hymen

• Failure of fusion of the paramesonephric ducts with urogenital sinus.

• Band of tissue across floor of vagina cranial to urethral opening

• Incomplete: not significant

• Complete (imperforate) hymen → accumulation of secretions upstream → distension and atony (may be permanent)

Developmental anomalies: cystic duct remnants

Cystic paramesonephric duct remnants

• Fimbrial cysts, “hydatids of Morgagni”

• Not clinically significant

Developmental anomalies: cystic duct remnants

Cystic mesoneprhic duct and ductule remnants

• Thin walled, moveable, around the ovary (paraovarian cysts) and around uterine tube.

• Not clinically significant.

Diseases of the ovaries: cystic ovarian disease

1. Follicular cysts (Cystic Graafian follicles) is caused by failure of mature follicles to ovulate.

2. Luteal (luteinized cysts)

Follicular cysts (Cystic Graafian follicles) is caused by failure of mature follicles to ovulate.

• Absence or mis-timing of lutenizing hormone (LH) surge from pituitary or lack of receptors. Associated with cortisol excess, uterine infection, genetic predisposition, and more.

• Can be larger than normal (for the species). ( E.g., cattle: cystic follicle defined as >/= 2.5 cm)

• Can persist longer than normal. (E.g., cattle: persistence is defined as >/= 10 days)

• Can be single or multiple.

• Can produce estrogen and cause signs of hyperestrogenism → prolonged estrous cycles or anestrus, nymphomania, valvular edema, enlarged clitoris.

Normal maximum mature follicle sizes:

Cow: 20 mm

Sheep: 10 mm

Goat: 10 mm

Pig: 10 mm

Dog: 7.5 mm

Horse: 70 mm

Polycystic ovarian disease in dogs

In dogs, polycystic ovarian disease is uncommon but associated hyperestrogenism can cause bone marrow suppression and pancytopenia, sometimes fatal

1. Luteal (luteinized cysts)

• Caused by failure of mature follicles to ovulate (as in follicular cysts) but then granulosa and theca cells luteinize (as if forming a corpus luteum)

• Milder disease, less common

• Secrete progesterone and may cause anestrus

• Sows are prone to multiple luteinized cysts: may have endometrial hyperplasia (progestational hyperplasia) and enlarged clitoris.

Diseases of the ovaries: Primary ovarian neoplasms

1. Gonadal stromal tumors (sex-cord stromal tumors)

2. Adenomas and adenocarcinomas

3. Germ cell tumors (Dysgerminomas, Teratomas)

4. Hemangiomas (sows)

Gonadal stromal tumors (also called sex cord stromal tumors)

• Arise from granulosa cells and theca cells, and can luteinize

• Solid or multicystic

• Frequently productive (estrogens, progesterone, androgens, inhibin)

• Often have ATROPHY of contralateral ovary

Associated with:

• Hyperestrogenism in 50% of cases in dogs

• Nymphomania and masculine behavior in cows

• Anestrus, continuous estrus, or stallion-like behaviour in mares

Adenomas and adenocarcinomas

Papillary and cystic

Adenomas and Adenocarcinomas

• Arise from surface epithelium

• Common only in dogs

• Often bilateral

NOTE: Cystic endometrial hyperplasia in dogs can occur in association with any of several ovarian neoplasms (gonadal stromal tumors, carcinomas, etc).

3. Germ cell tumours - Dysgerminoma

• Ovarian equivalent of seminoma

• Pale tan, solid, soft, bulging, +/- hemorrhage, necrosis

• Metastases rare

Germ cell tumours - Teratoma

• Most are benign in domestic animals (contrast to humans)

• Puripotential germ cells

• Differentiated into different tissue types (ectoderm, mesoderm, endoderm – at least 2 layers)

• Skin, muscle, fat, gut epithelium,

Hemangiomas

• Most common ovarian tumor in sows 5-8 years old

• Believed to arise from blood vessel growth in the corpus luteum

Oviduct = Uterine tube = Fallopian tube

(Mammalian characteristics)

• Fimbriae collect ovulated oocyte

• Delicate ciliated epithelium propels oocyte toward the uterus.

• Site of fertilization

• Less capacity for repair than endometrium

Diseases of the oviducts

1. Hydrosalpinx

2. Salpingitis

Hydrosalpinx

Secondary to obstruction

• Segmental aplasia

• Inflammation

• Adhesions secondary to manual ovarian manipulation in cows

Distension with secretions

Salpingitis

• Usually secondary to endometritis

• May lead to pyosalpinx.

• Even minor inflammatory changes important

Non-inflammatory diseases of the uterus

• Uterine rupture

• Uterine torsion

• Uterine prolapse

• Endometrial polyps

• Endometrial hyperplasia

• Hydrometra and mucometra

• Pseudopregnancy

• Subinvolution of placental sites

Uterine rupture causes and sequela (non-inflammatory disease of the uterus)

Causes: Trauma (parturition), torsion, iatrogenic (infusions, manipulations)

Sequelae: hemorrhage, perimetritis, peritonitis

Uterine torsion causes, who gets it + sequela (non-inflammatory disease of the uterus)

• Enlarged uterus: pregnancy, pyometra, mucometra, large uterine polyps

• Uncommon except cows and mares

• Cows: 90° torsions may resolve but 180°cause dystocia and circulatory disturbances

• Occurs at cervix in cows, single horns in carnivores

Sequelae: uterine rupture; if pregnant, dystocia, fetal death and mummification (closed cervix) or maceration/putrefaction (open cervix)

Uterine prolapse - who gets it, predispositions + sequela (non-inflammatory disease of the uterus)

• Usually post-partum

• Ruminants and sows

Predisposing factors: Uterine atony/hypotony, dysrhythmia

• Dystocia (+/- traction)

• Retained placenta

• Hypocalcemia

• Hyperestrogenism (legumes)

Sequelae:

• Hemorrhage, shock

• Uterine trauma, infarction, infection, infertility

Endometrial polyps - who gets it, ddx,, sequela (non-inflammatory disease of the uterus)

• Older female dogs and cats

• DDx neoplasia or hyperplasia

Characteristics:

• High proportion connective tissue stroma

• Pedunculated

• Sequelae: prolapse of uterine horn

• Uterine contractions → mechanically force polyp down horn → tension on the wall of the uterine horn → prolapse of the uterine horn

Endometrial hyperplasia - cause, sequela (non-inflammatory disease of the uterus)

Abnormal proliferation of endometrium

• Simple → cystic or adenomatous

Cause: excess hormonal stimulation

• Excess hormone production

• Excess response to endogenous or

exogenous hormones

Sequelae:

• Fibrosis (can affect fertility)

• Adenomyosis (see later)

Endometrial hyperplasia is associated with hat in dogs and cats?

Pyometra

Endometrial hyperplasia in ruminants and swine

Occurs in response to prolonged estrogen stimulation:

• Cystic ovarian disease

• Granulosa cell tumors

• Estrogenic forage (clovers)

• Zearalenone (mouldy feed): Sows

Endometrial hyperplasia pathogenesis in dogs and cats

Prolonged exposure to progestins after estrogen priming (E increases P receptors):

• Recurrent diestrual corpora lutea (intact dogs not bred) –> Progresterone → increase in SECRETORY mode of endometrium

• Low grade infection during luteal phase

• Luteal endometrium very responsive

• Stimulates endometrial proliferation

• Administration of progestin-type drugs (e.g., megestrol acetate, Ovaban®)

• Also occurs with ovarian follicular cysts and ovarian tumors (any)

• Estrogen or progesterone

Hydrometra and mucometra (non-inflammatory disease of the uterus)

• Watery or mucoid fluid / secretion accumulation in uterus

Causes:

• Obstruction

• Segmental aplasia

• Imperforate hymen

• Torsion

• Endometrial hyperplasia

• Glands produce excess fluids

Pseudopregnancy (dogs) cause, pathogenesis, sequela (non-inflammatory disease of the uterus)

Exaggerated form of normally long luteal phase in dogs.

Luteal phase (presence of CLs) → prolonged progesterone secretion then decline, often with increased PROLACTIN → Exaggerated response → Various changes typically associated with pregnancy / early post-partum → Mammary development, sometimes with lactation → Formation of placental sites → Mucometra → Behavioural changes (aggression, nesting, etc)

Possible sequela: pyometra

Subinvolution of placental sites who gets it, cause and sequela (non-inflammatory disease of the uterus)

• Young, postpartum female dogs

• Prolonged bloody vaginal discharge (weeks to months)

• Enlarged uterine horns, bands of dark red and proliferation

Cause: unknown

Sequelae: anemia; rarely, hemoperitoneum

Uterine defence mechanisms (innate vs adaptive)

(Inflammatory diseases of the uterus)

Defense mechanisms - innate

• Uterine motility (favored by estrogen)

• Migration of neutrophils (favored by estrogen)

• Mechanical barrier of cervix

Defense mechanisms – adaptive

• Humoral and cellular immunity – must be carefully controlled in order to tolerate spermatozoa and fetus

Reduced resistance to infection

(Uterine defence mechanisms - inflammatory diseases of the uterus)

1. Progesterone-induced immunosuppression

• Luteal phase of estrus

• Pregnancy

Results in inhibition of lymphocyte proliferation

2. Shortly after birth (uterine atony)

• Dystocia

• Trauma

• Retained placenta

• Delayed involution

Note: Most uterine infections are ASCENDING through the cervix but can be hematogenous, from ovary/uterine tube, or transneural (axonal).

Inflammatory diseases of the uterus

• Endometritis (inflammation of the endometrium)

• Metritis (inflammation of ALL layers of the uterine wall)

• Pyometra (accumulation of purulent exudate in uterine lumen)

Endometritis

• Inflammation of the endometrium

• Acute: Neutrophils in endometrial stroma

• Chronic: Lymphocytes, plasma cells in stroma

Endometritis interpretation of lesions requires knowledge of the stage of estrus/postpartum interval

• Cows, estrus and immediately postpartum: small # of leukocytes are expected.

• Male: neutrophils are ALWAYS abnormal (endometrial biopsies are an important breeding management tool in mares.

Specific examples of endometritis

Horses:

• Taylorella equigenitalis - “Contagious equine metritis”

• Temporary infertility, mucopurulent vaginal discharge, endometritis, cervicitis, salpingitis, vaginitis

• Carried by stallions and in clitoral fossa and sinuses in mares

• Reportable disease in Canada

• Imported horses tested & quarantined

Cattle:

• Venereal transmission, various agents (e.g., Tritrichomonas fetus)

• Early postpartum (dystocia, retained placenta)

**If CHRONIC: can cause retained CL and predispose to further infection**

Chronic endometritis pathogenesis

Chronic endometritis → failure of endometrium to release prostaglandin F2α → failure of luteolysis → retained CL → prolonged high progesterone levels → decreased immunity & maintenance of closed cervix & uterine atony (mimicking pregnancy) → pyometra and/or metritis

Metritis

Metritis: Inflammation of all layers of uterine wall

• Uterus paretic, little to no discharge

**In CATTLE, two forms of postpartum metritis**:

1. Toxic puerperal (postpartum) metritis: invasion by highly pathogenic bacteria. Can be systemic, severe.

2. Retained fetal membranes

• +/- systemic illness

• Spontaneous recovery may occur

• May become chronic or progress to pyometra

Pyometra

Accumulation of purulent exudate in uterine lumen.

Pyometra in dogs and cats

• Older, unbred

• Occurs a few weeks after estrus, during luteal phase (high progesterone environment)

• Closed cervix

• Progestational/proliferative endometrium

• E. coli most common pathogen

• DOGS: Often associated with cystic endometrial hyperplasia (CEH-pyometra complex)

Pyometra can be life-threatening in dogs and cats. What are the sequela?

Uterine rupture, peritonitis, sepsis/endotoxemia, bone marrow suppression, glomerulonephritis resulting from immune-complex deposition, uterine torsion.

Pyometra in cows

• Occurs postpartum, often assoc. with retained fetal membranes

• Various bacterial causes (e.g.,Trueperella pyogenes)

• Not typically systemic but can affect cycling (PGF2α ) → retained CL → hi progesterone/reduced fertility

Pyometra in mares

• Can occur when cervix is open

• Copious discharge!

• Not always postpartum

• Seldom leads to systemic disease

• Hormonal influences less important, continue cycling

• Various bacterial causes (Streptococcus zooepidemicus, E. coli, etc.)

• Drainage is important for treatment

Diseases of the vagina and vulva

• Tumefaction (hypertrophy and edema) of the vulva: normal in estrus, mycotoxin zearalenone (gilts)

• Vaginal polyps

• Vaginitis and/or vulvitis: many causes…(below)

• Bovine herpesvirus – 1: infectious pustular vulvovaginitis

• Equid herpesvirus – 3: coital exanthema (ulcerative vulvitis)

• Ureaplasma diversum: granular vulvitis in cows

Neoplasms of uterus, cervix, vagina, vulva

• Endometrial and cervical carcinoma

• Smooth muscle tumours

• Fibropapilloma

• Squamous cell carcinoma

• Uterine lymphoma (lymphosarcoma)

• Transmissible venereal tumour

Endometrial and cervical carcinoma (Neoplasms of uterus, cervix, vagina, vulva)

• Rare in domestic animals (despite frequency of endometrial hyperplasia)

• More common in cows and rabbits

• Most common spontaneous tumor in domestic rabbits

Smooth muscle tumours (Neoplasms of uterus, cervix, vagina, vulva)

• Most common canine tumor of uterus/vulva.

• Hormonal influence (follicular cysts, estrogen secreting tumors, endometrial hyperplasia)

Fibropapilloma (Neoplasms of uterus, cervix, vagina, vulva)

• Most common tumor of bovine vulva

• Caused by Bovine Papillomaviruses.

• Often young animals.

Squamous cell carcinoma (Neoplasms of uterus, cervix, vagina, vulva)

• In cows associated with UV light (poorly pigmented skin)

• Also identified in other species.

Uterine lymphoma (lymphosarcoma) (Neoplasms of uterus, cervix, vagina, vulva)

• Part of multicentric lymphoma associated with Bovine Leukemia

• Virus infection.

Transmissible venereal tumor (Neoplasms of uterus, cervix, vagina, vulva)

• A contagious tumor.

Ruminant placentae

• Interdigitating uterine and placental tissues (be able to define the

placentome and know the differences between caruncle and cotyledon)

• Maternal side: Caruncle (caruncular endometrium)

• Fetal side: Cotyledon (cotyledonary corioallantois)

Potential outcomes of diseases of placenta and fetus:

1. Early Embryonic Death

• Toxic or infectious agents or lethal chromosomal abnormalities

Can result in:

• Resorption (before bones are mineralized) -or -

• Expulsion +/- vaginal exudate if inflammatory

2. Fetal Death

• Abortion (before fetus is viable)

• Stillbirth (fetus is potentially viable, i.e., near or at term)

• Mummification

• Maceration

3. Perinatal Mortality

Fetal death: Mummification

• Dehydrated, dead, retained fetus

• Implies absence of bacterial infection and a closed cervix

• Retained indefinitely (uniparous)

• Expelled at parturition of live young (multiparous)

Common causes of fetal mummification (by species)

• Horses: Twinning

• Cattle: BVD; Tritrichomonas fetus infection

• Sow: Porcine parvovirus infection, “SMEDI” viruses (enteroviruses)

• Dog: Canine herpesvirus infection

• Cat: Torsion of a uterine horn

Fetal death: Maceration

• Requires presence of bacteria in the uterus

• Results in endometritis or pyometra

• Fetal emphysema if clostridial bacteria are involved → maternal toxemia and death

• Bones resist maceration → possible perforation

Pathology of the placenta and fetus.

Investigating pregnancy failure and abortion

Caused by nearly any disease that disrupts normal physiology

• Infections, toxins, inadequate nutrition, hormonal or chromosomal abnormalities, or physical influences.

Dx rate varies from 20% to 70%

Submit for diagnostic testing (pregnancy failure and/or abortion)

1. FETUS (no matter how autolyzed, mummified, or macerated)

2. PLACENTA

3. PAIRED SERUM SAMPLES FROM DAM

Infectious causes of pregnancy failure and abortion

DIAGNOSTIC CLUES

1. Timing (first, second, or third trimester)

2. Distribution of lesions in placenta (if any). Are the placentomes affected or the intercotyledonary regions affected?

3. Distribution of lesions in the fetus (if any)

Meconium (fetal feces) staining and aspiration suggest fetal STRESS in utero

**Only a few pathogens that specifically affect the placenta and/or fetus in domestic animals are discussed here.**

Examples of fetal lesions associated with infectious causes of abortion or neonatal death.

VIRAL

• Pestiviruses

• Parvoviruses

• Arteriviruses (PRRS)

• Herpesviruses

(ADD DIAGRAM???)

Bovine Herpesvirus-1 (Herpesviral infections leading to pregnancy failure)

• Infectious Bovine Rhinotracheitis (IBR) (BHV 1.1, respiratory subtype)

• Infectious Pustular Vulvovaginitis (IPV) (BHV 1.2, genital subtype)

IBR

• Abortion + widespread infection of fetal organs

• Severe upper respiratory disease (adults)

IPV

• Inflammation of the penis and sheath (balanoposthitis) in bulls / vagina and vulva

(vulvovaginitis) in cows

• Both can cause abortion

• ~ 4 months to term

• Autolysis is consistently present

• +/- small foci of necrosis in the liver

Canid Herpesvirus -1 (Herpesviral infections leading to pregnancy failure)

Adults

• Mild rhinitis

• Mild vaginitis / posthitis (inflammation of the prepuce)

• Abortion, stillbirth, mummification, or premature delivery

• Regularly fatal for newborn puppies (<2 weeks of age)

• Body temperature-related

• Multisystemic disseminated foci of necrosis and hemorrhage

Equid Herpesvirus-1 (EHV-1) (Herpesviral infections leading to pregnancy failure)

Respiratory & neurologic disease in adults

Aborting mares usually clinically normal

• Abortions 2-12 wks after infection

• Usually 3rd trimester (7 – 11 mos.; normal gestation is ~11 months; 320 –370 days)

• Fetus minimally autolyzed

• Late gestation exposure: live neonates with fulminating herpesviral pneumonia

Fetus: Multifocal necrotizing lesions (trachea, lungs, liver), inclusion bodies

Infectious causes of pregnancy failure and abortion:

BACTERIAL DISEASES

Brucellosis*

Campylobacteriosis

Leptospirosis*

Ureaplasma

Chlamydiosis*

Coxiella burnettii*

Listeriosis*^

Trueperella (Arcanobacterium)

pyogenes

*Zoonoses

^ Listeria is food-borne

***Add lecture 3 and 4 + pictures and written notes on slides