Histology Male and Female Reproductive Systems

Functions of Female Reproductive System (FRS)

- Produce and transport ova
- Provide environment for fertilization
- Sexual intercourse
- Provide nutrition
- Support growing embryo
- Give birth

Organs of FRS

2 ovaries
2 oviducts
Uterus
Cervix
Vagina
Mammilary Gland
Placenta

*Note ovary is not physically connected to oviduct

Ovary

- Covered in Cuboidal Epithelium
- Tunica Albuginea lies beneath epithelium
- Cortex: Contains follicles (sites of egg production)
- Medulla: Highly vascular

* Called germinal epithelium, but is not a germ cell line
* 70% of ovarian cancers grow in ovary

Oocyte Development

- Occurs in ovary
- At birth, 2million oocytes
- By puberty 400,000
- Per month, 30-40 mature
- 480 total oocytes/year
- Only 12 mature oocytes per year/40 years
- Other stimulated follicles either mature in another cycle or degenerate (only 1 is ovulated per cycle)

Follicular Development

- Primordial (25 micrometers)
- Primary Follicle (125 micrometers) --> go from unilaminar to multi laminar
- Secondary Follicle (200 micrometers)
- Graffian Follicle (2.5cm)

Primordial Follicles

Unilaminar and quiescent. Single layer of FLATTENED follicular cells

Unilaminar Primary Follicles

Single layer of cuboidal follicle cells around oocyte

Multilaminar Follicles

Many layers of cuboidal (granulosa) cells around oocycte. Zona pellucida forms (very important). Theca Intera and Externa develop.

Granulosa Cells

- Nourish oocyte
- Communicate with oocyte
- Express aromatase (converts androgens to estrogens)
- Secrete inhibin to inhibit FSH (****)

Zona Pellucida

- Forms between granulosa cells
- Composed of at least 3 glycoproteins
- Contributed from both oocyte and granulosa
- Processes of oocyte and granulosa cells penetrate zona pellucida and communicate via gap junctions

Theca Interna

Surround multilaminar primary follicles. Stromal cells that will secrete steroids

Theca Externa

Found superficially to theca interna

Secondary Follicles

Has fluid filled cavity--> known as an antrum. Granulosa cells and oocyte begin to be concentrated on ONE side.

- Antrum contains: glycoproteins, steroid binding proteins, progesterone, etc.

Graffian Follicles

"mature" follicles. Final stage of development.

- Contain granulosa cells on one side.
- Cumulus oophorus: mound of granulosa cells
- Corona radiata: layer of granulosa cells that specifically surround oocyte (still present at fertilization)

Atretic Follicles

- Apoptosis of follicles
- Degeneration can occur at many phases of development
- Hallmark: collapsed zona pellucida
Stages of normal Gametogenesis:
- Primary oocytes are arrested in prophase of first meiotic division
- LH surge at ovulation stimulates completion of first meiotic division
- Products are secondary oocyte and polar body
- Second meiotic division is completed at fertilization

Ovulation and Corpus Luteum

- Surge in LH results in ovulation and extrusion of mature follicle
- Temporary endocrine gland formed by the remnants of follicle
- Granulosa lutein cells produce progesterone (from granulosa cells)
- Theca lutein cells secrete estrogen (derived from theca interna)

Corpus Albicans

When pregnancy does not occur, corpus luteum only lasts 10-14 days, regresses and the albicans is formed

Corpus Luteum and Pregnancy

When pregnancy occurs, HCG is produced and maintains the corpus luteum

Female Contraception

Goal is to trick body into not ovulating. Exogenous estrogen and progestin are added.
*Progestin: Inhibits LH surge, thickens cervical mucus, decreases estrogen driven cell proliferation, reproductive tissue becomes functional rather than proliferative
Estrogen: Inhibits FSH surge and follicle development. May inhibit ovulation. Thins cervical mucus
Oral contraceptives suppress LH and FSH releases--->decrease estrogen and progesterone

Infertility Causes

In couples
- Males contribute at 1/3
- Ovulatory dysfunction at 15%
- Tubal patholgy 35%

*Numbers increase for woman alone
* IVF can be used to assist reproduction.

Differences between FRS and MRS

Timing: Constant (M) 12hr/mo (F)
Germ Cells: Mitotic replacement (M) fixed supply (F)
Endocrine Pattern: Acyclic (M) cyclic (F)
Control: Hypothalamus (M) Hypothalamus and Corpus Luteum (F)

*Androgen and estrogen affect distinct somatic tissues!

Oviduct Function

Conducts ova from ovary to uterus
Site of fertilization
Oviduct=fallopian tube=Uterine Tube

Aspects:
- Infundilbulum (near ovary, contains fibria)
- Ampulla (folded epithelium, peristaltic actions)
- Isthmus (near uterus)

Oviduct Characteristics

- Ciliated simple columnar epithelium, contains secretory cells
- Lamina propria underneath
- Smooth muscle
The epithelia in particular help propel fertilized ova to uterus. Changes during menstrual cycle (number of ciliated cells increases) and are absent in menopause

Secretory Cells

Peg Cells. Secrete substances that protect ova and stimulate capacitation of spermatozoa

When Sperm Meets Egg

1) Binding to zona pellucida
2) Acrosomal reaction
3) Penetration
4) Fusion of plasma membrane
5) Sperm nucleus enters egg cytoplasm

Uterus Function

- Specialized for nurturing and carrying fetus
- Divided into endometrium and myometrium

* Ectopic pregnancy can occur when egg gets caught in fallopian tube instead of making it to uterus

Endometrium

In the uterus.
Complex epithelium with two layers
- Stratum basale: Not lost during menstruation
- Stratum functionalis: superficial layer that grows and is sloughed off and reforms over the residual basal layer

Premenstrual Stage

1) Contractions of the spiral artery (triggered by reduction
2) Breakdown of spiral artery--> lamina propria fills with blood
3) Functional layer detaches and sheds
4) Basal layer not affected

Myometrium

- Muscular wall of uterus
- Interlacing bundles of smooth muscle
- During pregnancy smooth muscle cells divide and grow

Three Phases of Menstrual Cycle

- Proliferative
- Secretory
- Menstruation

* notable changes in appearance occur

Proliferative Phase

Days 5-14
- Controlled by estrogen
- Re-establishment of stratum functionalis
- Endometrial glandular epithelial cells are tall columnar, mitotic figures are frequently present
- Glands are straight, with narrow lumens

Secretory Phase

Days 15-28

- Controlled by corpus luteum and progesterone
- Glands continue to elongate, become wavy, lumen becomes dilated with secretory products
- Endometrial cells accumulate glycogen
- Changes assure for a receptive environment for potential implantation

Menstrual Phase

Days 1-4

- Characterized by loss of stratum functionalis
- 2 weeks after ovulation in the absence of fertilization, progesterone is lost
- Progesterone withdrawal leads to constriction of coiled arteries
- Impaired blood flow causes degenerative changes and epithelium break down
- Menses consists of blood, glandular epithelium

Cervix

Connects uterus to vagina. Lined by simple columnar epithelium. Cells produce mucous. Cervical mucous secretions vary through cycle

- Proliferative phase (watery, allow for sperm passage)
- Secretory phase (muscous is viscous)

Vagina

Fibromuscular tube lined by stratified squamous epithelium. Produces glycogen (a substrate or bacteria to allow for lower pH). Lubrication is provided by cervix.

Mammary Gland

Many important components of breast milk (secretions from alveolar cells). Include: Fat, IgA, Lactose, Proteins. Stimulated by Prolactin and oxytocin.
Alveolar duct epithelium grows and forms secretory alveoli during pregnancy. During lactation, alveoli become distended with milk

Male Reproductive Organs

Testes
Epididymis
Vas Deferens
Seminal Vesicles
Prostate
Urethra
Penis

Male Reprod. Functions

- Testis: production of spermatazoa and sex hormones
- Genetial ducts: collect, store and conduct spermatozoa from each testis
- Accessory glands: secrete nutritive and lubricating fluid called seminal fluid
- Penis: Copulating organ

Testes

Localization and Structure:
- Situated external to the body cavity in scrotum. Maintained below body temp (35 degrees). Necessary for spermatogenesis
- Surrounded by tunica vaginalis (protects testes)
- Beneath this layer, dense fibrous CT
Function:
- Seminiferous tubules (site of sperm production)
- Leydig cells (site of testosterone production)

(1)Spermatogenesis and (2)Spermiogenesis

1. Spermatogenesis: Meiosis I and II. Begins at puberty, each spermatocyte produces 4 sperm. Continues throughout life (very different than oogenesis!)
- Process
Spermatogonia type A-->
Spermatogonia type B-->
Primary spermatocytes-->
(first meiotic division) Secondary spermatocytes

2. Maturation from spermatid to spermatozoa. Morphological change and acrosomal head development.
- Process
Spermatids--->Spermatozoa

Sperm Structure, Localization, and Division

- Lined by germinative epithelium, which contains cells of spermatogenic series and Sertoli cells
- Spermatogonia reside in basal layer and divide at puberty--> give rise to spermatocytes which become spermatids which beomce spermatozoa

Spermiogenesis Phases

Golgi Phase: Proacrosomal granules accumulate in golgi, centrioles move to end opposite from acrosome

Acrosomal Phase: Acrosome contains hydrolytic enzymes needed to digest zona pellucida. Flagellum formation, mitochondria agregate. Condensed nucleus.

Maturation Phase: Shedding of residual cytoplasm

Sertoli Cells

- Nutritional support for spermatozoa
- PHAGOCYTIZE residual bodies shed during spermiogenesis
- **Produce androgen binding protein and inhibin
- Produce anti-mullerian hormone

* Binds FSH

Blood-Testes Barrier

Tight junctions speparate luminal and basal sides. Spermatozoa are NOT viewed as foreign (protected from immune system and blood borne toxins).

Sertoli Cell Morphology and Localization

Extend from basement membrane to lumen. Ovoid pale staining nucleus. Irregular cellular outline

Leydig Cells

- Reside in interstitial spaces between tubules.
- Under the influence of LH (* bind LH), they produce testosterone.
- Steroid secreting cells (abundant sER and golgi)

Endocrine Function in Male Reprod.

Sertoli Cells
- Receptors for FSH
- Produce androgen binding protein (binds testosterone)
- Produce inhibin (involved in feedback inhibition of FSH)

Leydig Cells
- Receptors for LH
- Produce testosterone (negative feedback loop

Tubuli Recti

Straight part of seminiferous tubules. Join rete testes

Rete Testis

Intratesticular. Lined by low cuboidal epithelium

Efferent Ductules

Extratesticular. Connect rete testis with epididymis. Contains simple cuboidal and ciliated columnar epithelium

Epididymis Functions

- Modification of ejaculate contents
- Maturation (motility)
- Storage

Epididymis Structure

Lined by *pseudostratified columnar epithelium. Tall cells have stereocilia. Short cells are stem cells.

Vas Deferens Structure

- Epithelium: Pseudostratified columnar with stereocilia
- Thick muscular coat (inner longitudinal, middle circular, outer longitudinal)
- Adventitial layer (nerves and blood vessels)

Vas Deferens Function

Peristaltic contractions of thick muscular coat propel spermatozoa from epididymis to urethra. Sympathetic stimulation during ejaculation

Vasectomy

Each vas deferens is cut. Prevents passage of sperm

Seminal Vesicle as Exocrine Gland

- Paired glands
- Epithelium: Pseudostratified
- Protein secretory cells
- Dependent on testosterone
- Muscle: Inner circular, outer longitudinal
- Contraction of muscle during ejaculation

Seminal Vesicle Function

Produces yellow alkaline fluid (70% of ejaculate). Fructose, citrate, prostaglandins, proteins

Prostate Gland

- Surrounds urethra
- Folded mucosa
- Epithelium varies from tall cuboidal to pseudostratified columnar
- Produces prostatic fluid (citric acid, acid phosphatase, amylase, etc.)
- Fibroelastic tissue containing smooth muscle surrounds glands and contracts during ejaculation filling urethra.
- Concretions: Corpora Amylacea (fill glands lumen, increase in number and size with age. Become calcified)

Bulbourethal Glands

- Paired glands (Cowper gland)
- Located at the *Beginning of the membranous urethra
- Stimulation causes release of mucus secretion (major portion of preseminal fluid)

Semen

Consists of 3ml of fluid. Up to 100million sperm/ml. Alkaline helps neutralize acidic environment of female reprod. system.

Penis

- Sex organ, urine excretion

Anatomy
- Paired corpora cavernosa and a single midline corpus spongiosum.
- Bound together by fibrous CT capsule

Corpus cavernosa fills with blood during erection
- Helicine arteries dilate upon stimulation and fill with blood
- Arteriovenous (AV) anastomosis between the artery of the penis and peripheral venous system closes also increasing blood flow.
- Peripheral veins compressed

Innervation
- Parasympathetic, sympathetic, and spinal

Viagra

Potent inhibitor of PDE5 by inhibiting cGMP-specific PDE5. cGMP promotes smooth muscle relaxation-->allows for increased blood flow. Inhibition of PDE5 maintains concentrations of cGMP necessary for erection maintenance.

Pathway for Sperm Release

Seminiferous Tubules--->straight tubule--->Rete Testes---> Efferent Ductule--->Epididymis---> Vas deferens

Menstrual Cycle Hormonal Characteristics

- Pituitary Hormones: Both FSH and LH stimulate follicle development, but LH surge prior to secretory phase triggers ovulation

- Ovarian Cycle: Divided into follicular phase and luteal phase

- Ovarian Hormones: Estrogen is high for first half and levels off. Progesterone starts very low, but rise high in second half.