Lecture 69: Development of Female and Male Systems

Question 1

Define an embryo

Answer 1

• An organism in the early stages of development
• It generally has not acquired an anatomical form that is readily recognizable as a member of specific species
• Placentation has not taken place yet

Question 2

Define a fetus

Answer 2

• Potential offspring within the uterus that is generally recognizable as a member of a given species
• Marked by the development of placentation

Question 3

What are the three embryonic gem layers? Name them and state what systems develop from each layer.

Answer 3

• Endoderm: digestive system, lungs, endocrine system
• Mesoderm: muscle, skeleton, cardiovascular, repro system
• Ectoderm: nervous system, skin, hair

Question 4

The posterior lobe of the pituitary gland is formed by what?

Answer 4

Formed from a diverticulum from floor of brain (infundibulum)

Question 5

The anterior lobe of the pituitary gland is formed by what?

Answer 5

Formed from an envagination from the oral cavity (Rathke’s Pouch)

Question 6

Define sexual differentiation.

Answer 6

The process whereby a group of unspecified cells develops into a functional, recognizable group of cells that have a common function (female and male repro tracts)

Question 7

Define sex determination.

Answer 7

A system that determines the sexual characteristics of an organism which generally consists of genetic or hormonal parameters

Question 8

Define karyotype.

Answer 8

Describes the chromosomal complement of an organism

Question 9

Define chimera.

Answer 9

Produced by the fusion of two different zygotes in a single embryo

Question 10

Define mosaic.

Answer 10

an individual with two different cell lines that originated from the same individual (from a non-dysjunction event)

Question 11

Sexual differentiation relies on 3 stages, with each stage being dependent on the previous one. What are they?

Answer 11

1) Chromosomal Sex (Karyotype)
2) Gonadal Sex
3) Phenotypic sex

Question 12

The karyotype of the organism involves what?

Answer 12

The number of chromosomes followed by:
- XX for female
- XY for male

This only tells the observer if it is chromosomally female or male

Question 13

Primordial germ cells originate in the _____ ______.

Answer 13

Yolk sac

Question 14

Describe the “key players” of sex determination in the male

Answer 14

• Initially the hormone Testis determining Factor (TDF) and Sex-determining region y (SRY) on the Y chromosome causes the development of the testes (produces testosterone)
• Then Anti-Mullerian Hormone (AMH) causes degeneration of the paramesophric duct
• Then Dihydrotestosterone causes development of the penis, scrotum, and accessory sex glands

Question 15

Describe the process of male sexual differentiation.

Answer 15

1) Embryo has XY chromosomal pair
2) SRY protein is present, which causes the development of the testis
3) Sertoli cells secrete anti-mullerian hormones (AMH) and enzymes to produce dihydrotestosterone
4) DHH gene causes differentiation of fetal leydig cells which produce testosterone and cause the development of the male duct system
5) AMH and testosterone degenerate paramesonephric duct, which produces dihydrotestosterone, and causes development of penis, scrotum, and accessory sex glands

Question 16

Describe the process of female sexual differentiation

Answer 16

1) Embryo has XX chromosomal pair
2) No SRY protein, causes ovaries to develop
3) No AMH
4) Paramesonephric ducts become the oviducts, uterus, cervix and part of the vagina