Book Questions Flashcards
During spermatogenesis histone is replaced by what to allow for better packing of condensed chromatin ?
Proamine
What cell type is located outside the blood testis barrier?
Primary spermatocyte
Which of the following cells normally participates in mitotic divisions?
a. primary oocyte
b. oogonium
c. primary spermatocyte
d. spermatid
e. secondary spermatocyte
oogonium
In a chest x ray the radiologist sees what looks like teeth, what is the probably embryological explination?
Primordial germ cells did not migrate correctly leading to a mediastinal teratoma.
When does meiosis begin in the female and in the male?
In females meiosis begins during embryonic life and in males it begins at puberty.
What stage in meiosis is oogenesis arrested in ?
Diplotene stage shortly after birth up until puberty. After puberty at the beginning of each cycle some will resume meiosis until metaphase II.
What is the underlying cause of spontaneous abortions in early weeks of pergnancy?
Chromosome abnormalities
What is the difference between spermatogenesis and spermiogenesis?
Spermatogenesis is the entire process of sperm formation from a spermatogonium, including two meiotic divisions and spermiogenesis. Spermiogenesis is the process of transformation from a postmeiotic spermatid to a highly specialized spermatozoon.
The actions of what hormones are responsible for the changes in the endometrium during menstrual cycle?
Estrogen secreted by the ovary support proliferative phase. Progesterone is secreted by CL and responsible for secretory phase which prepares for implantation.
Sertoli cells in the testis are stimulated by what two major reproductive hormones?
FSH from AP and testosterone secreted by the Leydig cells of the testis
Of the barriers to sperm survival and transport within the female tract, low pH is most important in what structure?
Vagina
The principal energy source for ejaculate spermatozoa is?
Fructose in the seminal vesicle fluid
What is the principal hormone stimulus for ovulation?
Surge in LH
What is capacitation?
Step required for sperm to undergo acrosomal reaction, it requires the binding of sperm to tubal epithelium and removes cholesterol from sperm
Name two functions of ZP3 protein of the Zona Pellucida?
- stimulates acrosomal reaction through G proteins
2. Exchanges sodium and hydrogen ions to increase pH
What is polyspermy and how is it prevented after spermatozoon enters?
Polyspermy is when multiple sperm fertilize the egg. It is blocked by fast electrical block and then slow block or zona reaction that releases granules to inactivate sperm receptors in the ZP.
A woman gives birth to septuplets, what is the likely reason for multiple births?
She most likely took clomiphene to stimulate ovulation. Natural septuplets arent seen often.
When multiple oocytes obtained by laparoscopy are fertilized in vitro why are up to three embryos implanted and why are others frozen?
Multiple embryos are implanted to enhance the chances of the embryo surviving until birth. The remaining are frozen in case pregnancy does not result the first time it can be re done.
What are some functions of the zona pellucida?
Promotes maturation of the oocyte and follicle.
Serves as barrier that allows sperm of same species in.
Modified ZP prevents additional sperm entry after fertilization
Serves as immunological barrier between mom and baby
Prevents premature implantation of cleaving embryo into the wall of uterine tubes.
What is the most common condition associated with spontaneously aborted embryos?
Chromosomal abnormalities
What tissue from the implanting embryo directly interfaces with endometrial CT?
Syncytiotrophoblast
Identical twinning is made possible by what process of early embryo?
Regulation
What is the importance of the inner cell mass of the cleaving embryo?
The embryonic body proper arises from ICM
Parental imprinting is a phenomenon that shows certain homologous maternal and paternal chromosomes have different influences on development. Excess paternal influences result in abnormal dev. of what type of tissue at the expense of dev. of the embryo?
Trophoblastic tissues
What is the functions of integrins in implantation?
They allow the trophoblast of the embryo to adhere to uterine epithelium
What is the cellular origin of syncytiotrophoblast of the implanting embryo?
Cells are derived from the cytotrophoblast and fuse to form this.
What is a homeobox?
a highly conserved sequence of 180 nucleotides that codes for 60 aa found i n homeodomain TF proteins.
Which of the following is a TF?
a. FGF
b. Pax
c. TGF
d. Notch
e. Wnt
Pax
Works with Sox to affect the lens
Where in the cell is RA receptor located?
Nucleus
A mutation of what receptor is basal for carcinomas of the skin?
Patched
Zinc fingers or helix loop helix arrangements are members of what class of molecules?
Transcription factors
Sonic hedgehog is produced in which signaling center?
The notochord, intestinal portals, floor plate of neural tube, zone of polarizing activity in the limb bud