Chapter 35 Vocab
Asexual Reproduction
Form of reproduction in which offspring arise from only one parent
Sexual Reproduction
The combination of genetic material from two individuals to create a third individual
Gamete
A sex cell; sperm or egg cell
Sperm Cells
Male gamete
Egg Cell
Female gamete
Fertilization
The union of two gametes
Zygote
Fused egg and sperm; develops into a diploid individual
External Fertilization
Release of gametes by males and females into the same environment; fertilization occurs outside the body
Internal Fertilization
Use of a copulatory organ to deposit sperm inside a female’s body
Differentiation
Process by which cells acquire specialized functions
Pattern Formation
Developmental process that establishes the body’s overall shape and structure
Indirect Development
Development of a juvenile animal into an adult while passing through intervening larval stages
Metamorphosis
Developmental process in which an animal changes drastically in body form during the transition between juvenile and adult
Larva
Immature stage of animal development; does not resemble the adult of the species
Direct Development
Development pattern in which a juvenile animal resembles an adult
Reproductive System
Organ system consisting of organs that produce and transport gametes and that may nurture developing offspring
Gonad
Gland that manufactures hormones and gametes in animals; ovary or testis
Germ Cell
Specialized cell that gives rise to gametes
Secondary Sex Characteristic
Trait that distinguishes the sexes but does not participate directly in reproduction
Testis
Male gonad; organ that produces sperm and hormones
Scrotum
The sac containing the testes
Epididymis
tube that receives and stores sperm from one testis
Vas Deferens
Tube that transports sperm from an epididymis to an ejaculatory duct
Ejaculatory Duct
Tube that deposits sperm into the urethra
Urethra
Tube that transports urine (and semen in males) out of the body
PENIS
Cylindrical male organ of copulation and urination
Semen
Fluid that carries sperm cells out of the body
Seminal Vesicle
structure that contributes fluid, fructose, and prostaglandins to semen
Prostate Gland
Male structure between the bladder and the penis; produces a milky, alkaline fluid that activates sperm
Bulbourethral Gland
Small, mucus-secreting gland near the male urethra
Orgasm
Pleasurable sensation, accompanied by involuntary muscle contractions, associated with sexual activity
Ejaculation
Discharge of semen through the penis
Spermatogenesis
The production of sperm
Seminiferous Tubule
Tubule within a testis where sperm form and mature
Sertoli Cell
Cell that supports developing sperm cells within a seminiferous tubule
Interstitial Cell
Testosterone-secreting endocrine cell in a testis
Spermatogonium
Diploid germ cell in the wall of a seminiferous tubule; divides mitotically to yield a stem cell and a primary spermatocyte
Primary Spermatocyte
Diploid cell arising from a spermatogonium; undergoes meiosis I and yields two haploid secondary spermatocytes
Secondary Spermatocyte
Haploid cell that undergoes meiosis II and yields two haploid spermatids
Spermatid
One of four haploid cells produced in meiosis II of spermatogenesis
Spermatozoon (pl. Spermatozoa)
Mature sperm cell
Acrosome
Structure covering the head of a sperm cell, containing enzymes that enable the sperm to penetrate layers around the oocyte
Gonadotropin-Releasing Hormone (GnRH)
Reproductive hormone produced in the hypothalamus in both sexes; stimulates the release of FSH and LH from the anterior pituitary
Follicle-Stimulating Hormone (FSH)
Hormone produced in the anterior pituitary; stimulates secretion of sex hormones in both sexes
Luteinizing Hormone (LH)
Reproductive hormone produced in the anterior pituitary; stimulates secretion of sex hormones in both sexes
Testosterone
Steroid sex hormone produced primarily in the testes of male vertebrates
Follicle Cell
Nourishing cell surrounding an oocyte
Uterine Tube (Fallopian Tubes or Oviducts)
Tube that conducts an oocyte from an ovary to the uterus
Uterus
Muscular, saclike organ where embryo and fetus develop
Endometrium
Inner uterine lining that is shed during menstruation and supports an embryo during pregnancy
Menstruation
Discharge of the endometrium through the vagina during a menstrual period
Vagina
Conduit from the uterus to the outside of the body; receives the penis during intercourse; the birth canal
Clitoris
Small, highly sensitive female sexual organ at the junction of the labia
Breast
Milk-producing organ in female mammals
Vulva
External female genitalia; the labia, clitoris, and vaginal opening
Oogenesis
The production of egg cells
Oogonium
Diploid germ cell in an ovary; divides mitotically to yield two primary oocytes
Primary Oocyte
Diploid cell arising from an oogonium; undergoes meiosis I and yields a haploid polar body and a haploid secondary oocyte
Secondary Oocyte
Haploid cell that undergoes meiosis II and yields a haploid polar body and a haploid egg cell
Polar Body
Small, haploid byproduct of female meiosis; typically cannot be fertilized
Ovulation
Release of an oocyte from an ovarian follicle
Corpus Luteum
Gland formed from a ruptured ovarian follicle that has recently released an oocyte
Ovarian Cycle
Hormonal cycle that controls the timing of oocyte maturation in the ovaries
Menstrual Cycle
Hormonal cycle that prepares the uterus for pregnancy
Estrogen
Steroid sex hormone produced in ovaries of female vertebrates
Progesterone
Steroid sex hormone produced in ovaries of female vertebrates
Contraception
Use of devices or practices that prevent pregnancy
Sexually Transmitted Infection STI
Infection caused by a virus, bacterium, protist, or fungus that spreads during sexual contact
Preembryonic Stage
First 2 weeks of human development
Cleavage
Period of rapid cell division following fertilization
Morula
Preembryonic stage consisting of a solid ball of cells
Blastocyst
Preembryonic stage consisting of a fluid-filled ball of cells; develops into the embryo and part of the placenta
Inner Cell Mass
Cells in the blastocyst that develop into the embryo
Implantation
Embedding of the blastocyst into the uterine lining
Human Chorionic Gonadotropin (hCG)
Hormone secreted by the trophoblast and the placenta; indirectly prevents menstruation
Embryonic Disc
In the preembryo, a flattened, two-layered mass of cells that develops into the embryo
Extoderm
Outermost germ layer in an animal embryo; develops into skin and nervous system
Endoderm
Innermost germ layer in an animal embryo; develops into lining of digestive tract and other internal organs
Mesoderm
Embryonic germ layer between ectoderm and endoderm in an animal embryo; develops into muscles, bones, the circulatory system, and several other structures
Gastrula
Early animal embryo consisting of two (cnidarians) or three (other animals) tissue layers
Embryonic Stage
Stage of human development lasting from the end of the second week until the end of the eighth week of gestation
Allantois
Extraembryonic membrane that manufactures blood cells and gives rise to the umbilical cord’s blood vessels
Yolk Sac
Extraembryonic membrane that forms beneath the embryonic disc and manufactures blood cells that support an early embryo
Amnion
Protective extraembryonic membrane that contains amniotic fluid surrounding an embryo or fetus
Chorion
Outermost extraembryonic membrane; helps establish the placenta
Chorionic Villus (pl. villi)
Fingerlike projection extending from the chorion to the uterine lining; site of exchange between a woman’s blood and a fetus
Placenta
Structure that connects the developing fetus to the maternal circulation in placental mammals
Umbilical Cord
Ropelike structure containing blood vessels that connect an embryo or fetus with the placenta
Primitive Streak
Furrow along the back of the embryonic disc in the third week of human development; longitudinal axis around which later structures develop
Notochord
Flexible rod extending along a chordate’s back; one of the four characteristics of chordates
Neural Tube
Embryonic precursor of the central nervous system
Fetal Stage
Stage of human development lasting from the beginning of the ninth week of gestation through birth
Birth Defect
Abnormality that causes death or disability in a newborn