Exam 2: Lecture 20: Development of the Female and Male Systems

Question 1

What is an embryo?

Answer 1

-Organism in early stages of development
-Generally has not acquired an anatomical form readily recognizable in appearance as a member of a specific species
-Placentation has not yet taken place

Question 2

What is a fetus?

Answer 2

-Potential offspring within the uterus that is generally recognizable as a member of a given species on U/S
-Marked by development of placenta

Question 3

What is embryology?

Answer 3

-Primary embryonic germ layers

Question 4

The embryo starts as what that eventually turns into what?

Answer 4

-Starts as mass of cells that eventually form cell layers & will differentiate into embryo proper & placenta

Question 5

What does the endoderm become?

Answer 5

-Digestive system
-Lungs
-Endocrine system

Question 6

What does the mesoderm become?

Answer 6

-Muscle
-Skeleton
-Cardiovascular
-Reproductive system

Question 7

What does the ectoderm become?

Answer 7

-Nervous system
-Skin
-Hair

Question 8

What eventually makes the yok sac in embryology and placentation?

Answer 8

Blastocel

Question 9

What is the posterior lobe of the pituitary gland, what does it contain, and what is the other name?

Answer 9

-Neural tissue
-Contains axons & nerve terminals of neurons from hypothalamus
-Neurohypophysis

Question 10

What is the anterior lobe of the pituitary gland, where is it from, and what is the other name?

Answer 10

-Stomodeal ectoderm (tissue from roof of mouth, glandular epithelial cells produce glycoprotein hormones)
-Adenohypophysis

Question 11

The posterior lobe of the pituitary is formed from

Answer 11

-A diverticulum from the floor of the brain called infundibulum

Question 12

The anterior lobe of the pituitary is formed from

Answer 12

-An evagination from the oral cavity called Rathke’s Pouch

Question 13

The pituitary gland lives in a bony prominence called the

Answer 13

-Sella turcica

Question 14

What are the major hormones produced by the posterior pituitary?

Answer 14

-Growth hormone
-Prolactin

Question 15

What are the major hormones produced by the anterior pituitary?

Answer 15

-ACTH
-TSH
-FSH
-LH

Question 16

What are 3 things produced by the posterior pituitary and where are they?

Answer 16

-ADH -> kidney tubules
-Oxytocin -> smooth m. in uterus, mammary glands

Question 17

What 5 things are produced by the anterior pituitary and where are they?

Answer 17

-Gonadotropins -> ovaries & testes
-Growth Hormone -> bones, tissues
-Prolactin -> mammary glands
-ACTH -> adrenal cortex
-TSH -> thyroid gland

Question 18

How are hormones released in the posterior pituitary?

Answer 18

-Neurohormones are deposited directly into circulation

Question 19

How are hormones released in the anterior pituitary?

Answer 19

-Utilizing hypothalao-hypophyseal portal system

Question 20

Sexual differentiation involves

Answer 20

Specific substances

Question 21

What is the definition of “sex differentiation”?

Answer 21

-Process where a group of unspecified cells develops into a functional, recognizable group of cells
-Ex: male & female reproductive tracts

Question 22

What is the definition of “sex determination”?

Answer 22

-System that determines the sexual characteristics of an organism which generally consists of genetic or hormonal parameters

Question 23

What is the definition of “karyotype”?

Answer 23

-Describes chromosomal complement of an organism

Question 24

What is a genotype?

Answer 24

-Describes alleles genetic constitution of an individual (deals with/ genes or alleles that code for specific traits)
-Mendel’s Square

Question 25

What is a phenotype?

Answer 25

-Describes observed characteristics (ex: penis, vulva, testicles)

Question 26

What is a chimera?

Answer 26

-Produced by fusion of 2 different zygotes in a single embryo

Question 27

What is a mosaic?

Answer 27

-Individual w/ 2 different cell lines that originated from same individual

Question 28

What is this an example of?

Answer 28

-Chimera -Cells contain 2 types of DNA (2 embryos fused together)

Question 29

Most male tortiseshell cats are

Answer 29

-Chimeras

Question 30

This is an example of

Answer 30

-Mosaic -Individual has 2 or more genetically different sets of cells in their body

Question 31

Downs syndrome is a example of

Answer 31

-Mosaic

Question 32

Sexual differentiation relies on 3 stages, what are they?

Answer 32

1. Chromosomal sex (karyotype) 2. Gonadal Sex 3. Phenotypic sex **each stage is dependent on the previous stage**

Question 33

How is chromosomal sex determined?

Answer 33

-At fertilization

Question 34

How is gonadal sex determined?

Answer 34

-By the "sex determining region of the Y chromosome" (SRYgene) -Srygene induces testes formation

Question 35

How is phenotypic sex determined?

Answer 35

-By substances produced in the male testes to cause regression of female tract & formation of male tract

Question 36

The karyotype of the organism involves the number of chromosomes followed by ____, which only tells the observer what?

Answer 36

-XX for female -XY for male -Only tells if chromosomally female or male

Question 37

The embryo starts in a sexually ____ stage

Answer 37

indifferent

Question 38

The cloaca will become

Answer 38

the anus

Question 39

____ migrate from yok sac up into the gonadal ridge & will differentiate from there

Answer 39

Primordial germ cells

Question 40

Pronephros become

Answer 40

-Primitive kidney (1st of 3)

Question 41

Mesonephros become

Answer 41

-Intermediate kidney (2nd of 3) -Male: form efferent ducts -Female: regress

Question 42

Metanephros become

Answer 42

-Final functional kidney (3rd of 3) -Functional kidney

Question 43

Mesonephric ducts (wolffish ducts) become

Answer 43

-Male: epididymis & ductus deferens -Female: regress

Question 44

Paramesonephric ducts (Mullerian ducts) become

Answer 44

-(Located beside mesonephric ducts) -Male: regress -Female: Uterus & oviducts & cranial vagina

Question 45

Primitive sex cords become

Answer 45

-Male: seminiferous tubules -Female: regress, primitive follicular cells

Question 46

Primitive germ cells become

Answer 46

-Male: spermatogonia -Female: oocytes

Question 47

Determination of physical sex organ characteristics relies on the presence of

Answer 47

-Initially, hormone Testis Determining Factor (TDF) & "sex-determining region Y" (SRY) -Then, Anti-Mullerian Hormone (AMH) causes degeneration of paramesonephric duct -Last, Dihydrotestosterone (DHT) causes development of penis, scrotum, & accessory sex glands

Question 48

What happens with a female XX chromosomal pair?

Answer 48

No SRY protein -> ovaries develop -> no AMH -> paramesonephric ducts become oviducts, uterus, cervix & part of vagina -> complete female tract

Question 49

What are the steps in the developmental sequence of the testis?

Answer 49

1. Undifferentiated sex cords align themselves 2. Rete tubules & mesonephric tubules now interconnected & become seminiferous tubules 3. Mesonephric duct transformed into epididymis & ductus deferens

Question 50

AMH (anti-mullerian hormone) is produced by

Answer 50

Sertoli cells

Question 51

Presence of testosterone causes

Answer 51

regression of the female duct system

Question 52

How do the testes descend?

Answer 52

-Prior to descent, testes in retroperitoneal position -Gubernaculum connects fetal testis to peritoneum -After gubernaculum goes through inguinal ring, there is rapid growth of distal gubernaculum -Testes pulled through inguinal canal by gubernaculum shrinking & abdominal pressure from visceral growth provides extra push for testes -Continually shrinking gubernaculum keeps pulling testis into scrotum & testis now surrounded by double layer of peritoneum in scortum

Question 53

The remnants of the gubernaculum become

Answer 53

-Proper ligament of the testis & the ligament of the tail of the epididymis

Question 54

Male differentiation begins with

Answer 54

Sexually indifferent stage

Question 55

What happens in the presence of AMH in male differentiation?

Answer 55

-Paramesonephric/Mullarian ducts regress -Gonads increase in size (cause Mullarian ducts to disappear) -Kidneys (metanephros) grow & move cranial

Question 56

The remnant mesonephros are the

Answer 56

future efferent ducts

Question 57

In female differentiation, the absence of testosterone, AMH & DHT causes

Answer 57

-Coelomic epithelium to become the ovarian cortex -Rete tubules have disappeared -Paramesonephric (Mullarian) duct develops & enlarges -Mesonephric ducts regress completely -Follicles begin to develop

Question 58

In female differentiation, what forms the cervix & uterine body?

Answer 58

-Paramesonephric/Mullarian ducts fusing

Question 59

In female differentiation, the caudal vagina originates from

Answer 59

-The urogenital sinus that invaginates from the exterior skin, so is stratified squamous epithelium

Question 60

What forms the cranial vagina?

Answer 60

-The paramesonephric ducts completely fuse more caudally & form the body of the uterus, the cervix, or the cranial vagina

Question 61

What forms the broad ligament that supports the reproductive tract in the abdominal cavity

Answer 61

-The connective tissue layer from the peritoneum

Question 62

In external differentiation, the cloacal folds turn into

Answer 62

A scrotum & penis or labia

Question 63

What happens to the cloacal folds when there is DHT?

Answer 63

-Genital swelling -> scrotum & urethral groove

Question 64

What happens to the cloacal folds when there is no DHT?

Answer 64

-No genital swelling -> major & minor labia of vulva, vulvar cleft, clitoris

Question 65

The fetal stage consists of

Answer 65

Rapid fetal growth & maturation of the organs that were produced during embryonic stage

Question 66

What happens in fetal maturation in the male?

Answer 66

-Testicles descend into scrotum

Question 67

What happens in fetal maturation in the female?

Answer 67

-Broad ligament develops -Ovaries migrate caudally due to fetal growth