Development of Female and Male Systems

Question 1

Define an embryo.

Answer 1

Has not yet acquired an anatomical form that is readily recognizable.

Question 2

Define a fetus.

Answer 2

Presence of all major body organs. Recognizable as a member of a given species.

Question 3

What are the 3 general steps in embryology?

Answer 3

Cell mass
Cell layers start flat
Organogenesis “outside” the embryo

Question 4

What 3 cell lines are in the cell mass?

Answer 4

Endoderm
Mesoderm
Ectoderm

Question 5

What cell lines give rise to the reproductive organs?

Answer 5

Ectoderm and mesoderm

Question 6

What is schistosomus reflexus?

Answer 6

The organs never go into the body cavity, but the fetus develops to term. Spine is also bent the wrong direction. All this results in often severe dystocia.

Question 7

T/F: The embryonic period is relatively similar in all species.

Answer 7

True. It is gestational length that differs.

Question 8

During what trimester can you sex the fetus?

Answer 8

During the first trimester.

Question 9

What is sex differentiation?

Answer 9

Process where a group of cells develops into a functional, recognizable group of cells.

Question 10

What is sex determination?

Answer 10

Determines the sexual characteristics of an organism.

Question 11

What is a karyotype?

Answer 11

The number and appearance of chromosomes.

Question 12

What is a genotype?

Answer 12

Describes the alleles.

Question 13

What is a phenotype?

Answer 13

Describes the observed characteristics. The expression of the genotype.

Question 14

What is a chimera?

Answer 14

An organism with cells from two different zygotes.

Question 15

What is a mosaic?

Answer 15

Two or more populations of cells with different genotypes in one individual that developed from a since fertilized egg.

Question 16

What are the 3 stages of sexual differentiation?

Answer 16

Chromosomal sex/karyotype (XX or XY)
Gonadal sex
Phenotypic sex

Question 17

What does the chromosomal sex tell you?

Answer 17

Just that the animal is chromosomally male or female

Question 18

After what percent of gestation is the sex usually obvious?

Answer 18

After 15%

Question 19

What does the reproductive tract develop close to and at the same time as?

Answer 19

The renal system.

Question 20

What is the pronephros?

Answer 20

Primitive kidney, nonfunctional.

Question 21

What is the mesonephros?

Answer 21

Intermediate kidney

Question 22

What is the metanephros?

Answer 22

Final, functional kidney.

Question 23

In the female and male, what happens to the mesonephric ducts (Wolffiean ducts)?

Answer 23

They regress in the female, and become the epididymus and ductus deferens in the male.

Question 24

In the female and male, what happens to the paramesonephric ducts (Mullerian ducts)?

Answer 24

In the female, they become the uterus, oviducts and cranial vagina. In the male, they regress.

Question 25

What happens to the primitive sex cords?

Answer 25

They regress in the female, and become the seminiferous tubules in the male.

Question 26

What are the female primitive germ cells called?

Answer 26

Oocytes

Question 27

What are the male primitive germ cells called?

Answer 27

Spermatogonia

Question 28

What is the testis determining factor?

Answer 28

A sex determining region on the Y chromosome that stimulates the development of the male reproductive tract when present, or the development of the female reproductive tract if absent.

Question 29

What is anti-mullerian hormone?

Answer 29

Stimulates differentiation of Leydig cells and degeneration of paramesonephric ducts.

Question 30

What does dihydrotestosterone promote?

Answer 30

The development of a penis, scrotum and accessory sex glands.

Question 31

Where in the body are the testis formed?

Answer 31

Near the ribs!

Question 32

What structure do the oviducts, uterus and cranial vagina develop from and what cell type are they?

Answer 32

From the paramesonephric ducts | Mesoderm

Question 33

T/F: The female gonads and ducts do not originate retroperitonaly.

Answer 33

False. They DO originate in the retroperitoneal space.

Question 34

What occurs during fetal maturation?

Answer 34

The organs that were produced during the embryonic stage mature. Male: Testicles descend into scrotum Female: Broad ligament develops and ovaries migrate caudally.

Question 35

During what trimester does testicular descent occur?

Answer 35

In the 2nd trimester for bulls and rams In the 3rd trimester for boars and humans In and beyond the 3rd trimester in colts

Question 36

What structure helps pull the testis into the scrotum?

Answer 36

The gubernaculum

Question 37

What are the 3 phases in testicular descent?

Answer 37

Growth and elongation of body away from testes Rapid growth of extraabdominal gubernaculum Shrinkage of the gubernaculum within the scrotum

Question 38

What are 2 common testicular descent failures?

Answer 38

Cryptorchidism | Inguinal hernia