Sex Development and Determination

Sex Development and Determination

Q1 Embryos at 6 weeks
Describe the precursor reproductive structures in embryos at 6 weeks. Focus your response on explaining:
(1) the bipotential nature of the gonad precursor structures. What does it mean for the gonads to be bipotential?
(2) Name the precursor structure to the male reproductive tract and the precursor structure to the female reproductive tract.
(3) Answer the following: Do embryos at 6 weeks have both precursor structures named above?
For your response to any part of this question, there is no need to provide details on physiology, hormones, chromosomes, etc. Just answer or address what is being asked in the question.

Q2 Path to the development of reproductive structures
Two paths of sex determination and development were described in the “Sex Determination and Development” lecture. One path directs the formation of female reproductive structures, another directs the formation of male reproductive structures.
For the following problems, only consider the scenarios where the “normal” path of development occur; in other words there are no abnormalities in hormone levels, receptor function, chromosome number.
Q2.1 Development of male reproductive structures.
(1)Explain what pair of chromosomes directs the development of male reproductive structures.
(2) What is the name of the gene that is responsible for this?
(3) What reproductive structure will form when this gene is turned on?
(4) Which two hormones will be secreted from the gonads?
(5) Describe what happens to the ducts as a result of this hormone production?
Q2.2 Development of female reproductive structures
Address the following:
(1) Explain what pair of chromosomes will result in the development of female reproductive structures.
(2) What is different about this pair of chromosomes with respect to the male sex chromosomes? (hint does it have or not have “the gene”?)
(3) Explain why development of the female reproductive structures is referred to as the “default pathway” for development.
(4) Which type of gonads form? Do these gonads secrete the same two hormones that are secreted by the male gonads? Explain what impact this will have on development of the precursor reproductive structures
a. Describe what happens to the ducts and describe the role that hormones (or lack of hormones) have on the destiny of the ducts.

Q3 Intersex Individuals
(1) Explain in a few sentences and in your own words how binary classification excludes intersex individuals.
(2) From the following options, select all the possible reasons that might lead to a person being intersex.
A. A person with extra or missing chromosomes
B. Abnormal levels of hormones during embryonic development
C. Defective or absent hormone receptors