Development

Question 1

What are the three layers of the trophoblast?

Answer 1

Endoderm
Mesoderm
Ectoderm

Question 2

What is the difference between an embryo and fetus?

Answer 2

Embryo - organism in early stages of development that has not acquired anatomical form that is readily recognizable in appearance as a member of a specific species

Fetus - recognizable as a species. Marked by placentation development

Question 3

What trophoblastic layer do the gonads, and majority of the reproductive tracts develop from?>

Answer 3

Mesoderm

Question 4

The hypothalamus and anterior pituitary develop from what trophoblastic layer?

Answer 4

Ectoderm

Question 5

The vagina and vestibule or penis develops from what trophoblastic layer?

Answer 5

Ectoderm

Question 6

What provides nourishment for the early embryo?

Answer 6

Yolk sac

Question 7

What layer of the placenta is in contact with the mother?

Answer 7

Chorion

Question 8

In the placenta, the embryo is contained within the ________ cavity

Answer 8

Amniotic cavity

Question 9

T/F: organogenesis occurs outside the embryo

Answer 9

True

Brain and heart develop first

Body wall forms around them — > fetal membranes

Question 10

Where do gonadotropes originate?

Answer 10

Originate from yolk sac and migrate into embryo to genital ridge to form ovaries/testies

Question 11

What do you call the congenital disorder where there is exposure of abdominal visceral and spinal inversion because of a fissure in the ventral abdominal wall ?

Answer 11

Schistosomus reflexus

Question 12

What is the gestation length of a cow?

Answer 12

285days

Question 13

Gestation length of a dog?

Answer 13

62days

Question 14

Gestation length of a horse?

Answer 14

340days

Question 15

What reproductive events occur in the first trimester?

Answer 15

Migration of primordial germ cells from yolk sac

Sex cords develop in gonad, paramesonephric ducts

Sex evident from structures

Question 16

What reproductive structures develop int he second trimester?

Answer 16

Develop into male Or female structures

Formation of broad ligament

Question 17

What occurs in the 3rd trimester in males

Answer 17

Testicular descent

Question 18

What is sex differentiation vs sex determination?

Answer 18

Sex differentiation: the process whereby a group of unspecialized cells develop into a functional group of cells with a common function

Sex determination: a system that determines the sexual characteristics of an organism which generally consists of genetic or hormonal parameters

Question 19

What do you call the chromosomal complement of an organism?

Answer 19

Karyotype

Question 20

What is genotype vs phenotype?

Answer 20

Genotype= genetic alleles coding for a specific trait

Phenotype = observed traits (dependent on genotype)

Question 21

What is a chimera?

Answer 21

Single organism composed of genetically distinct cells. Fusion of two zygotes in a single embryo

Question 22

What is a mosaic?

Answer 22

An individual with two different cell lines that originated from the same individual ( one zygote )

Question 23

What is chromosomal sex, vs gonadal sex vs phenotypic sex?

Answer 23

Chromosomal - XX or XY (karyotype)

Gonadal sex = presence of testies/ovaries/ovotestis (determined by Sry gene on Y chromosome)

Phenotypic sex = determined by substances produced in testis to cause regression of female tract and formation of male tract

Question 24

What structure forms the male efferent ducts but will regress in the female?

Answer 24

Mesonephros

Question 25

What structure will form the epididymis and ductus deferens but will regress in the female?

Answer 25

Mesonephric ducts

Question 26

What structure will develop into the uterus and oviduct and cranial vagina in the female but will regress in the male

Answer 26

Paramesonephric ducts (Müllerian ducts)

Question 27

What do the primitive sex cords differentiate into in the male and the female?

Answer 27

Male - seminiferous tubules Female - regress, primitive follicular cells

Question 28

What are the key players in sex determination?

Answer 28

Testies determining factor (TDF) and SRY region on Y chromosome. —> testicular Development and testosterone production Dihydrotestosterone—> development of penis, scrotum, and accessory glands Anti-mullerian hormone — > degeneration of paramesonephric duct

Question 29

During fetal maturation, the testis descend into the scrotum.. is responsible for this?

Answer 29

Gubernaculum Attached at the inguinal ring to peritoneum Shortening/fattening pulls testis from their position caudal to the kidney into the scrotum