E1Trans2 Flashcards
Analysis of similarities and differences in development, provides insight that ontogeny recapitulates phylogeny
Comparative embryology
Accounts on the processes and sequential events of development, step by step account
Descriptive embryology
State the Recapitulation Theory
The development of an individual organism summarizes the development of its species. Ontogeny recaps phylogeny.
Von Baer’s law
General features appear earlier in development while specific features appear later.
Stage wherein different species appear almost identical
Phylotypic stage (stage 1)
Oviparous
Eggs develop outside mother
Viviparous
Embryo develops inside mother
Ovoviviparous
Eggs retained in mother’s body until birth
Causative factors in development, testing hypotheses by manipulating embryo
Experimental embryology
Pioneer of experimental embryology
Wilhelm Roux
Studies problems on conception and contraception
Reproductive biology
Emphasis of reproductive biology
Normal gametogenesis Transport of gametes and fertilization Reproductive endocrinology Early embryonic development Transplantation of mammalian embryo
Study of interaction chemical and physical events in development
Chemical embryology
Study of birth defects, malformations due to endogenous and exogenous factors
Teratology
Main stages in histological development
Proliferation, migration, differentiation
Genetic defects in teratology
Mutations, aneuploidy, translocation
Fetal alcohol syndrome
Malformations due to lack of cell proliferation
Phocomelia
Severely deficient or malformed limbs due to genetic inheritance, mutations, or thalidomide
Phoco - seal, melia- limb
Who cloned Dolly? Where?
Ian Wilmut and Keith Campbell at the Roslin Institute
The process of creating genetically identical animals
Animal cloning
Posed the question “how are different parts of a developing embryo formed?”
Aristotle
Defined preformation
Aristotle
What is preformation?
A miniature embryo is enclosed in the germ cell and requires only time and nourishment for it to develop.
What is epigenesis?
The gradual formation of new structures and organs. From a single cell arises a multicellular organism.
Spermists believe that…
Sperm cell contains an individual, ovum merely nourishes it
A tiny human (____) in fetal position at head of sperm
Encasement concept, homunculus
Ovists believe that…
Ovum contains the fetus, stimulated to grow by seminal fluid
Who strengthened the ovist belief? How?
Charles Bonnet, upon discovering parthenogenesis in insects
First to see human sperms with microscope
Anton van Leeuwenhoek and Louis Hamm
Studied structure of relatively advanced fetuses
Galen
Restrictions of Galen’s study
Prevented serious analysis of early embryonic development due to miniature dimensions of embryo
Founder of modern reproductive biology
Reignier de Graaf
Described ovarian follicles and fallopian tubes, studied ectopic pregnancy
Reigniet de Graaf
Lazzaro Spallanzani believed that
Male and female sex products are necessary to initiate development
What did Marcello Malphigi do?
Described accurately the development of chick in egg.
Developed modern comparative embryology
Karl Ernst von Baer
Germ Layer theory was proposed by:
Karl Ernst von Baer
State the Germ Layer Theory
There exists three germ layers from which organs are derived.
“Embryo development occurs through progressive remodeling and growth.”
Caspar Friedrich Wolff
Developed the cell theory
Matthias Schleiden, Theodor Schwann, and Rudolf Virchow
Implications of the Cell Theory
Embryology became a bona fide science, proved that development must occur via epigenesis
Theorized that development must follow a mosaic pattern
August Weismann
State the Germ Plasm Theory. Who proposed it?
Differentiated the somatic and germ cells, August Weismann
Function of somatic cells according to Germ Plasm Theory.
For the protection and proliferation of the germ plasm.
Function of germ cells according to Germ Plasm Theory.
For perpetuation of the species.
Other name for Mosaic Development
Weismann’s Theory of Nuclear Determination
Why is the Mosaic Model called as such?
Egg is considered a mosaic of discrete localized determinants.
Describe Mosaic development.
Nuclei contain factors that ate asymmetrically distributed in daughter cells, fate of each cell is predetermined.
What experiment did Roux perform?
Ablation Experiment or Embryonic Extirpation
Removed large pieces from eggs and discovered that any single monad was capable of forming any part of the completed embryo.
Hans Adolf Eduard Driesch
Consequence of Driesch’s experiment.
Led to the terms pluripotent and totipotent.
Describe regulative development.
Ability of the embryo to develop even if some cells are removed or rearranged.
Who performed the Induction and Transplantation experiments?
Hans Spemann and Hilde Mangold.
What is the organizer/evocator?
Dorsal lip of blastopore.
Distinguished between phenotype and genotype.
Wilhelm Johanssen
Describe the relationship between genotype and phenotype.
Genes are manifested through phenotype only upon the activation depending on time and space.
Worked on mutant genes and discovered genes encoded proteins.
Salome Glueksohn-Waelsch and Conrad Waddington
Unified science of embryology and genetics.
Developmental Genetics
Coined epigenetics.
Conrad Waddington
Epigenetics states that
The development of an embryo is due to a series of causal interactions between parts. It accounts for the development of an embryo and reminds one that genetic factors are the most important determinants of development.
