Developmental Biology Flashcards
Exam 1
When signals from one set of cells or a tissue direct the fate of a second set of cells or tissue.
Induction.
An example of this is the organizer which induces the anterior posterior axis of the embryo AND neural tissue.
Congenital defect associated with respiratory issues, reduced fertility, and situs inversus. Mutations in dynein leading to immotile cilia and flagella may be a cause.
Kartagener triad
The ability of a cell or tissue to respond to an inductive signal.
Competence.
Animal cap cells are competent to respond to the inductive signals from vegetal cells to form mesoderms.
Genes expressed from the maternal genome during oogenesis that affect development of the embryo.
Maternal Effect Gene
Vgl expressed in the vegetal hemisphere of amphibians
Cells of the drosophila egg chamber formed from mitosis of the oocyte stem cells that support and provide cytoplasmic component to the oocyte.
Nurse cells.
Proteins that bind to DNA and replace histones in the sperm for greater compaction of the sperm genetic material.
Protamines
Point during development when zygotic transcription begins. Occurs at 2-4 cell stage in mammals, 1000 cell stage in several aquatic models.
Mid-blastula transition
Multinucleated embryo of drosophila formed by mitosis of the genetic material and lack of cytokinesis with nuclei residing below the surface of the embryo.
Syncytial blastoderm
Hormone signaling begins at the ___________.
Pituitary gland in the hypothalamus.
Which part of the pituitary gland is responsible for hormone signaling; anterior or posterior?
Anterior.
The pituitary gland secrets gonadotropins. What are they and what does the name mean?
The name is a combination of “gonado” which refers to any reproductive tissue (testes, ovary, etc) and “tropins” which means they signal to the item preceding them.
Therefore the name means hormones that signal to the gonads.
What two hormones do gonadotropins stimulate?
Follicle stimulating hormone (FSH)
AND
Leutenizing hormone (LH)
Follicle stimulating hormones are named after their function in the _____ (male or female) system.
Female
Primordial oocytes in an ovary may turn into a primary follicle. During this process, they are frozen/arrested, and rescued by _________.
FSH (Follicle stimulating hormone)
After rescue of a primary follicle, it proceeds to become a secondary follicle. From this point on, what happens?
Estrogen is produced from the secondary follicle.
The secondary follicle becomes an egg surrounded by other cells and they subsequently release estrogen.
(Leutenizing Hormone) is released from the anterior pituitary and tells the egg to move to the fallopian tubes for ovulation and for the remaining ccells that were around the egg to leutenize (to become yellow) and produce progesterone.
In males, in the seminiferous tubules in the testi reside sustentacular cells or SERTOLI cells and outside the tubules reside interstitial cells or LEYDIG cells.
When FSH is released, what does it do?
It stimulates the Sertoli cells to produce ABP or Androgen Binding Protein.
What does leutenizing hormone (LH) do to Leydig cells?
It signals the Leydig cells outside of the seminiferous tubules to produce testosterone.
In males, FSH stimulates the Sertoli cells to produce ABP (Androgen Binding Protein) while LH (Leutenizing Hormone) will instead tell the Leydig cells to produce testosterone. If ABP is an androgen binding protein, and testosterone is an androgen, what is the expected result?
ABP and Testosterone bind, inducing the production of sperm.
In females, FSH = Primary follicle -> Secondary Follicle -> Estrogen
In males FSH = Sertoli cells -> ABP
In females LH = Ovulation -> corpus luteum -> Progesterone
In males LH = Leydig cells -> Testosterone
What is the conclusion for female systems and male systems?
The female reproductive tissue exposed to FSH and LH prepared uterus and prepared for ovulation.
The male reproductive tissues exposed to FSH and LH prepared testis for sperm production.
In males and females, testosterone leads to negative feedback inhibition.
XX gonadal cells activate the ____ pathway.
Wnt
XX gonadal cells activating the Wnt pathway produce the transcriptional regulator ______, which inhibits the development of gonadal cells into testis cell types and activates the genes to promote the development of follicle cells of the ovary instead.
B-catenin.
XY gonadal cells activate the gene encoding the Sry transcription factor. Which may activate ______, which inhibits the development of gonadal cells into ovary cell types and activates the genes to promote the development of testes and subsequent Sertoli cells and Leydig cells.
Sox9
The differentiation of the germ cells into gametes: eggs and sperm
Gametogenesis
The bipotential precursors of
both eggs and sperm; if they reside in the ovaries they become eggs, and if they reside in the testes they become
sperm
primordial germ cells (PGCs)
The cells that generate the sperm or eggs do not originally form inside the gonads. In Drosophila and mammals, they form in the posterior portion of the embryo and migrate into the gonads.
True/False
True
Vasa and Nanos are critical genes used to ____________.
Determine germ cell specification and development. Blocking the development of Vasa/Nanos inhibits the development of germ cells.
I.e; No Vasa and Nanos, no germ cells
Generation of a mature egg “ovum”
Oogenesis
Specification of the primordial germ cells involves these two crucial proteins;
Vasa proteins
Nanos proteins
_____ proteins maintain germ cell identity (keep them germ cells)
Vasa proteins, supporters of identity
_____ proteins act as repressors of cell death pathways (affording cell differentiation)
Nanos proteins, repressors of death
