PSB4731 Quiz 3Elaine HullL&B 6: Sexual Development Review1. What is capacitation in sperm? What is the acrosome reaction? Why is it important?- Capacitation: Enzymes in the uterus/oviduct eat away the masking proteins to reveal receptors for the zona pellucida, in which the sperm can then smell the oocyte and swim faster, yet they can live only a few hours after.- Arosome Reaction: Receptors exposed by capacitation bind to zona pellucida and release enzymes that eat through it until it reaches the ovum. 2. What happens to the zona pellucida after a sperm penetrates the oocyte?- Once it binds to the ovum it then releases Ca++ and then the enzymes cause the zona pellucida to become impenetrable by any more sperm.3. How long does it take the pronucleus in the oocyte to form after penetration by a sperm? - 4-6 hours4. What do the sperm and oocyte pronuclei do as soon as the oocyte pronucleus forms?- One set of chromatids from the secondary oocyte becomes the female pronucleus.- The sperm head becomes the male pronucleus.- The chromosomes in the 2 pronuclei don’t fuse yet undergo replication followed by mitosiscell division.- Finally, in the new 2-cell conceptus each cell is diploid, possessing both maternal and paternal versions of homologous chromosomes.5. What is a blastocyst, and what does it do?- Blastocyst: 32-cell stage conceptus that develops into a fluid-filled cavity which then hatches itself from the zona pellucida and implants in the wall of the uterus about 6 days after conception.o Implantation requires both E and P from corpus luteum, thus blastocyst secretes hCG to rescue the corpus luteum from its normal regression at the end of the luteal phase.o The inner cell mass becomes the embryo and the outer layer of cells forms part of the placenta.6. By what age does the fetus begin to kick, suck its thumb, drink amniotic fluid, urinate, wake & sleep? - 14-16 weeks7. What is the main source of P after ~14 – 16 weeks post-conception?- Fetal side of placenta secretes P; fetal adrenal produces androgens, which are then aromatized to E by placenta.8. What is the DAX 1 gene? - DAX-1: located on the X chromosome and directs development of ovaries on outer (cortex)part of gonad.9. What is gonadal intersexuality (true hermaphroditism)? What are 2 ways it can be produced?1PSB4731 Quiz 3Elaine Hull- Gonadal Intersexuality (Hermaphroditism): possess both ovarian and testicular tissue within gonads in which most individuals become infertile yet several have become pregnant and delivered children.o Can occur by early fusion of brother and sister embryos into one (xxy) or X-inactivation in female genotype (xx) with translocation of SRY on one X.o Can occur by 2 sperm (1X & 1Y) fertilizing an ovum and 1 of its polar bodies.10. What is X inactivation, and why is it important?- X-inactivation: each cell in female embryo (xx) randomly selects either the maternal or paternal X chromosome for inactivation in which the descendants of those cells retain the same pattern of inactivation throughout the rest of development. o Without X-inactivation, females would produce twice as many of the proteins as males. 11. What is the origin and destination of migrating germ cells that will become sperm or oocytes?- Germ cells that become oocytes or sperm originate from the yolk sac and migrate to their destination at the genital ridge.12. What are Müllerian ducts? What do they need to develop?- Mullerian Ducts: need the absence of AMH in order to develop into the oviducts, uterus, and the deeper part of the vagina.13. What are Wolffian ducts? What do they need to develop?- Wolffian Ducts: need T to develop into the epididymis, vas deferens, ejaculatory ducts, and seminal vesicles; AMH is also needed in order to cause the Mullerian Ducts to disappear. o SRY on Y chromosome causes development of testes in order to first produce T and AMH.14. What is Turner syndrome? What are some symptoms?- Turner Syndrome: (XO) phenotypic females who don’t enter puberty and are infertile dueto ovaries not fully developed to produce the necessary steroid hormones for puberty; must be treated with hormones to induce puberty; poor visuospatial skills; short stature; broad chest; webbed necks.o Ovaries need both XX chromosomes to fully mature.15. What is Klinefelter syndrome? What are some symptoms?- Klinefelter Syndrome: (XXY/XXXY) phenotypic males who are generally tall with somewhat feminized secondary characteristics and low T levels; small testes; breast development; sparse facial hair; infertile; poor language skills. o Infertile due to having 2 DAX-1 genes causing ovary development.16. How can syndromes like XO, XXY, or XYY occur?- Chromosomal anomalies can occur when there are fewer or more than two sex chromosomes as a result of nondisjunction during the Anaphase of mitosis. 2PSB4731 Quiz 3Elaine Hull17. Describe androgen insensitivity syndrome: its cause and symptoms.- Androgen Insensitivity Syndrome: XY genotype male with normal testes, AMH and T development due to SRY gene with deterioration of Mullerian Ducts, yet insensitive to T from mutation of gene for androgen receptor causing failure in development of Wolffian Ducts and leading to phenotype female; infertile; worse than other males at spatial tasks. 18. Describe congenital adrenal hyperplasia (CAH): its cause and symptoms in males and females.- Congenital Adrenal Hyperplasia (CAH): defect in enzyme that produces cortisol thus leading to low cortisol levels that causes negative feedback leading to high ACTH from anterior pituitary, which “tries” to get adrenal glands to produce more cortisol; adrenals increase what they can produce which is androgens and other steroids, thus causing masculinization of external genitilia and the brain in males and females. o In males differentiation is OK but early puberty and cessation of growth occur.o In females the clitoris is enlarged and the labia is fused; play more with boys’ toys, less interested in motherhood, more inclined to male-typical activities and careers, more likely to be attracted to women but more hetero- than lesbian, excel in visuospatial tasks. 19. Describe 5-alpha reductase deficiency: its cause and symptoms.- 5-alpha reductase deficiency: normal internal genitilia development with testes producingT and AMH causing Mullerian ducts to degenerate, yet lack of DHT leads to inadequate masculinization of external genitilia at birth (ambiguous or female characteristics) since DHT is