Exam 3Fundamentals of Human ReproductionChapter 1: Reproductive System AnatomySexual Differentiation- Prenatal (in utero) development of the male and female reproductive structureso MALE DIFFERENTIATION : Y Chromosome induces the indifferent gonads (neither male nor female initially) to become testes. This begins approximately during 6th -7th week of gestation Testes produce 2 types of hormones: - Androgens (male hormones), testosterone locally, will act on the Wolffian duct system to induce internal male (seminal vesicles, vas deferens and epididymis) reproductive structures and on the external genitalia to induce male external structures.- Mullerian duct inhibiting hormone (MDIH) will act on the mullerian duct system to cause them to degenerate. - Dihydrotestosterone (DHT) (potent androgen) causes the external genitalia to become male structures (scrotum, penis, prostate gland). The receptors only respond to testosterone and the cell changes the systemic testosterone in the blood, toDHT.o FEMAL DIFFERENTIATION : no Y chromosome, Androgens are absent and the Mullerian ducts will become the internal female reproductive structures (oviducts, uterus, upper portion of vagina). Androgens are absent, so the female external structures will develop (clitoris, labia, vagina).- Genetic Sexo Established at fertilization: XX=female, XY=male Internal Male Structures- Ejaculatory Ducts: lead to the urethra and junction of ducts of seminal vesicles and vas deferens- Prostate Gland- Cowpers GlandHomologous Structures - It is clear that male and females are anatomically different, but the reproductive strictures develop from the exact same tissues.- If androgens are present the tissues become male structures and without androgens they become female structures - The structures are termed homologous structures. Male FemaleScrotum (labia folded over) Labia MajoraPenis ClitorisCowpers Gland: pre-ejaculatory fluid Bartholins’s gland: lubricant during sexualexcitationTestes OvariesCritical Role of the Y Chromosome:- We see that the y chromosome is necessary for the creation of the male reproductive structures- Without a Y the default development will be female - The androgens (male hormones) from the developing testes are critical Adrenogenital Syndrome AGS - Can affect both genders, roughly 1 in every 10,000 to 18,000 children are born with this condition- The syndrome will cause - Males: excessive male hormones will cause quite a few things to occuro Go into puberty at an early age- Females: genitalia could look both male and female. - Treated by feminizing the genitalia**SIDE NOTE** Hormones and Sexual Differentiation of the Brain - Males and females carry books differently. - Maybe because body posture and the way the limbs are held (hip width, hip shelf and arm length). - Most men have ring fingers that are longer than their index fingers but most women have longer index fingers than ring fingers. o Digit ratio has been assumed to be related to the exposure of testosterone.ICLICKER: 1. If we prevented testosterone from being changed to DHT (dihydrotesterone) we would NOT find:A) epididymisB) vas deferensC) penisAnswer: C2. The scrotum is homologous to the A) Labia minora (minor lips)B) Cowper's glandC) Bartholin's glandsD) ClitorisE) Labia majora (major lips)Answer: E3. If the theory about prenatal androgen exposure and digit length is true then we would expect to find in a person (male or female) with AGS:A) Ring finger longer than index fingerB) Index finger longer than ring fingerAnswer: A4. An individual with a genotype of XXY would have:A) OvariesB) TestesC) Neither ovaries or testesAnswer: BLecture 2Sexual differentiation- XY : any time there is a Y, testes will occur.o H-Y antigen will cause differentiation of testes o Testosterone will differentiate wollfian ducts into internal genitalia DIH will cause the external genitilia o MIH will inhibit mullerian ducts - XX : any time there isn’t a Y an internal vagina will developo Mullerian ducts will create the internal vagina structures o Absence of androgens will causes external female genitalia to developAdrenogenital Syndrome (genetic disorder) from lecture 1 - Androgen’s coming from the a child’s adrenal cortex and cause male external structures to develop- Genetic sex is one thing but hormonal sex is another! - This syndrome illustrates the effects of male hormones (androgens) on the development of a child. - For Boys (with XY chromosomes) the excessive male hormones will cause quite a few things to occur o He might go into puberty at an early age, have a deeper voice, small testes, an enlarged penis and a strong muscular systemo He must be treated with steroids- For girls (XX) the excessive male hormones will cause external genitalia to look like boy and girl because the externalgenitalia develop at 12 weeks onthe outside and androgen batheschild on the outside. o Inside she is completelyfemale o She would most likelyundergo surgery toreconstruct her externalgenitalia, feminizationsurgery. o Deficiency of hormonescoritsol and aldosterone,need to be treated with cortisone. Just called hormone therapy. Summary: o Female with AGS will have: ovaries, oviduct, uterus, vagina, be fertile, and some masculinization of external genitalia.Androgen insensitivity Syndrome (AIS) o All individuals have the genotype XYo 2-5/100,000 have this syndrome, not always complete (people could have mild form)o Receptors are key to this syndrome, the cells of the body will not respond to androgen from the abdominal testes. o Wolffian ducts are insensitive to male hormones (androgen) so no male internal structures will develop, and testes will remain in the abdomen. o The Mullerian ducts, however, have regressed because the body does respond toMIH. o They are female phenotypes but male genotypes External structures of the male o Penis o Erectile tissue: erection is a vascular phenomenom. Blood flows into the tissues (gets trapped in the connective tissue) and causes an erection. Corpora cevernosa penis: the spongy tissue that gets blood duringan erection Corpusspongiosumpenis: morespongy tissuethat getsblood duringan erection -Urethra:alsohousedin acorpus spongiosum. o Scrotumo Function: to keep the testes about 5 degrees cooler. ICLICKER1. With the AGS (XX) would we find:A) OvariesB) TestesC) Neither ovaries or testesAnswer: A2. Will Mullerian ducts become internal female reproductive structures in an XXAGS
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