Animal Reproduction and Development

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primary sex characteristics: structures directly involved in reproduction, like the uterus and ovaries in feales, and the testes in males
Secondary sex chracteristics: include human features like body hair, distribution of muscle and fat, voice quality, and breats. In aniamls it can be deer antlers, lion manes, and peacock tails. They are used to indicate sexual maturity or sexual readiness and to attrract or locate mates, or are used by mates to compete for females
Ovary: the organ where ova, or eggs, are produced. Each female has two ovaries
ova: ovum, or eggs
oviduct: or fallopian tube, eggs move from the ovary to the uterus through the oviduct. There are two oviducts, one for each ovary
Uterus: a fertilized ovum implants (attaches) on the inside wall (endometrium) of this. Development of the embryo occurs here until birth
endometrium: the inside wall of the uterus
vagina: at birth, the fetus passes through the cervic and through this, and out of the body
cervix: opening in the uterus
Testis/ Testes: each one consists of seminiferous tubules and interstitial cells. The two are contained in a single sac which hangs outside the body
Seminiferous Tubules: in testis, for the production of sperm
Interstitial Cells: in testes, produces male sex hormomes, testosterone and other androgens
scrotum: contains the two testes and hangs outside of the body. It provides a temperature of about 2C below the body cavity which is essential for the development of sperm
Epididymis: this coiled tube, one attached to each testis, is the site for final maturation and storage of the sperm
vas deferens, vas deferentia: each of these two tubes transfers sperm from one epididymis to the uretha. Sperm exit the penis through the uretha
Seminal Vesicles: during ejaculation, these two glands secrete into the vas deferens mucus (which provides a liquid medium for the sperm), fructose (which provides energy) and prostaglandins (which stimulate uterine contractions that help sperm move into the uterus. All together this is called semen.
Prostate Gland: this gland secretes a milky alkaline fluid into the uretha and serves to neutralize the acidity of urine that may still be in the uretha, as well as the acidity of the vagina
Bulbourethral Glands: or Cowper's Glands, these two glands secrete a small amount of fluid of unknown function into the urethra
Penis: the urethra passes through this and serves to transport semen, teh fluid containing sperm and secretions, into the vagina. It also serves in the transport of urine out of the body
Sperm: compact packages of DNA specialized for the effective delivery of the male genome. They consist of a sperm head, a midpiece, and a tail
Sperm Head: this contains a haploid nucleus with 23 chromosomes in humans. At the tip of the head is the acrosome
acrosome: at the tip of the sperm head, a lysosome containing enzymes which are used to penetrate the egg. This originiates from the Golgi body vesicles that fuse to form a single lysosome.
Midpiece: in sperm, it is opposite the acrosome, the flagellum, consisting of the typical 9 and 2 microtubule array, emerges from the sperm head from one member of a pair of centrioles. The first part of the flagellum, the midpeice, is characterized by mitochondira that sprial around the flagellum and supply ATP for flagellar movement
Tail: of sperm, the remainder of the flagellum, behind the midpiece. Sperm are propelled by the whiplike motion of this and the midpiece
Gametogenesis: consists of the meiotic cell divisions that produce eggs in females and sperm in males
oogenesis: production of eggs
Oogonia: fetal cells that divide by mitosis to produce primary oocytes
primary oocytes: cells that begin meiosis. All of these progress only to porphase I where they remain at this stage until puberty, at which time one primary oocyte during each mentrual cycle continues its development through the remainder of meiosis I.
Follicle: envelope that encircles the developing oocyte and protects and nourishes it.
Secondary Oocyte: the one daughter cell of the primary oocyte that contians most of the cytoplasm (unequal cytokinesis) and the other daughter cell is a POLAR BODY with very little cytoplasm
Polar Body: daughter oocyte with very little cytoplasm that may continue with meiosis II and divide into two daughter polar bodies, but they ultimately disintegrate
unequal cytokinesis: assures that adequate amounts of stored food, as well as mitochondria, ribosomes, and other cytoplasmic organelles, will be available for the developing embryo
ovulation: marks the release of the secondary oocyte from the follicle. If it is fertilized by a sperm while it moves through the oviduct, the secondary oocyte will begin meiosis II and produce an egg that combines with the chromosomes contributed by the sperm. The second daughter cell of meiosis II, again a polar body, disintegrates
Spermatogenesis: begins at PUBERTY within the seminiferous tubules of the testes. Cells called spermatogonia devide by mitosis repeatedly to produce primary spermatocytes. The sperm continue their development in the epidymis, where they are stored until needed
Spermatogonia: cells that divide by mitosis repeatedly to produce primary spermatocytes
primary spermatocytes: products of spermatogonia that begin meiosis. Meiosis I produces two secondary permatocytes
secondary spermatocytes: at the end of meiosis II, become four spermatids
sertoli cells: in the seminiferous tubules, provides nourishment to the spermatids as they differentiate into SPERM
ovarian cycle: events in the ovary during the human demale reproduction cycle
menstrual cycle: events in the uterus that happen during the female repro. system
First Step of the Female Repro. Cycle: The hypothalamus and anterior pituitary initiate the reproductive cycle. The hypothalemus monitors teh levels of estrogen and progesterone in the blood. In a NEGATIVE FEEDBACK fashion, low levels of these hormones stimulate the hypothalamus to secrete GnRH, which, in turn, stimulates teh anterior pituitary to secrete FSH and LH
GnRH: gonadotropin releasing hormone from the hypothalamus
FSH: follicle stimulating hormone from the anterior pituitary
LH: luteinizing horomone from the anterior pituitary
estrogen and progesterone: from the follicle and corpus luteum
Second Step of the FRC: the follicle develops as FSH stimulates the development of the follicle and the egg
3rd Step of FRC: the follicle secretes estrogen which stimulates the secretion of estrogen from the follicle
4th step of FRC: ovulation occurs, POSITIVE FEEDBACK from rising levels of estrogen stimulate the anterior pituitary (through GnRH) to produce a sudden midcycle surge of LH which triggers ovulation
5th step of FRC: the corpus luteum secretes estrogen and progesterone, after ovulation, the follicle, now called the corpus luteum, continues to develop under teh influence of LH and secretes both estrogen and progesterone
6th step of FRC: the endometrium thickens, estrogen and progesterone stiumulate the development of the endometrium, the inside lining of the uterus. It thickens with nutrient rich tissue and blood vessels in preparation for implantation
7th step of FRC: The hypothalamus and anterior pituitary terminate the reproductive cycle, NEGATIVE FEEDBACK from the high levels of estrogen and progesterone cause the anterior pituitary (through the hypothalamus) to abate production of FSH and LH
8th step of FRC: The endometrium disintegrates, in the absence of FSH and LH, the corpus luteum deteriates. As a result, estrogen and progesterone production stops. Without estrogen and progesterone, the growth of the endometrium is no longer supported, and it disintegrates, sloughing off during menstruation.
9th step of FRC: the implanted embryo sustains teh endometrium, if implantation occurs, teh implanted embro secretes HUMAN CHORIONIC GONADOTROPIN (HCG) to sustain the corpus luterm, as a result, it will continue to produce estrogen and progesteron to maintain the endometrium. Later in development, HCG is replaced by progesterone secreted by the placenta
HCG: human chorionic gonadotropin, sustains endometrium at the beginning of the pregnancy and is what pregnancy tests look for
Follicular phase: of the ovarian cycle, the development of the egg and the secretion of estrogen from the follicle
Luteal phase: of ovulation, the secretion of estrogen and progesterone from the corpus luteum after ovulation
Interstitial cell stimulating hormone: LH in males
LH in males: stimulates the interstitial cells in the testes to produce testosterone and androgens
FSH in males: along with testosterone, Sertoli cells promote the development of sperm
Bryophyta: mosses, liverworts, hornworts: gametes produced in protective structures called gametangia, sperm swims through water, the diploid structure remains attached to the gametophyte. It lacks the specialized vasular tissues zylema nd phloem and does not have true roots, stems, or leaves. They must remain small and water must be readily available for absorption through surface tissues and as a transport medium for sperm
gametangia: protective structures of bryophyta that protect the gametes on the surface of the gametophytes (dominant haploid stage)
antheridium, antheridia: male gametangium of bryophyta that produces flagellated sperm that swim through water to fertilize the eggs produced by the female gametangium, or archegonium
Archegonium, archegonia: female gametangium of bryophyta
Tracheophytes: vasular plants that possess zylem and phloem and have true roots, stems, and leaves. Includes all but Bryophyta
Lycophyta, Sphenophyta, and Pterophyta: all produce sportes taht germinate into small gameophytes that produce antheridia and archegonia which produce sperm and eggs. ALl have flagellated sperm and fertilization leads to a diploid zygote which grows into the sporophyte which is the dominant generation
Lycophyta: includes the woody trees of the carboniferous period and tropical epiphytes.
Ephiphytes: group of lycophyta that live on other plans and small herbaceous plants. Includes club mosses because of their strobili
stobili: club shaped spore bearing cones of club mosses
Sphenophyta: tracheophyte that include extinct woody trees common during the carboniferous period and extant herbaceous plants called HORSETAILS
Horsetails: sphetophyta that have hollow, ribbed stems taht are jointed at NODES, the stems branches and leaves are green and photosynthetic and haev a rough texture tude to the presence of silica, stobili bear the spores
Nodes: of horsetaiols, occur at intervals along the stem and produce small, scalelike leaves and, in some species, branches
Pterophyta: Tracheophyte that are the FERNS. Clusters of sproangia called sori develop on the undersurface of fern fronds. Sporangia undero meiosis and produce the spores
Sori, sorus: clusters of sprorangia on the undersurface of fern fronds
Order of development from water to land: bryophyta, lycophyta, sphenophyta, pterophyta, coniferophyta, and anthophyta
metamorphosis: larva that undergo additional development that transform it into an adult.
fetus: an embryo that resembles the infant form
Embryonic Development: begins with the fertilization of the egg and continues until birth and is amazingly similar in almost all animal forms
Fertilization: occurs when the sperm penetrates teh plama membrane of the secondary oocyte. It is accompanied with recognition, penetration, formation of the fertilzation membrance, completion of meiosis II in the secondary oocyte, and fusion of nuclei and replication of DNA
Recognition: before penetration can occur, the sperm secretes a protein that binds with special receptor molecules that reside on a glycoprotein layer surrounding the plasma membrane of the oocyte. This vitelline layer or zona pellucida in humans insures that fertilization occurs only between egg and sperm of the same species
Vitelline layer: or zona pellucida in humans, insures that fertilization only occurs between egg and sperm of the same species during recognition
Penetration: the plasma mebrance of the sperm and oocyte fuse and the sperm nucleus enters the oocyte
formation of the fertilization membrane: the vitelline layer forms a fertilization membrane wchih blocks the entrance of additional sperm
completion of meiosis II in the secondary oocyte: In humans, sperm penetration triggers meiosis II in the oocyte, producing an ovum, and polar body. The polar body is discharged through the plasma membrane
Fusion of nuclei and replication of DNA: the sperm and ovum nuclei fuse, forming a zygote nucleus consisting of 23 pairs of chromosomes, in humans. Each chromosome replicates so that it consists of two idential chromatids
cleavage: the zygote now begins a series of these divisions, rapid cell divisions without cell growth. As a result each of the resulting cells, called blastomeres, contain substantially less cytoplasm that the original zygote. Some characteristics of early cleavage are embryo polarity, polar and equatorial cleavages, radial and sprial cleavages, and indererminate and determinate cleavages
blastomeres: resulting cells of cleavage divisions that have less cytoplasm than the original zygote
embryo polarity: the egg has an upper, animal pole, and lower, vegetal pole. Cells formed at the vegetal pole contain more yolk, or stored food, because the yolk material, denser than the surrounding cytoplasm, settles to the bottom of the egg
animal pole: upper end of the egg
Polar and Equatorial cleavages: early cleavages are polar, dividing the egg into segments that stretch from pole to pole like sections of an orange. Other cleavages are parallel with the equator (perpendicular to the polar cleavages)
radial and sprial cleavages: in DEUTETROSOMES, early cleavages are radial, forming cells at the animal and vegetal poles that are aligned together, the top cells directly above the bottom cells. In PROTOSOMES, clevages are spiral, forming cells on top that are shifted with respect to those below them.
Indeterminate and Determinate Clevages: a cleavage is indeterminate if it produces blastomeres that, if separated, can individually complete normal development. Determinate cleavage cells cannot develop into a complete embryo if separated from other blastomeres and instead their developmental program is limited to the production of definite or determined cells that contribute to only a part of the complete embryo. Radial cleavages of DEUTETEROSTOMES are usually indeterminate while sprial cleavages of PROTOSOMES are often determinate
Morula: successive cleavage divisions result in a SOLID BALL of cells
Blastula: as cell divisions continue, liquid fills the morula and pushes the cells out to form a CIRCULAR CAVITY surrounded by a SINGLE LAYER OF CELLS. The hollow sphere is this
Blastocoel: the cavity of the blastula
Gastrula: formation of this, also called gastrulation, occurs when a group of cells invaginate (move forward) into the blastula, forming a two layered embryo with an opening from the outside into a central cavity. There are three germ layers, an archenteron, and a blastopore
Three germ layers: a third cell layer forms between the outer and innder layers of the invaginated embryo called the ECTODERM (outside), MESODERM (middle), and ENDODERM (inside) layers and are the primary germ layers from which all subsequent tissues develop
Archenteron: center cavity formed by gastrulation. It is completely surroundede by endoderm cells
Blastopore: the opening into the archenteron that becomes the mouth in PROTOSOMES and the anus in DEUTEROSTOMES
Extraembryonic Membrane Development: includes the development of the chorion, allantois, amnion, and yolk sac in amniotes
amniotes: birds, reptiles, and humans
Chorion: outer membrane, in birds and reptiles it acts as a membrane for gas exchange and in humans it implants into the endometrium and forms the PLACENTA
placenta: a blend of maternal and embryonic tissues across whcih gases, nutrients, and wastes are exchanged
Allantois: begins as a sac that buds off from the archenteron. Eventually it encircles the embryo, forming a layer below the chorion. In birds and reptiles, it initially stores waste products in the form of uric acid. Later in development it fuses with the chorion and acts as a membrane for gas exchange with blood vessels below. IN mammales, it transports waste products to the placenta and forms the umbilical cord, transporting gases, nutrients, and wastes between the embryo and the placenta
Amnion: encloses the amniotic cavity, includes only humans, birds, and repiles
amniotic cavity: a fluid filled cavity that cushions the developing embryo much like the coelom cushions internal organs in coelomate animals
Yolk Sac: in birds and reptiles, the membrane of this digests the enclosed yolk. Blood vessels transfer the nutrients to the developing embryo. In placental mammals, it is empty and instead nutrition is obtained through the placenta
Organogensis: as cells continue to divide after gastrulation, they become different form oneanother (cell differentiation), taking on characteristics of specific tissues and organs. Chordates are noted for the notochord and the neural tube
notochord: in chordates, cells along the dorsal surface of the mesoderm germ layer form this, a stiff rod that provides support in lower chordates. The vertabrate of higher chordates is formed by nearby cells in the mesoderm
Neural Tube: in chordates, in the ectoderm layer directly above the notochord, a layer of cells forms the neural plate. It indents, forming a NEURAL GROOVE, then rolls up into a cylinder, the _______. It develops into the central nervous system and additional cells from the neural crest
neural crest: leftover ectoderm cells from the neural tube that form various tissues, including teeth, bones, and muscles of the cell, pigment cells in the skin, and other tissues
Ectoderm: epidermis of skin, lining of mouth and rectum, sense receptors, cornea and lens, nervous system, adrenal medulla, tooth entamel, epithelium of pineal and pituitary glands
Endoderm: epithelial lining of digestive tract, linging of respiratory system, liver, pancreas, thyroid, parathyroids, thymus, lining of urethra, urinary bladder, and reproductive system
Mesoderm: notochord, skeletal system, muscular system, ciruculatory and lymphatic systems, excretory system, reproductive system, dermins of skin, lining of body cavity, and adrenal cortex
Frog, amphibian: has a grey crecent, gastulation with a dorsal lip, and a yolk

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