Chapter 29 AI Generated

Comprehensive vocabulary flashcards covering fertilization, embryonic and fetal development, maternal physiological adaptations, labor, neonatal adjustments, and lactation from Chapter 29.

Gametes

Sex cells produced by organisms to generate offspring, specifically sperm (spermatozoa) in males and secondary oocytes in females.

Gonads

The organs that produce gametes, specifically the testes in males and the ovaries in females.

Pregnancy

A sequence of events that begins with fertilization, proceeds to implantation, embryonic development, and fetal development, and ideally ends with birth about $38\,\text{weeks}$ later, or $40\,\text{weeks}$ after the mother's last menstrual period.

Developmental biology

The study of the sequence of events from the fertilization of a secondary oocyte by a sperm cell to the formation of an adult organism.

Embryo

The developing human from fertilization through the eighth week of development during the embryonic period.

Fetus

The developing human during the fetal period, which begins at week nine of development and continues until birth.

Prenatal development

The time from fertilization to birth, encompassing both the embryonic and fetal periods, divided into three trimesters.

First trimester

The most critical stage of prenatal development during which all major organ systems begin to form and the developing organism is most vulnerable to drugs, radiation, and microbes.

Second trimester

The stage of prenatal development characterized by nearly complete development of organ systems, by the end of which the fetus assumes distinctively human features.

Third trimester

The stage representing rapid fetal growth where the weight of the fetus doubles and most organ systems become fully functional.

Fertilization

The process occurring in the uterine tube within $12\text{ to }24\,\text{hours}$ after ovulation wherein genetic material from a haploid sperm cell and a haploid secondary oocyte merges into a single diploid nucleus.

Capacitation

A series of functional changes lasting about $7\,\text{hours}$ in the female reproductive tract that causes a sperm's tail to beat more vigorously and removes membrane cholesterol and proteins to prepare its membrane for fusion.

Corona radiata

The outermost layer of granulosa cells surrounding the ovulated secondary oocyte that a sperm must penetrate for fertilization.

Zona pellucida

The clear glycoprotein layer located between the corona radiata and the oocyte's plasma membrane.

Acrosome

A helmetlike structure covering the head of a sperm cell that contains enzymes necessary for penetrating the corona radiata and zona pellucida.

ZP3

A specific glycoprotein in the zona pellucida that acts as a sperm receptor, triggering the acrosomal reaction when bound by membrane proteins in the sperm head.

Acrosomal reaction

The release of enzyme contents from the acrosome of a sperm cell to digest a pathway through the zona pellucida.

Polyspermy

The fertilization of a secondary oocyte by more than one sperm cell.

Fast block to polyspermy

The rapid electrical depolarization of the oocyte cell membrane occurring within seconds of sperm fusion, preventing attachment of additional sperm.

Slow block to polyspermy

The hardening of the entire zona pellucida and inactivation of ZP3 caused by calcium-triggered exocytosis of secretory vesicles from the oocyte.

Male pronucleus

The nucleus that develops from the nucleus inside the head of the fertilizing sperm cell within the ovum.

Female pronucleus

The nucleus that develops from the nucleus of the fertilized ovum once the secondary oocyte completes meiosis II.

Syngamy

The fusion of the haploid male and female pronuclei, which produces a single diploid nucleus with $46$ chromosomes.

Zygote

The single diploid fertilized ovum resulting from the fusion of the male and female pronuclei.

Dizygotic (fraternal) twins

Twins produced by the independent release of two secondary oocytes and their subsequent fertilization by two distinct sperm cells.

Monozygotic (identical) twins

Twins that develop from a single fertilized ovum through the separation of developing cells into two embryos, occurring before $8\,\text{days}$ in $99\%$ of cases.

Conjoined twins

Twins that are physically joined together and share body structures, resulting from embryonic cell separations that occur later than $8\,\text{days}$ after fertilization.

Cleavage

The rapid sequence of mitotic cell divisions of the zygote that begins approximately $24\,\text{hours}$ after fertilization.

Blastomeres

The progressively smaller individual cells produced by mitotic cleavage divisions of the early embryo.

Morula

A solid sphere of cells still enclosed by the zona pellucida, formed by successive cleavages by day $3\text{ or }4$ and roughly the same size as the original zygote.

Uterine milk

A glycogen-rich secretion from endometrial glands that enters the morula through the zona pellucida on day $4\text{ or }5$ to supply nutrients.

Blastocyst cavity (blastocoel)

The fluid-filled internal cavity that forms around the $32\text{-cell}$ stage, reorganizing the blastomeres.

Blastocyst

The hollow developmental stage composed of hundreds of cells enclosing a blastocyst cavity, differentiated into an embryoblast and a trophoblast.

Embryoblast

The inner cell mass located internally within the blastocyst that eventually develops into the embryo.

Trophoblast

The outer superficial spherelike wall of the blastocyst that develops into the chorionic sac and the fetal portion of the placenta.

Implantation

The attachment of the blastocyst to the vascular, glandular endometrial lining of the uterus, initiating loosely about $6\,\text{days}$ after fertilization.

Decidua

The modified functional layer of the endometrium following implantation, which separates from the uterus after delivery.

Decidua basalis

The portion of the endometrium between the embryo and the stratum basale of the uterus that provides nutrients and becomes the maternal part of the placenta.

Decidua capsularis

The portion of the endometrium situated between the embryo and the uterine cavity that bulges, fuses with the decidua parietalis, and degenerates by about $27\,\text{weeks}$.

Decidua parietalis

The remaining modified endometrium that lines the noninvolved regions of the rest of the uterus during pregnancy.

Syncytiotrophoblast

The outer layer of the trophoblast lacking distinct cell boundaries that secretes enzymes to digest endometrial cells and secretes human chorionic gonadotropin.

Human chorionic gonadotropin (hCG)

A hormone produced by the trophoblast and chorion that rescues the corpus luteum from degeneration and maintains progesterone and estrogen production.

Amniotic cavity

A fluid-filled space that appears within the epiblast around day $8$ of development and enlarges over the embryonic disc.

Amnion

A thin, domelike protective membrane of squamous cells forming the roof of the amniotic cavity that eventually encloses the entire embryo.

Amniotic fluid

Fluid initially derived from maternal blood and later supplemented by fetal urine that acts as a shock absorber, prevents desiccation, and regulates fetal temperature.

Amniocentesis

A clinical procedure involving the withdrawal and diagnostic analysis of amniotic fluid and sloughed fetal cells.

Exocoelomic membrane

A thin membrane formed by migrating hypoblast cells that lines the inner surface of the blastocyst wall and forms the wall of the yolk sac.

Yolk sac

An extraembryonic membrane formed by the hypoblast and exocoelomic membrane that produces early blood cells, houses primordial germ cells, and forms part of the gut.

Lacunae

Small spaces that develop within the expanding syncytiotrophoblast on day $9$ and subsequently interconnect into lacunar networks.

Maternal sinusoids

Dilated endometrial capillaries surrounding the developing embryo that are eroded to allow maternal blood to enter the lacunar networks.

Extraembryonic mesoderm

A mesenchyme connective tissue layer derived from the yolk sac that surrounds the amnion and yolk sac, forming the connective foundation for the chorion.

Chorion

The extraembryonic membrane formed by the extraembryonic mesoderm and two trophoblast layers, serving as the principal embryonic part of the placenta.

Connecting (body) stalk

A band of extraembryonic mesoderm that connects the bilaminar embryonic disc to the trophoblast and ultimately becomes the umbilical cord.

Gastrulation

The major developmental process occurring about $15\,\text{days}$ after fertilization that converts the bilaminar embryonic disc into a trilaminar embryonic disc.

Primitive streak

A faint groove on the dorsal surface of the epiblast extending from posterior to anterior that establishes the embryo's body axes and bilateral symmetry.

Invagination

The inward migration and detachment of epiblast cells beneath the primitive streak during gastrulation.

Endoderm

The primary germ layer formed by invaginating epiblast cells that displace the hypoblast, giving rise to the epithelial lining of the gastrointestinal and respiratory tracts.

Mesoderm

The primary germ layer formed between epiblast and newly formed endoderm, giving rise to muscles, bones, other connective tissues, and the peritoneum.

Ectoderm

The primary germ layer formed by remaining epiblast cells, developing into the nervous system and the epidermis of the skin.

Notochordal process

A hollow midline tube of mesodermal cells formed about $16\,\text{days}$ after fertilization by cells migrating from the primitive node toward the head end.

Notochord

A solid cylinder of cells formed by days $22\text{ to }24$ that plays a critical role in induction, stimulates vertebral body development, and becomes the nucleus pulposus.

Induction

The process by which an inducing tissue stimulates the developmental specialization of an adjacent responding tissue, typically via chemical signaling.

Neural plate

A thickened band of ectodermal cells induced by the notochord during the third week of development to initiate formation of the nervous system.

Neural tube

A hollow cylindrical structure formed by the fusion of neural folds whose cells develop directly into the brain and spinal cord.

Neurulation

The developmental process involving the formation of the neural plate, neural folds, and their fusion into the neural tube.

Neural crest

Migrating ectodermal cells from the neural tube that give rise to sensory and postganglionic neurons, adrenal medullae, melanocytes, and head connective tissues.

Chorionic villi

Fingerlike projections of the chorion that contain fetal capillaries and extend into the maternal endometrial wall.

Intervillous spaces

Maternal blood spaces formed from united lacunae that bathe chorionic villi with maternal blood without mixing maternal and fetal blood cells.

Placentation

The developmental process of forming the placenta, the organ responsible for nutrient, waste, and gas exchange between mother and fetus.

Placenta

A pancake-shaped organ formed by the chorionic villi (fetal portion) and decidua basalis (maternal portion) that exchanges substances and produces pregnancy hormones.

Umbilical cord

The vascular structure connecting placenta and fetus, measuring about $2\,\text{cm}$ wide and $50\text{ to }60\,\text{cm}$ long, containing two umbilical arteries and one umbilical vein.

Wharton's jelly

Supporting mucous connective tissue derived from the allantois that surrounds the blood vessels within the umbilical cord.

Afterbirth

The placenta and attached fetal membranes after they detach and are expelled from the uterus following childbirth.

Umbilicus (navel)

The abdominal scar formed where the severed remnant of the umbilical cord withers and detaches $12\text{ to }15\,\text{days}$ after birth.

Vernix caseosa

A protective fatty mixture of oil gland secretions and dead epithelial cells that coats the skin of the fetus.

Lanugo

Delicate, fine hair covering the body of the fetus visible during weeks $17\text{ to }20$ of pregnancy.

Quickening

The first fetal movements commonly perceived by the mother, typically occurring between $17$ and $20\,\text{weeks}$ of gestation.

Relaxin

A hormone produced by the corpus luteum and placenta that increases the flexibility of pelvic joints and aids in dilating the uterine cervix during labor.

Human chorionic somatomammotropin (hCS)

A placental hormone, also termed human placental lactogen (hPL), that alters maternal metabolism to free fatty acids and spare glucose for fetal growth.

Corticotropin-releasing hormone (CRH)

A placental hormone that establishes the timing of birth and triggers fetal cortisol secretion required for lung maturation and surfactant synthesis.

Chloasma

Increased skin pigmentation appearing in a masklike pattern around the eyes and cheekbones during pregnancy.

Linea nigra

A darkened line of pigmentation along the linea alba of the lower abdomen that develops during pregnancy.

Striae

Stretch marks that develop over the abdomen as the uterus enlarges during pregnancy.

Parturition

The physiological process by which the fetus is expelled from the uterus through the vagina; commonly termed labor or giving birth.

Stage of dilation

The initial stage of true labor, typically lasting $6\text{ to }12\,\text{hours}$, extending from labor onset to the complete dilation of the cervix to $10\,\text{cm}$.

Stage of expulsion

The second stage of labor, lasting from complete cervical dilation ($10\,\text{cm}$) through the delivery of the baby.

Placental stage

The stage of labor lasting $5\text{ to }30\,\text{minutes}$ or more after delivery where uterine contractions expel the placenta and constrict torn blood vessels.

Puerperium

The $6\text{-week}$ postpartum period during which maternal reproductive organs and physiological systems return to their prepregnancy state.

Involution

The marked reduction in the size of the uterus back toward its nonpregnant state via tissue catabolism during the puerperium.

Lochia

A postpartum uterine discharge lasting $2\text{ to }4\,\text{weeks}$, consisting initially of blood and later of serous fluid from the former placental site.

Fossa ovalis

The permanent depression in the interatrial septum of the heart formed by the fusion and closure of the fetal foramen ovale at birth.

Ductus arteriosus

A fetal vessel connecting the pulmonary trunk to the aorta that shunts blood away from nonfunctional fetal lungs, closing after birth.

Ligamentum arteriosum

The fibrous cord remnant formed when the fetal ductus arteriosus completely closes and atrophies after birth.

Bradykinin

A polypeptide released by the lungs during their initial inflation at birth that mediates smooth muscle contraction to shut off the ductus arteriosus.

Ductus venosus

A fetal blood vessel connecting the umbilical vein directly with the inferior vena cava, allowing oxygenated placental blood to bypass the fetal liver.

Ligamentum venosum

The fibrous cord remnant in the liver resulting from the collapse and closure of the fetal ductus venosus after birth.

Lactation

The production and ejection of milk from the mammary glands.

Prolactin (PRL)

An anterior pituitary hormone that acts as the principal promoter of milk production in the mammary glands once estrogen and progesterone levels drop.

Milk ejection (let-down)

A positive feedback neuroendocrine reflex wherein oxytocin stimulates contraction of myoepithelial cells, propelling milk from alveoli into mammary ducts.

Colostrum

A cloudy fluid secreted by the mammary glands during late pregnancy and early postpartum days containing maternal antibodies, less lactose, and virtually no fat.