Reproductive - Anatomy E4

testes

Male primary sex organ, produces haploid gametes. Homolog to ovaries

scrotum

Externally demarcated by perineal raphe, homolog to labia majora

spongy urethra homolog

labia minora

glans penis/corpora cavernosa homolog

Glans clitoris

Corpus spongiosum homolog

Vestibular bulbs

Bulbourethral/Cowper’s gland homolog

Vestibular glands

Prostate gland homolog

Paraurethral/Skene’s glands

sperm pathway

produced in seminiferous tubules, matures in epididymis, vas deferens, ampulla of vas deferens, ejaculatory duct, prostatic urethra, membranous urethra, spongy/penile urethra, external urethral orifice

Dartos muscle

Smooth muscle in the superficial fascia of scrotum; wrinkles scrotal skin in cold

Cremaster muscle

Skeletal muscle that contracts to elevate testes in cold and relaxes in heat. 37°C is normal body temperature, spermatogenesis occurs at 34°C.

tunica vaginalis

Double serous membrane - visceral layer directly partially encloses testes and parietal layer lines scrotum. Derived from peritoneum, early scrotal cavity degenerates

tunica albuginea

White fibrous capsule; septa project inward to divide testes into lobules of seminiferous tubules.

spermatid pathway

seminiferous tubules, straight tubules, mediastinum testis containing rete testis, efferent ductules, epididymis

epididymis

Comma-shaped pseudostratified columnar epithelium hugging the posterior outer surface of the testes. Secretes enzymes and nutrients for functional sperm maturation. Stereocilia absorb extra secretions.

vas or ductus deferens

Pseudostratified columnar epithelium tube that stores and transports sperm to urethra. Thickens into an ampulla behind the bladder. Joining with seminal gland forms ejaculatory duct. Extremely thick muscularis for peristalsis surrounded by adventitia.

pampiniform plexus

Venous network of the spermatic cord that becomes testicular vein. Site of countercurrent heat exchange

countercurrent heat exchange

Veins of pampiniform plexus surround testicular arteries and absorb their heat to keep the testes cool (34°C)

spermatic cord

Fascia housing testicular artery, pampiniform plexus/testicular vein, ductus deferens, and nerves. Passes through inguinal canal to suspend testicles.

seminal vesicles 

Glands inferior to ampullae of vas deferens on posterior bladder surface, contribute 60% of semen volume. Yellowy viscous fluid contains fructose and prostaglandins, that make cervical mucosa receptive to sperm and reverse uterine tube peristalsis.

prostate gland

Tubuloalveolar gland embedded in fibromuscular stroma, contributes 30% of semen volume. Milky-white fluid contains substances that enhance sperm motility and liquify ejaculated semen and vaginal fluids (eg. prostate specific antigen).

bulbourethral or Cowper’s glands

Pea-sized glands inferior to the prostate within the urogenital diaphragm. Secrete alkaline lubrication which lubricates and neutralizes trace acids from urine residues in male urethra.

urogenital diaphragm

Contains membranous urethra and external urethral sphincter, not orifice

corpus spongiosum

Inferior penile erectile tissue that that keeps spongy/penile urethra open during erection. Bulb is secured to urogenital diaphragm and os coxa.

corpora cavernosa

Paired erectile tissue that fills with blood during erection. Paired crura anchor penis to the pubic arch of os coxa.

ovarian medulla

Vascularized region of ovary

ovarian cortex

Avascular region of ovary; has follicles containing oocytes

Broad ligament

Fascia that attaches uterus and ovaries to abdominal wall and encompasses the whole pelvic cavity. Contains round ligament that anchors uterus to pelvic wall anteriorly.

Suspensory ligament

Sheath containing ovarian artery and vein; attaches ovary to pelvic wall laterally.

Ovarian ligament

Deep to fallopian tube; connects ovary to uterus medially

Isthmus of uterine tube

Medial portion; attaches directly to uterus

Ampulla of uterine tube

Thickened middle portion between isthmus and infundibulum

Infundibulum of uterine tube

most distal curved portion of uterine tube

fimbriae of uterine tube

Ciliated feather projections that help guide the egg from the ovary

Fundus

Uppermost curved region of uterus.

Body

Middle majority region of the uterus, contains uterine cavity where a fetus would grow.

Isthmus of uterus

Inferior region where the uterus narrows but tissue is still smooth.

Cervix

Ridged boundary between uterus and vagina. Canal contains internal orifice, the upper opening into the uterus, and external orifice, the lower opening into vagina. 

Vagina

4 vaginal fornices lie immediately ventral, dorsal, lateral to the cervix. Hymen is a mucous membrane sometimes covering the vaginal orifice, either partially or fully. Effacement - cervical thinning.

perimetrium

Most external pinky covering of the uterus. A serous membrane made of simple squamous epithelium over areolar connective tissue.

Myometrium

Smooth muscle wall of the uterus that contracts during childbirth.

Endometrium

Simple columnar epithelium of secretory and ciliated cells. Functional layer (apical) sheds during menstruation; basal layer rebuilds the functional layer between periods.

Labia majora

Outermost and largest folds of skin surrounding vaginal orifice; keratinized stratified squamous epithelium.

Labia minora

Medial inner folds surrounding vaginal orifice; non-keratinized stratified squamous epithelium. 

Vestibule

Space between labia minora; houses vaginal orifice, external urethral orifice, and ducts of vestibular glands.

Clitoris

Unexposed paired corpora cavernosa with crura attached to pubic arch

Vestibular gland and bulb

Circular, posterior vaginal gland that secretes mucus to help with lubrication. Elongated anterior tissue bulb lies anteriorly, constricts vagina during intercourse.

lactiferous duct

Thick tubes within the breast

lactiferous sinus

Area where lactiferous ducts converge to form the nipple

2ndary sex characteristics

Hair in axilla, pubic, and facial region (in males). Apocrine scent glands. Muscular development in males, breast development in females. Body fat distribution and voice pitch.

testicular descent

Initiated at 6-10 wks gestation, complete by 28 weeks. Caused by shortening of gubernaculum, a fibromuscular cord from scrotal swelling to internal testis

male 2ndary sex organs

Form glands which contribute to semen and tubes forming sperm-carrying pathway. Ductus deferens, ejaculatory duct, prostate, seminal vesicle, bulbourethral

Inguinal canal

Opening in oblique musculature of abdominal wall. Bounded by medial superficial inguinal ring and lateral deep inguinal ring (weak point), prone to inguinal hernia.

cryptorchidism

One or both testes fail to descend from abdomen to scrotum. Sterile as body temp is too high for spermatogenesis.

interstitial Leydig cells

Located between seminiferous tubules, testosterone production controlled by luteinizing hormone.

testosterone functions

spermatogenesis, sperm maturation, maintains accessory sex organs, 2ndary sex characteristics, growth & metabolism, behavior & sex drive

Sertoli cells (sustenocytes)

Columnar cells line seminiferous tubules and facilitate spermiogenesis (structural) by providing nutrients to spermatids. Also forms blood-testis barrier and secrete regulatory substances.

seminiferous tubules

Looped inner network within the testes; site of sperm production. Spherical spermatogenic cells embedded in columnar sustenocytes. Thick germinal epithelium separated by areolar CT. 800 coiled tubules per testis.

Spermatogonia

Undergoes mitosis into A cells (remain precursors) and B cells, both diploid. B cells become primary spermatocytes (2n)

Spermatocytes

Primary spermatocytes (2n) undergo meiosis to become secondary spermatocytes (n).

Spermatogenesis

Production of germ cells, haploid gametes

Spermiogenesis

Structural maturation of spermatids into mature spermatozoa - growth of acrosome cap and flagellum/tail. Mitochondria gather to form midpiece, fructose powers tail. Occurs in seminiferous tubules supported by Sertoli cells.

blood testis barrier

Formed by tight junctions between Sertoli cells. Prevents immune attack on haploid sperm and maintains controlled environment for spermatogenesis.

Sertoli cell secretion

Androgen binding protein concentrates testosterone in tubules, Inhibin inhibits FSH release, testicular fluid transports sperm through tubules.

semen

1.5 - 5ml/ejaculate with 60-150 million sperm per mL. pH 7.2-7.8, 0-2000 leukocytes per mL, 1.5-6 mg fructose per mL. Maintains 60% motility 3 hrs after ejaculation. Sperm count less than 25 million per mL = oligospermia, infertility.

proximal root of penis

Unpaired bulb of corpus spongiosum surrounded by bulbocavernosus muscle and paired crura of corpora cavernosa attached to pubic arch by ischiocavernosus muscle.

glans penis

Termination of corpus spongiosum, surrounds external urethral orifice. Frenulum attaches prepuce (foreskin).

female 2ndary sex organs

Vagina, uterine tubes, uterus, mammary glands. Facilitate sperm reception, fertilization, offspring development, parturition, post-natal sustenance.

genital tubercle

develops into penis in males, clitoris in females

labioscrotal folds

develop into scrotum in males, labia majora in females

urethral folds

develop into scrotal raphe in males and labia minora + vestibule in females

paramesonephric or mullerian duct

Gives rise to uterus and uterine tubes in absence of testosterone

mesonephric or wolffian duct

Develops into epididymis, vas deferens, ejaculatory ducts in males in presence of TDF

hypospadia

Urethra opens downward from base of penis rather than tip

meiosis 1 - spermatogenesis

Diploid primary spermatocytes (from B cells) undergo meiosis to yield 2 haploid secondary spermatocytes.

meiosis 2 - spermatogenesis

2 haploid secondary spermatocytes undergo meiosis to yield 4 haploid spermatids.

congenital adrenal hyperplasia (CAH)

XX chromosomes, excess testosterone enlarges clitoris, virilizing external genitalia despite female chromosomal sex. Mullerian ducts present, Wolffian ducts absent.

androgen insensitivity syndrome

XY chromosomes, testosterone is produced but targets have no receptors, resulting in female genitalia despite male chromosomal sex. Mullerian duct absent due to AMH, wolffian duct absent due to no T

SRY gene on Y chromosome

Encodes testis-determining factor (TDF), causes differentiation of Sertoli cells to organize testis cords and initiate male dev.

Anti-Mullerian hormone (AMH)

Secreted by Sertoli cells, causes regression of paramesonephric/Mullerian ducts

XX

No AMH allows persistence of Mullerian duct, no testosterone regresses Wolffian ducts. External genitalia follow female dev.

myoid cells

Smooth muscle-like cells surrounding seminiferous tubules, propel developing sperm and fluid out of testes.

ovaries

Paired ova-producing primary sex organs enclosed in fibrous tunica albuginea. 3 cm x 1.5 cm x 1 cm, size decreases around menopause.

mesovarium

Fold of broad ligament which anchors the ovary

Uterine tube

Enclosed in mesosalpinx, lined with ciliated simple columnar epithelium and smooth muscle. Site of fertilization; scar tissue increases chance of ectopic pregnancy - failure of fetus to reach uterus.

Oogonia

Diploid stem cells giving rise to oocytes, degenerate after birth. Undergo mitosis to differentiate into primary oocytes (2n) which stall in meiosis 1 before birth.

Oocytes

2 million primary oocytes in primordial follicles at birth. By puberty, 400k remain. Loss occurs via atresia, degeneration

primordial follicle

Primary oocyte arrested in prophase 1 surrounded by a single layer of flattened follicular (pre-granulosa) cells

follicle stimulating hormone (FSH)

Stimulates growth of a cohort of follicles into primary oocytes each month by promoting oocyte growth and proliferation of follicular cells into stratified granulosa cells

secondary follicle

Follicular cells become stratified granulosa cells, zona pellucida forms around the oocyte, granulosa cells begin estrogen secretion.

Tertiary antral or Graafian follicle

Dominant follicle continuing development, others degenerate. Contains a primary oocyte before meiosis 1 completion.

secondary oocyte

Produced by oocyte completion of meiosis 1, along with first polar body. Meiosis 2 completes only if sperm penetrates and fertilizes, forms second polar body.

Tertiary or antral follicle structures

Large antrum with follicular fluid, central oocyte, zona pellucida surrounded by corona radiata.

zona pellucida

Glycoprotein coat around oocyte that sperm must penetrate to fertilize

corona radiata

Layer of estrogen-secreting granulosa cells surrounding zona pellucida. Remains attached to oocyte for metabolic support.

corpus luteum

Formed by follicle rupture for ovulation; granulosa and theca cells luteinize. Secretes progesterone and estrogen to maintain endometrium for implantation.

ovulation

Triggered by LH surge, stigma appears on ovarian surface, follicle wall ruptures. 2ndary oocyte, zona pellucida, corona radiata, and some granulosa cells released into peritoneal cavity.

Antrum

Cavity of tertiary follicle filled with follicular fluid that allows follicle expansion. Separates oocyte from follicle wall except at cumulus oophorus

cumulus oophorus

Mound of granulosa cells suspending oocyte within antrum and connecting it to follicle wall. Released with oocyte during ovulation.

uterine cycle

Menstrual (1-5) - functional layer sheds. Proliferative (6-14) - functional layer rebuilds (estrogen). Ovulation - day 14. Secretory (15-28) - endometrium prepares for embryo implantation (progesterone). premenstrual/luteal - part of secretory phase, E+P decline sharply.

mammary glands

Modified apocrine glands in both sexes, functional in lactating females. 15-20 lobes divided into lobules which contain alveoli. Simple cuboidal epithelium produces milk.