Medical Anatomy and Histology of Male vs Female Reproductive Organs [Biology, MCAT, USMLE] – Moosmosis

Female Reproductive System: Histology and Organs

• Medical Anatomy and Histology: Ovary
  • Squamous epithelium = primordial follicle
  • Cuboidal epithelium = primary follicle
  • Multi-layered cuboidal epithelium = multilaminar primary follicle
  • Antrum (fluid-filled space) in the follicle = secondary follicle
  • Pink band around the oocyte = zona pellucida
  • Theca cells sit outside of the basement membrane of the follicle
  • Corpus albicans = dissolving corpus luteum
  • Granulosa cells around the ovum in a maturing follicle = corona radiata
  • “Stalk” = cumulus oophorus
  • Dark pink, rubber-band-like structure inside = atretic follicle

• Medical Anatomy and Histology: Corpus Luteum
  • Granulosa cells are lighter staining
  • Darker staining fibroblastic cells are theca lutein cells
• Medical Anatomy and Histology: Ovary + Fallopian tube
  • Fallopian tube epithelium: tall nuclei close to the lumen (Peg cells)  and round nuclei (ciliated cells)
  • Ampulla has the most tortuous branching pattern; infundibulum has a smaller lumen w/ less branching; intramural portion is surrounded by some myometrial muscle

• Medical Anatomy and Histology: Uterus
  • In tact surface epithelium = not menstrual or immediately post-menstrual
  • Endometrium: basalis layer doesn’t change during menstrual cycle – functionalis layer does
  • Early proliferative phase: relatively smooth/straight glands in the functionalis +intact surface epithelium
  • Secretory phase: coiled glands with secretory product within them in the functionalis + intact surface epithelium + spiral arteries
  • Menstrual phase: hemorrhage + functionalis layer sloughing + edema

• Cervix: non-keratinized stratified squamous epithelium that transitions into simple columnar epithelium with glands
• Vagina: non-keratinized stratified squamous epithelium with washed-out looking cells (glycogen stored within them)
• Medical Anatomy and Histology: Placenta
  • Fetal side: large blood vessels and smooth, simple epithelium with two layers of extra-embryonic membranes
  • Villi within the placenta
    • Round with pale staining cytoplasm = cytotrophoblast
    • Continuous and dark staining cytoplasm = syncytiotrophoblast
    • Appearance depends on age (younger = more equal representation of cyto- and syncytiotrophoblast)
    • Fetal blood is within the villus; maternal blood is in the spaces around the villus
    • Macrophages w/in villi = Hofbauer cells
  • Decidua/decidual plate = maternal side = modified endometrium
  • A large villus that goes all the way across = stem/anchoring villus

• Medical Anatomy and Histology: Mammary Gland
  • Inactive mammary gland: “islands” of ductal tissue + dense irregular CT
  • Proliferative mammary gland: more glandular tissue than CT, development of secretory acini (little circles of cells), lumens haven’t gotten very large
  • Lactating mammary gland: dilated acini lumens w/ secretory product inside, more acini than ducts

Male Reproductive System: Organs and Histology

• Medical Anatomy and Histology: Testes
  • Seminiferous tubule
    • Pale staining nucleus + prominent nucleolus = Sertoli Cell
    • Small cells with dark nuclei on the BM = spermatogonia
    • Cells with condensed chromatin/mitotic figures = primary spermatocytes
    • Cells with a very round, condensed nucleus closer to the lumen = early spermatids
    • Cells will longer nuclei, starting to take on the appearance of sperm = late spermatids
  • Cells between the seminiferous tubules that produce testosterone = Leydig cells
  • Dense CT on the surface of the testis = tunica albuginea

• Efferent ductules: scalloped glands w/ alternating tall and short cells (have cilia – hard to see)
• Epididymis: smooth ductules, stereocilia, pseudostratified columnar epithelium
  • Mature sperm stored here – only goes to vas deferens pre-ejaculation.
  • Note the sperm that arrives at the epididymis is non-motile; the activation (capacitation) occurs here
  • Function of stereocilia is absorption of fluid that comes from the testes (to keep things moving along) – this concentrates the sperm

• Vas deferens: large smooth muscle wall (three layers), lined with pseudostratified columnar epithelium, basal cells, muscular wall much thicker than the diameter of the lumen
• Urethra: scalloped lumen with muscular wall (only 1-2x the thickness of the lumen), transitional epithelium (binucleate surface cells and multiplelayers)
• Seminal vesicle: convoluted lumen with mucosal crypts, seminal fluid in the lumen, pseudostratified columnar epithelium
• Prostate gland: prostatic concretions (laid down in layers, like tree rings), fibromuscular stroma
  • Don’t confuse with lactating mammary gland – the CT is very different
  • Note: older prostate has more concretions
• Medical Anatomy and Histology: Penis
  • Tunica albuginea: CT around the corpora cavernosa
  • Corpus spongiosum: penile urethra w/in

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