Reproductive Biomedical Embryology, Anatomy, Physiology, and Pathology Flashcards

Comprehensive vocabulary flashcards covering human reproductive embryology, anatomy, histology, physiology, and pathology based on the provided notes.

Surface Ectoderm

The external germ layer that gives rise to the epidermis, adenohypophysis (from Rathke pouch), lens of the eye, epithelial linings of the oral cavity, sensory organs of the ear, olfactory epithelium, anal canal above the pectinate line, and parotid, sweat, and mammary glands.

Craniopharyngioma

A benign Rathke pouch tumor derived from surface ectoderm that presents with cholesterol crystals and calcifications.

Neural Tube

Neuroectoderm derivative that gives rise to the brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina, and spinal cord.

Neural Crest

Ectodermal derivative that gives rise to enterochromaffin cells, melanocytes, odontoblasts, PNS ganglia (cranial, dorsal root, autonomic), adrenal medulla, Schwann cells, spiral membrane (aorticopulmonary septum), endocardial cushions, and skull bones.

MOTEL PASSES Mnemonic

A mnemonic for Neural Crest derivatives: Melanocytes, Odontoblasts, Thyroid C cells, Enterochromaffin cells, Laryngeal cartilage, PNS ganglia, Adrenal medulla, Schwann cells, Spiral membrane, Endocardial cushions, and Skull bones.

Mesoderm

The middle germ layer that gives rise to muscle, bone, connective tissue, serous linings of body cavities, spleen, cardiovascular structures, lymphatics, blood, wall of gut tube, proximal vagina, kidneys, adrenal cortex, dermis, testes, ovaries, microglia, and tracheal cartilage.

Notochord Postnatal Derivative

A mesodermal structure that induces ectoderm to form neuroectoderm (neural plate); its only postnatal derivative is the nucleus pulposus of the intervertebral disc.

VACTERL Association

A constellation of mesodermal defects consisting of Vertebral defects, Anal atresia, Cardiac defects, Tracheo-esophageal fistula, Renal defects, and Limb defects (bone and muscle).

Endoderm

The internal germ layer that gives rise to gut tube epithelium, most of the urethra and distal vagina (from urogenital sinus), and luminal epithelial derivatives such as lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, and thyroid follicular and parafollicular cells.

Developmental Events of Week 0

Fertilization occurs in the ampulla, sperm undergoes capacitation (removes glycoprotein and acrosome), and hyaluronidase breaks down hyaluronic acid protecting the egg.

Developmental Events of Week 1

Human chorionic gonadotropin ($\text{hCG}$) secretion begins when the blastocyst implants in the endometrium (around day $20$ of the menstrual cycle); the blastocyst sticks on day $6$.

Developmental Events of Week 2

Formation of the bilaminar disc ($2$ layers: Epiblast and Hypoblast); the amniotic cavity appears between trophoblast and embryoblast; embryoblast becomes the bilaminar disc; trophoblast becomes the placental side; hypoblast becomes the yolk sac with vitelline fluid.

Developmental Events of Week 3

Gastrulation and formation of the trilaminar disc; epiblast invaginates through the primitive streak to form endoderm, mesoderm, and ectoderm; notochord induces ectoderm to become neural plate and form neural tube; primitive gut tube starts.

Developmental Events of Week 4

Heart begins to beat and cardiac activity becomes visible; upper and lower limb buds begin to form; cloaca divides into urogenital sinus and rectal canal; tracheoesophageal ridges divide into trachea and esophagus.

Developmental Events of Week 7

Sex chromosomes start to develop, and the pancreatic buds fuse.

Developmental Events of Week 8

Germ cells migrate from the yolk sac toward the gonadal ridge; genitalia acquire male or female characteristics from primitive sex cords dividing into mesonephric (Wolffian) duct for males or paramesonephric (Müllerian) duct for females.

Gestational Age vs. Embryonic Age

Gestational age is calculated from the date of the last menstrual cycle, whereas embryonic age is calculated from the date of conception (gestational age minus $2\,\text{weeks}$).

Vitamin A Excess Teratogenicity

Causes mutations in Homeobox ($\text{Hox}$) genes, leading to spontaneous abortion and birth defects such as cleft palate and cardiac defects.

Iodine Deficiency Teratogenicity

Causes cretinism, characterized by severe congenital hypothyroidism.

Iodine Excess Teratogenicity

Causes congenital goiter in the developing fetus.

Methylmercury Toxicity

Neurotoxic substance found in large fish (swordfish, tilefish, mackerel) that adversely affects fetal development.

Folate Deficiency Teratogenicity

Causes neural tube defects in week $4$ of embryonic development; prevented by supplementing with a minimum of $1\,\text{g}$ of folate.

Sonic Hedgehog (SHH) Gene

Produced at the notochord and limb buds (zone of polarizing activity); involved in CNS development and anterior-posterior limb axis patterning; mutations lead to holoprosencephaly.

Wnt-7 Gene

Produced at limb buds (apical ectodermal ridge); controls dorsal-ventral limb axis patterning.

Fibroblast Growth Factor (FGF) Gene

Produced at limb buds (apical ectodermal ridge); stimulates proximal-distal limb outgrowth.

Homeobox (HOX) Genes

Produced at multiple locations; responsible for the segmental organization of the embryo in the cranial-caudal axis; mutations lead to limb malformations.

Pharyngeal Clefts

Structure of the pharyngeal apparatus derived from ectoderm, also called pharyngeal grooves.

Pharyngeal Arches

Structure of the pharyngeal apparatus derived from mesoderm (muscles, arteries) and neural crest (bones, cartilage).

Pharyngeal Pouches

Structure of the pharyngeal apparatus derived from endoderm.

1st Pharyngeal Cleft Derivative

Develops into the external auditory meatus.

2nd through 4th Pharyngeal Clefts

Form temporary cervical sinuses that are normally obliterated by the proliferation of 2nd arch mesenchyme.

Pharyngeal Cleft Cyst

A lateral neck mass anterior to the sternocleidomastoid muscle caused by a persistent cervical sinus; does not move with swallowing.

1st Pharyngeal Pouch Derivatives

Contributes to endoderm-lined structures of the ear, including the middle ear cavity, Eustachian tube, and mastoid air cells.

2nd Pharyngeal Pouch Derivative

Forms the epithelial lining of the palatine tonsils.

3rd Pharyngeal Pouch Derivatives

Dorsal wings form the inferior parathyroids, and ventral wings form the thymus.

4th Pharyngeal Pouch Derivatives

Dorsal wings form the superior parathyroids, and ventral wings form the ultimopharyngeal body, which gives rise to parafollicular (C) cells of the thyroid.

1st Pharyngeal Arch

Innervated by $\text{CN V}_3$; muscles include muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, and anterior $2/3$ of tongue; cartilage forms maxillary process (maxilla, zygomatic bone) and mandibular process (Meckel cartilage $\rightarrow$ mandible, malleus, incus, sphenomandibular ligament).

2nd Pharyngeal Arch

Innervated by $\text{CN VII}$; muscles include muscles of facial expression, stapedius, stylohyoid, and posterior belly of digastric; Reichert cartilage forms stapes, styloid process, lesser horn of hyoid, and stylohyoid ligament.

3rd Pharyngeal Arch

Innervated by $\text{CN IX}$; muscles include stylopharyngeus; cartilage forms the greater horn of the hyoid.

4th and 6th Pharyngeal Arches

4th arch innervated by $\text{CN X}$ (superior laryngeal) for pharyngeal constrictors, cricothyroid, levator veli palatini; 6th arch innervated by $\text{CN X}$ (recurrent laryngeal) for intrinsic laryngeal muscles except cricothyroid; cartilages form arytenoids, cricoid, corniculate, cuneiform, and thyroid.

SRY Gene

Gene located on the Y chromosome that stimulates testis formation from primitive sex cords.

Male Germ Cells

Testicular cell type that produces male gametes (sperm) during puberty.

Sertoli Cells

Testicular cell type that secretes Anti-Müllerian Hormone (AMH), causing degeneration of Müllerian (paramesonephric) ducts.

Leydig Cells

Testicular cell type that produces testosterone at Week $8$ (stimulated by LH), driving Wolffian duct development and converting to DHT via $5\alpha\text{-reductase}$.

Mesonephric Duct Derivatives

Structures formed from the Wolffian duct under testosterone stimulation: Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens (SEED).

DHT Male Derivatives

Structures formed when testosterone converts to DHT via $5\alpha\text{-reductase}$: Penis, Scrotum, and Prostate (PSP).

Testes Descent Timeline

Testes pass through the inguinal canal at around the $28\text{th}$ week of gestation and reach the scrotum at around the $33\text{rd}$ week.

Testicular Arteries Origin

Bilateral arteries arising from the abdominal aorta at the level of $\text{L2-L3}$, just inferior to the renal arteries.

Right Testicular Artery Pathway

Arises from aorta at $\text{L2-L3}$, passes inferolaterally over psoas major, lies anterior to the IVC, crosses in front of genitofemoral nerve and ureter, and enters deep inguinal ring.

Left Testicular Artery Pathway

Arises from aorta at $\text{L2-L3}$, passes inferolaterally over psoas major, lies posterior to the inferior mesenteric vein and descending colon, crosses genitofemoral nerve and ureter, and enters deep inguinal ring.

Scrotal Ligament

The adult remnant of the gubernaculum in males.

Female Germ Cells

Ovarian cell type that produces oogonia.

Granulosa Cells

Ovarian cell type that synthesizes estrogen; functional equivalent to male Sertoli cells.

Theca Cells

Ovarian cell type that synthesizes progesterone (and produces androgens stimulated by LH); functional equivalent to male Leydig cells.

Female Gubernaculum Derivatives

Remnants form the ovarian ligament and the round ligament of the uterus.

Paramesonephric Duct Derivatives

Structures formed in females in the absence of testosterone and AMH: Fallopian tubes, Uterus, and Proximal vagina (FUP).

Urogenital Sinus (Female)

Endodermal structure that develops into the urethral and vaginal openings, Bartholin glands, and Skene glands.

Gubernaculum

Band of fibrous tissue that guides and anchors the gonads during embryonic descent.

Processus Vaginalis

Evagination of peritoneum assisting gonadal descent; forms tunica vaginalis in males and obliterates completely in females.

Cryptorchidism (Embryological)

Failure of one or both testes to descend into the scrotum, increasing the risk of infertility and testicular cancer.

Hydrocele (Embryological)

Accumulation of fluid in the tunica vaginalis resulting from incomplete closure of the processus vaginalis.

Indirect Inguinal Hernia (Embryological)

Hernia occurring when the processus vaginalis remains patent, allowing abdominal contents to enter the inguinal canal lateral to inferior epigastric vessels.

Genital Tubercle Homologs

Forms the glans penis, corpus cavernosum, and spongiosum in males (via DHT) and the clitoris and vestibular bulbs in females (via Estrogen).

Urogenital Sinus Homologs

Forms bulbourethral (Cowper) glands and prostate in males (via DHT) and Bartholin glands and Skene glands in females (via Estrogen).

Urogenital Folds Homologs

Forms the ventral shaft of penis and terminal urethra in males (via DHT) and the labia minora in females (via Estrogen).

Labioscrotal Swelling Homologs

Forms the scrotum in males (via DHT) and the labia majora in females (via Estrogen).

Cytotrophoblast

The inner layer of chorionic villi that creates new cells.

Syncytiotrophoblast

The outer layer of chorionic villi that synthesizes and secretes $\text{hCG}$; lacks MHC I expression to reduce maternal immune attack.

hCG Detection Timeline

Detectable in maternal blood tests $1\,\text{week}$ after fertilization and in urine tests $2\,\text{weeks}$ after fertilization.

Decidua Basalis

Maternal placental component derived from the endometrium where maternal blood enters lacunae via endometrial arteries and veins.

Amniotic Fluid Composition and Clearance

Derived mainly from fetal urine and fetal lung fluid; cleared by fetal swallowing and intramembranous absorption.

Polyhydramnios

Excess amniotic fluid caused by fetal inability to swallow (e.g., esophageal/duodenal atresia, anencephaly), maternal diabetes, fetal anemia, or multifetal gestation.

Oligohydramnios

Insufficient amniotic fluid caused by placental insufficiency, bilateral renal agenesis, or posterior urethral valves.

Potter Sequence

Syndrome resulting from severe oligohydramnios characterized by lung hypoplasia, limb deformities, and a flattened face.

Placental Transfer of IgG

Immunoglobulin G is the only maternal antibody class that crosses the placenta, providing passive immunity to the fetus.

Allantois

Endodermal invagination that forms the primordial bladder and early umbilical cord; regresses to form the urachus.

Umbilical Arteries

Two vessels carrying deoxygenated blood from fetal internal iliac arteries to the placenta; regress into medial umbilical ligaments.

Umbilical Vein

Single vessel delivering oxygenated blood from the placenta to the fetus via liver/ductus venosus to IVC; supported by Wharton's jelly.

Urachus Pathologies

Anomalies due to incomplete urachus regression, including Patent urachus (urine discharge from umbilicus), Urachal cyst (fluid-filled cavity), and Vesicourachal diverticulum (bladder outpouching).

Vitelline Duct Pathologies

Incomplete obliteration of omphalomesenteric duct by Week $7$ causing Vitelline fistula (meconium discharge from umbilicus) or Meckel diverticulum (ileal outpouching in $2\%$ of population).

Human Chorionic Gonadotropin (hCG) Subunits

Composed of an $\alpha\text{-subunit}$ identical to LH, FSH, and TSH, and a $\beta\text{-subunit}$ unique to hCG (target of pregnancy tests).

Elevated hCG Conditions

Multiple gestations, hydatidiform moles, choriocarcinomas, and Down syndrome (trisomy $21$).

Decreased hCG Conditions

Ectopic or failing pregnancies, Edwards syndrome (trisomy $18$), and Patau syndrome (trisomy $13$).

Human Placental Lactogen (hPL)

Hormone secreted by syncytiotrophoblasts that stimulates maternal insulin production, induces maternal insulin resistance and lipolysis, preserving glucose and amino acids for the fetus.

Mitosis

Somatic cell division producing $2$ genetically identical diploid daughter cells with $46$ chromosomes ($23$ pairs) through stages: Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.

Meiosis

Gamete cell division producing $4$ genetically diverse haploid daughter cells with $23$ chromosomes, featuring crossing over in Prophase I and two nuclear divisions.

Histones

Positively charged proteins rich in lysine and arginine around which negatively charged DNA wraps.

Nucleosome

The fundamental subunit of chromatin, described as "beads on a string," consisting of DNA wrapped around histone proteins.

Mitochondrial DNA

Circular DNA structure that does not utilize histones.

Mammary Lines Development

Arise at Week $7$ as epidermal bands from forelimb to hindlimb; regress except in the thoracic region where sprouts form $16\text{-}24$ small buds.

Lactiferous Ducts Embryology

Formed by canalization of mammary buds by the end of intrauterine life, opening into an epithelial pit that transforms into the nipple.

Pubertal Breast Development

Estrogen and progesterone stimulate lactiferous ducts to form alveoli and secretory cells.

Polythelia

Accessory nipples resulting from remnants of mammary lines that failed to regress along the mammary ridge pathway.

Breast Lobes and Lobules

Each breast contains $12\text{-}20$ lobes made of lobules, which contain alveoli (acini cells) and mammary secretory cells.

Lactiferous Sinuses

Small reservoirs where milk collects from lactiferous ducts before being released through the nipple.

Myoepithelial Cells (Breast)

Contractile cells surrounding breast lobules and alveoli that contract under oxytocin stimulation to eject milk.

Breast Lymphatic Drainage

Lymph drains primarily into axillary lymph nodes, serving as a primary route for breast cancer metastasis.

Nonkeratinized Stratified Squamous Epithelium

Protective epithelium found in areas subject to abrasion: vagina, oral cavity, anal area, and skin.

Squamocolumnar Junction

The transformation zone between the ectocervix (stratified squamous) and endocervix (simple columnar); undergoes metaplasia and is the primary site for cervical cancer and HPV $16/18$ dysplasia.

Simple Columnar Epithelium

Secretory lining found in glandular tissues, including the endometrium of the uterus and fallopian tubes.