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261 Cards in this Set
- Front
- Back
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what is embryology?
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the study of growth and differentiation of an organism from a single fertilized cell to a complex and indepent being like its parents.
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what changes does embryology study?
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the changes which organisms undergo during their development
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what is prenatal period?
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before birth where development proceeds rapidly with more drastic morphological changes
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what is postnatal period?
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the period of development after birth where changes take place more gradually and are followed by aging.
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what is the pre-embryonic period?
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the period of development of the gametes (gametogenesis), their fusion, cleavage, blastulatoin, gastrulation, and up to implantation
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what is the embryonic period
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the period from implantation to the origin of the primordia of the organs and the formation of the basic body form.
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what is fetal period?
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the period of growth and maturation of hte organ-system to become competent to assume their specialized functions.
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define embryo
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the developing offspring during the embryonic period
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define fetus
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the developing offspring during the fetal period
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what is the term conceptus used to describe?
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the embryo/ fetus and its membranes
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what is tertology
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study of malformations (abnormalities)
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what is the theory of recapitulation?
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an individual in its develpement passes through a series of constructive stages like those in the evolutionary development of the race to which it belong.
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what is ontogeny?
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an individuals complete life history, fertilization to death
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what is phylogeny
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ancesteral history of an organism, evolutionary development
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what is the pre-formation theory?
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sperm or ovum contained the new individual in miniature form
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what is epigenetic theory?
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the development that occurs through progressive growth and differentiation through a series of causal interaction between various parts
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who gave the foundation of the knowledge of germ layers?
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van baer
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what is one area where embryology can assist with human medicine?
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advancement of science by offering area of fertilty research, embryo transfer, in vivo fertilization, stem cell research, cloning, etc.
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what is gametogenesis
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production of gametes, ie. spermatozoa in male and ovum in female
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____ cells give rise to gametes
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germ cells
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define gametogenesis
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the process by which germplasm are converted into highly specialized sex cells (gametes) that are capable of uniting at fertilization and producing a new being.
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where does the origin of primodial germ cells occur?
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originated in the wall of the yolk sac, where they migrate and get established in the developing gonad.
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what are primoidal cells?
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they are cells destined to become gametes
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where does the development of sperm take place?
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in the testis after puberty
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what happens to type A spermatogonia?
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stem cell
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what happens to type B spermatogonia?
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spermatogonia proceed in spermatogenesis and replicate its DNA in interphase of its cell cycle to form primary spermatocytes
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what stage is DNA replication in to form primary spermatocytes?
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interphase
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how many meiotic divisions do primary spermatocytes undergo?
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two
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what happens in the first meitoic division of the primary spermatocyte?
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the chromosomes are evenly distributed and each member of a homologous pair goes into one of the daughter cells. This is called reductive division.
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what is a secondary spermatocyte?
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the resulting products of the first meiotic division
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what happens when the secondary spermatocyte undergoes a seond division?
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one member of the homologous pair is now split into two; one going into each of the daughter cells. This is called equal division
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what are the products of the second division of secondary spermatocytes?
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products= spermatids
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during spermeogenesis, spermatids undergo some metamorphosis to form highly differentiated and potentially motile cells called?
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spermatozoa
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during spermeogenesis, the chromatin content of the nucleus becomes concentrated and forms ?
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the head of the sperm
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during spermiogenesis, the golgi apparatus becomes concentrated and reorganized to form the?
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acrosomal cap
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during spermiogenesis, the centriole moves away from the anterior end taking on the shape of the ring to encircle the?
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flagellum
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The mitochondria become concentrated around the proximal part of the flagellum which from the ?
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middle piece of the spermatozoa
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what is semen composed of?
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sperm and secretions from the accessory sex gland
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In most mammals spermatogenesis is believed to last ____-___ days and another __-___ weeks for passage through the epididymis?
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50-70 days
2-3 weeks |
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In the ovary of the female fetus, each primordial germ cell form ____ which are mitotically active up to parturition.
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oogonium
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what is tertology
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study of malformations (abnormalities)
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what is the theory of recapitulation?
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an individual in its develpement passes through a series of constructive stages like those in the evolutionary development of the race to which it belong.
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what is ontogeny?
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an individuals complete life history, fertilization to death
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what is phylogeny
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ancesteral history of an organism, evolutionary development
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what is the pre-formation theory?
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sperm or ovum contained the new individual in miniature form
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what is epigenetic theory?
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the development that occurs through progressive growth and differentiation through a series of causal interaction between various parts
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who gave the foundation of the knowledge of germ layers?
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van baer
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what is one area where embryology can assist with human medicine?
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advancement of science by offering area of fertilty research, embryo transfer, in vivo fertilization, stem cell research, cloning, etc.
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what is gametogenesis
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production of gametes, ie. spermatozoa in male and ovum in female
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____ cells give rise to gametes
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germ cells
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In which stage of DNA replication does the oogonium replicate its DNA?
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in interphase
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After the oogonium replicates its DNA, the next cycle is?
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prophase of the first meiotic division
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after the first meiotic divison, the female germ cells are now called?
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primary oocyte
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The first meiotic division of oogonium is arrested in the ____ stage of prophase I and will not resume until puberty.
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diplotene
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At birth, all primary oocyte are in the ____ stage of prophase I
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diplotene
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The first meiotic division of the oogonium leads to the formation of ____ cells
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2 daughter cells
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what are the two daugher cells after the first meiotic division of oogonium?
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secondary oocyte and first polar body
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the genetic material of daugher cells is ___ divided, but cytokinesis is ___ during the division
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equally divided
unequally divided |
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the daughter cell that receives most of the ___ is the secondary oocyte
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cytoplasm
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the other daughter cell that receives much less cytoplasm is called the?
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first polar body
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When can a secondary oocyte complete its second meitoic division ?"
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after the stimulus of the penetration of sperm
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what are the products of the second meiotic division of oogonium?
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ovum and a second polar body
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In most animals, the secondary oocyte must be penetrated by ___ before the second meiotic division is completed.
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penetrated by spermatozoa
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In the horse and dog the ___ oocyte resting in prophase is ovulated and ___ meiotic division occur after the penetration of sperm
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primary oocyte
both meiotic divisions |
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define fertilization
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the fusion of the sperm and ovum to initiate the development of a new individual
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Fertilization is preceeded by what two things?
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1. ovulation
2. Insemination |
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define ovulation
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the release of primary or secondary oocytes from the surface of the ovary
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define insemination
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the deposisiton of sperm into the female genital tract.
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what are the two ways insemination can occur?
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naturally- coitus
artifically- AI |
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what is ovulation controlled by
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FSH follicular stimulating hormone and LH lutenizing hormone
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what are ruptured follicles converted into?
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the corpus luteum after hormonal influence
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what does the corpus luteum secrete?
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progesterone
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what does progesterone do to the uterine lining
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faciliates the implantation and maintenance of the conceptus
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ovulation is spontaneous in most animals except the ___ and ___
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rabbit and cat
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cats and rabbits ovulation is induced by the ___. These animals are called ____ ovulators
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coitus
induced ovulators |
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what does polytocous mean?
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more than one oocyte is set free usually from seperate follicles
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what does monotocous mean?
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one oocyte is set free during each period
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what are examples of polyocous animals?
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bitch, sow, cat, and small ruminant
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what are examples of polytocous animals?
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cow, horse, llama
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the ovulated egg is received at the ___ end of the oviduct through a constant stream of ____ fluid which enters the uterine tube. It is transported toward the uterus through ____ movement and ___ contraction of the uterine tube.
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fimbriated end (abdominal ostium)
peritoneal fluid cilary movement and muscular contraction |
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At insemination, ____ of male ___ cells or ___ are deposited in the vagina.
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millions of male germ cells or spermatozoa
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how is transport of sperm achieved?
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by the muscular contraction of the cervix and uterus and by motility of the sperm themselves
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In most species, sperm are viable within the female genital tract for ___-___ days?
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1-2 days
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Sperm are viable in the female genital tract of horses and dogs for ___-___ days
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6-7
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sperm are viable in the female fowl for up to ___ days
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32
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sperm are viable in the female turkey for up to __ days.
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70
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how do sperm survive for so long in female birds?
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they have a sperm host gland
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how long is ovum viability usually?
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24 hours
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where does fertilization usually occur in the uterine tube? and how long does it take ? where does it occur in dogs?
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in the ampullary region. 12-24 hours after ovulation
dogs- infundibulum of the uterine tube |
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what must spermatozoa undergo in order to fertilize the oocyte?
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the process of capacitation and acrosomal reaction
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what does capacitation involve?
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removal of glycoprotein coat and seminal plasma protein from the plasma membranes that overlies the acrosomal region of the spermatozoa
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what does acrosomal reaction involve?
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release of enzymes (hyaluronidase and trypsin like substances) The action of the enzymes facilitate the penetration of the oocyte barriers
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what are oocyte barriers?
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corona radita, zona pellucida, and oocyte cell membrane
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what are the results of sperm penetration?
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2nd meitoic division completed
fertilization reaction zona reaction female and male pronuclei zygote |
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what is the fertilization reaction?
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develops which prevent the further entry of sperm into the oocyte
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what is the zona reaction
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chemical changes in the zona pellucida that prevent further sperm entry
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what are female and male pronuclei?
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female and male germ cells swell
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what happens after the female and male pronuclei swell?
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they fuse and form a zygote
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what happens prior to fusion of the pronuclei?
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the pronuclei duplicate their DNA content and immediately on fusion of their chromosomes split in the course of a normal mitotic division, resulting in a 2-cell zygote
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what is determined as a result of fertilization?
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determination of sex, XX female XY male, reverse in birds
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how are monozygous twins created?
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when one ovum is fertilized but subsequently divides at the blastocyst stage into two genetically identical masses, therefore always the same sex and blood group.
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how are dizygous twins created?
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when two seperate ova are fertilized .
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what happens during ectopic implantation?
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a fertilized ovum may be lost in the peritoneal cavity and become implanted into the peritoneal surface. Early embryonic death usually follows
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what happens in freemartin?
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in dizygous twinning in cattle, the development of a common circulation by placental anatomosis usually occurs
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what happens in freemartin if the twins are opposite sex?
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the development of the genital system is retarded in the female embryo under the influence of testosterone produced by the male embryo
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what is freemartin?
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the female is born infertile
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what is polyspermy?
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when more than one sperm may penetrate the female germ cell.
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In what animal does polyspermy occur in commonly?
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the pig
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what happens usually in polyspermy?
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the great majority of the conceptus die at a very early stage of development
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what is superfecundation
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impregnation by successive acts of coitus, or two or more ovum that were liberated at approximately the same time by two or more different males
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in what animals does superfecundation occur?
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cats and dogs
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what is superfetation?
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whne a pregnant female ovulates, conceive, and produce a second younger fetus. eg. pigs
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what is cleavage?
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the beginning of the development of a multicellular organism
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what causes cleavage?
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a series of mitotic cell divisions without overall increase in the size of the zygote, which is still enveloped by zona pellucida
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what are blastomeres?
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many smaller cells resulting from teh segmentation or fractionation division of cleavage
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where does the first division of cleavage occur?
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the long axis of the cytoplasm
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what is the second division of cleavage?
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tends to be at the right angles to the previous one
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what is the speed of division (cleavage) inversely proportional to?
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the amount of yolk present
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what is total or holoblastic cleavage?
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in mammals where a small amount of yolk is present and equally distributed (Isolecithal egg). There is a complete division of the zygote. Thus the cleavage is total or holoblastic
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what is partial or meroblastic cleavage?
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in birds, the massive amount of yolk (polylecithal egg) prevent complete division of hte zygote
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what is a morula?
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after 4 to 6 divisions, the zygote results in the formation of a solid cluster of cells
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in man, the morula consists of how many cells? in how many days?
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16 cells by the fourth day of development
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in domestic animals, the morula consists of how many cells?
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16-64
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what is the blastocoel?
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the secretion form the blastomeres colected within the morula, causing rupture of the zona pellicuda and formation of a fluid filled cavity
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what is the embryo known as when its a blasocoel?
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a blastocyst
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all the cells of the blastocyst are not ____
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identical
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what constitutes the embryonic disc?
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those in one small area becomes larger than the rest of the cells constitute the embryonic disc or inner cell mass or blastodisc from which the embryo will develop
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what are trophoblast cells?
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the cells on the periphery of the blastocyst.
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what do trophoblast cells do?
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facilitate in the absorption of nutrients early in development
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the embryonic disc (inner cell mass) becomes rearranged to form?
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germ layers
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what are the three germ layers?
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ectoderm (outermost), endoderm (in the middle), and mesoderm (inner layer)
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what is the gestation period for a mare?
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335-345 days
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what is the gestastion period for a cow?
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279-282 days
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what is the gestation period for a ewe?
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148-150 days
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what isthe gestation period for a sow?
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114-120 days
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what is the gestation period for a bitch?
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60-65 days
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what is the gestation period for a queen?
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60 days
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what forms the endoderm?
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a group of cells from inner cell mass (embryonic disc) become detached from its inner surface to form a new continuous sheet lining the interior of the blastocyst
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what is the cavity enclosed in the newly formed endoderm?
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primitive gut or archetreron
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what is the process of detachment of the cells from the inner cell mass called?
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delamination
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what forms the ectoderm?
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the cells in the upper layer of the inner cell mass undergo considerable expansion and form the ectoderm
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when does the covering of the trophoblast cells over the embryonic ectoderm disappear?
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when the ectoderm is formed
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how is the primitive streak formed?
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most of the cells between the ectoderm and endoderm converge toward the midline
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the primitive streak lies in the future___ ___ of the embryo?
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longitudial axis
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what does the cranial end of the primitive streak enlarge and become?
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the primitive or Hensen's node
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the primitive streak serves as a center of ____ proliferation and gives rise to ____ cells
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cellular proliferation
mesodermal cells |
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how is the mesoderm formed?
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when the cells from the primitive streak undergo rapid proliferation and invaginate between the ectoderm and endoderm layers
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what forms the endoderm?
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a group of cells from inner cell mass (embryonic disc) become detached from its inner surface to form a new continuous sheet lining the interior of the blastocyst
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what is the cavity enclosed in the newly formed endoderm?
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primitive gut or archetreron
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what is the process of detachment of the cells from the inner cell mass called?
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delamination
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what forms the ectoderm?
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the cells in the upper layer of the inner cell mass undergo considerable expansion and form the ectoderm
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when does the covering of the trophoblast cells over the embryonic ectoderm disappear?
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when the ectoderm is formed
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how is the primitive streak formed?
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most of the cells between the ectoderm and endoderm converge toward the midline
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the primitive streak lies in the future___ ___ of the embryo?
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longitudial axis
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what does the cranial end of the primitive streak enlarge and become?
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the primitive or Hensen's node
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the primitive streak serves as a center of ____ proliferation and gives rise to ____ cells
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cellular proliferation
mesodermal cells |
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how is the mesoderm formed?
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when the cells from the primitive streak undergo rapid proliferation and invaginate between the ectoderm and endoderm layers
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what forms the endoderm?
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a group of cells from inner cell mass (embryonic disc) become detached from its inner surface to form a new continuous sheet lining the interior of the blastocyst
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what is the cavity enclosed in the newly formed endoderm?
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primitive gut or archetreron
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what is the process of detachment of the cells from the inner cell mass called?
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delamination
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what forms the ectoderm?
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the cells in the upper layer of the inner cell mass undergo considerable expansion and form the ectoderm
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when does the covering of the trophoblast cells over the embryonic ectoderm disappear?
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when the ectoderm is formed
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how is the primitive streak formed?
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most of the cells between the ectoderm and endoderm converge toward the midline
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the primitive streak lies in the future___ ___ of the embryo?
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longitudial axis
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what does the cranial end of the primitive streak enlarge and become?
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the primitive or Hensen's node
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the primitive streak serves as a center of ____ proliferation and gives rise to ____ cells
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cellular proliferation
mesodermal cells |
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how is the mesoderm formed?
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when the cells from the primitive streak undergo rapid proliferation and invaginate between the ectoderm and endoderm layers
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the primitive node contributes to the formation fo the head ____ as well as the ____
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head mesoderm
notochord |
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the notochord induces the ectoderm to from the ____ ectoderm (also known as)
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neural ectoderm
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Later, the notochord regresses and persists in the adult as the ____ ___ of the intervertebral disc.
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nucleus pulposus
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the dorsally proliferating cells from the primitive streak, aranged on either side of the notochord, become thickened to form the ____ _____
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paraxial mesoderm
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the laterally proliferating cells from the primitive streak, form the ____ ____ aka ___ ____
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lateral plate
lateral mesoderm |
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what is the junction between the paraxial mesoderm and lateral mesoderm is called the?
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intermediate mesoderm
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the lateral mesoderm split into two layers ____ and ____ mesoderm.
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somatic and splanchnic mesoderm
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what is the space between the splanchnic and somatic mesoderm called?
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coelom
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the somatic mesoderm is associated with the ectoderm to from the
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somatopleure
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the splanchnic mesoderm is associated with endoderm to form the ?
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splanchnopleure
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paraxial mesoderm later forms a series of mesodermal thickenings called ____
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somites
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early somite subsequently differentiates into three ___, ____, and ____.
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myotomes, dermatome, and scleratome
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somites constitute ____ (sclerotome), its associated _____ (myotomes), and ____ (dermatome)
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vertebral column - scleratome
muscles- myotomes connective tissues- dermatome |
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the part of the germ layer which underlies the embryonic disc is called ___-____ ____ layer whereas the cells lying peripherally under the trophoblast are called the _____ ___ layer
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intra-embryonic germ layer
extraembryonic germ layer |
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____ ectoderm-> epidermis, including cutaneous glands, hair, nails and lens of the eye; Epitelium of sense organ, nasal cavity, sinuses; mouth including oral glands, enamal, and anal canal.
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surface ectoderm
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____ ectoderm-> nervous tissue including hypophysis, adrenal medulla and retina of the eye
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neural ectoderm
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_____ mesoderm-> vertebral column and its associated muscles and connective tissue
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paraxial mesoderm
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____ mesoderm-> kidneys, adrenal cortex, gonads, and genital ducts
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intermediate
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____ mesoderm-> cardiovascular and lymphatic system, pleura and peritoneum, spleen, muscles, and connective tissue
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lateral mesoderm
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the pharnyx, root of tongue, audiory tube, larynx, trachea, lungs, digsestive tube including glands, bladder, urethra, and associate glands are all derivates of?
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endoderm
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in the establishment of the body form, the most important aspect is the transformation of ____ disc into roughly ___ ____ embryo
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flat disc
roughly curved cylindrical embryo |
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the embryo establishes a body form by ____ folding and ___ folding.
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longitudinal folding and transverse or lateral folding of embryonic disc
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The ___ folding of the embryo is in cephalo-caudal direction?
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longitudinal
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longitudinal folding is more pronounced in the ___ and ____ end of the embryo, thus head and tail fold are formed.
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cranial and caudal end of the embryo
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the ____ folding of embryonic disc obtains a cylindrical appearance and lateral and ventral body wall of the embryo is established
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transverse or lateral folding
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The embryonic disc is converted from a flat-disc into a ___ __ strucuture
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curved cylindrical structure
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the extraembryonic germ layers develop into ____ or ____ membranes and surround the cylindrical embryo.
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extraembryonic or fetal membranes
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the lateral and ventral body walls develop the folding of the ____ _____
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intraembryonic somatopleure
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the extraembryonic somatopleure constitute the ___ and ___
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amnion and chorion
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the gut is formed by the _____ splanchnopleure
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intraembryonic
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the yolk sac and allontois are formed by the _____ splanchnopleure
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extraembryonic
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the yolk sac communicates with the gut through _____ duct or ____ stalk
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vitellointestinal duct or yolk stalk
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the unclosed area of the ventral surface of the embryo at the junction of embryonic and extraembryonic territories constitute the ______ ___
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umbilical cord
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The ____ ____ contains yolk sac with vitelline blood vessels and allantois with its allantois or umbilical blood vessels
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umbilical cord
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the early age of the embryo is expressed by the number of ____, later ___-____ length us used to determine the appoximate age of the embryo
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somites
crown-rump (CR) length |
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amnion develops from the _____ somatopleure which gradually overgrow the embryo and fuse together
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extraembryonic
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fluid accumulates in the amniotic cavity and form ____ ___ sac around the embryo
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fluid filled sac
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____ is excess amount of amniotic fluid
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hydroamnion
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the ___ is the outermost membrane, develops from the _____ somatopleure
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chorion
extraembryonic somatopleure |
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the finger-like projection called ___ ___ develop over the surface of the chorion, to make contact with the uterus of the mother
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chorionic villi
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chorion fuses with allantois to form ___-____ placenta
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chorio-allantoic placenta
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the yolk sac develops from the _____ splanchnopleure
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extra-embryonic
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in most mammals, the yolk sac develops to form temporary contact with chorion, termed ____ placenta, which regresses immediately, but remain functional for sometime (first quarter of prego) in dog and horses
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choriovitelline placenta
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well developed in birds and develop blood vessels, termed ___ vessels, absorb the nutrition of the yolk sac.
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vitelline
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the allontois develops from the ____ splanchnopleure as the ____ of the hindgut
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extraembryonic splanchnopleure
diverticulum |
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the ___ is a reseroir for excretory products of the fetus
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allantois
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___ fuses with the chorion to develop the chorio-allantoic placenta
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chorion
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the blood vessels that develop in the allantois are termed ____ vessels
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umbilical vessels
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a free-living blastocyst is nourised by the secretion from _____ glands. later, it develops fetal membranes and attach the the ___ endothelium and establish a close relationship between fetal and maternal circulatory system. This process is called ____
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endometrial
implantation |
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___ or ___ implantation is when the embryonic sac lies in the uterine lumen or cavity.
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superficial or central
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what types of animals have superficial or central implantation?
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ruminants, equines, or porcine
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____ implantation is when the embryonic sac lies in a fold or pocket of uterine wall
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eccentric implantation
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what types of animals have eccentric implantation?
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rat and squirrel
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____ implantation is when the embryonic sac penetrates and is embedded into the uterine wall
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interstital
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what types of animals does interstital implantation occur ?
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guinea pig, carnivores, bats, and man
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how long does implantation take for a sow
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13-14 days
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how long does implantation take for a bitch
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17-18 days
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how long does implantation take for a queen
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13-14 days
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how long does implantation take for an ewe?
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15-20 days
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how long does implantation take for a cow?
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25-30 days
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how long does implantation take for a mare?
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35-40 days
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the composite structure fromed by the close contact of fetal membranes and maternal tissue for the purpose of physiological exchange between fetus and mother is termed?
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placenta
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nutrients and oxygen from the maternal blood diffuses from the uterine ___ the the umbilical ___
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uterine artery umbilical vein
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excretory products from the embryo diffuse from umbilical ____ into the uterine ___
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umbilical artery uterine vein
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what are the 5 functions of the placenta?
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nutrition, respiration through gaseous exchange, excretion, barrier (impermeable to bacteria) and synthesis of hormones
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____ placentation is when the yolk sac may combine with the chorion to form choriovitelline placenta e.g. in horse and dog, first quarter of gestation, later the yolk sac regresses
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choriovitelline or yolk sac placentation
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what type of placentation is whenthe allantois fuses with the chorion and allontochoion is formed. This is the most common type in domestic animals, pig, ruminant, carn.
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chorioallantoic placentation
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the ____ shaped placenta has chorionic villi that are uniformly distributed over the entire sac.
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diffuse
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what types of animals have diffuse plancenta?
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sow and mare
sow has folds to increase surface area for feto-maternal exchange |
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the ___ shaped placentahas tufts of chorionic villi (cotyledons) attach to maternal (caruncle) structures to form placentomes
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cotyledonary
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what animals have cotyledonary placentas?
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ruminants
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the ___ shaped placenta has chorionic villi that form a band around the chorionc sac
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zonary
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what animals have zonary placenta's?
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carnivores
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the ___ shaped placenta has chorionic villie that from one or two disc-shaped area
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discoidal
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what animals have discoidal placenta's
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primates, rodents, bats
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___ braching occurs when there is a simple branching of chorionic villi
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villous
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what animals have villous branching of their chorionic villi?
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mare and ruminats
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___ branching occurs when there is complicated and anastomitic branching of the chorionic villi?
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labyrinthine branching
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what animal have labyrinthine branching of chorionic villi
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carnivores and primates
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___ is an extensive loss of maternal tissue that occur at partrition, due to complicated interlocking of fetal and materal tissue?
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deciduate
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what animals have deciduate loss during partiturtion?
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carnivores and primates
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____ is little loss of maternal tissue occur due to relatively simple feto-maternal contact.
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nondecidutate
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what animals have nondeciduate loss during parturition?
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sow, mare, and ruminants
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how many layers are there seperating the fetal blood from the maternal blood histologically?
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6
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what are the three histogical layers on the fetal side seperating fetal from maternal blood?
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chorionic (villous) epithelium, fetal connective tissue, and endothelium of the allantoic blood vessels
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what are the three histological layers on the maternal side of seperating the fetal and maternal blood?
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uterine epithelium, uterine connective tissue, and endothelium of the blood vessel of uterus
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____ : chorionic epithelium is in contact with uterine epithelium. All six layers are present, e.g. sow and mare
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epitheliochorial
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____: chorionic epithelium is in contact with uterine connective tissue. Five layers are present. eg. ruminants
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syndesmochorial
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______: chorionic epithelium is in contact iwth the endothelium of hte uterine blood vessels. Four laryers are present e.g. carnivores
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endotheliochorial
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_____: the chorionic epithelium is in contact with the uterine blood. Only three layers are present, e.g. primate
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hemochorial
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___ is the branch of embryology that is concerned with the study of malformations
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teratology
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_____ mutations occur because of dominant or recessive genes, imbreeding may produce
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genetic
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what are the 4 types of environmental teratogens?
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physical (xrays)
chemical agents (vit. a def. ) drugs- (thalidominde in pups) infectious agents- panleukopenia virus in kittns |
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what period is most suseptible in developing teratological issues?
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embryonic
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