Lecture 3 - Testicular Function Flashcards
At how many weeks gestation do the male and female sex organs begin to appear different?
7 weeks
Which gene determines whether male or female sex organs develop?
The SRY gene (sex-determining region Y gene), this is the testis determining factor.
What are examples of when the SRY gene has malfunctioned?
Apparent females who have XY chromosomes and the SRY gene is failing to function.
Apparent males where they have XX chromosomes and the SRY gene has switched on.
What type of gene is SRY?
It is an architectural transcription factor that sets of a cascade of different transcription factors that cause changes.
What are primordial germ cells and where do they come from?
They are precusors to diploid germ cells and are derived from the epiblast during gastrulation.
What happens after week 7 in the development of the testis?
Cells of the coelomic epithelium penetrate the medullary mesenchyme to form the primitive sex cords.
What happens following the formation of the primitive sex cords?
They surround the primordial germ cells to form seminiferous tubules. The sertoli cells form within the tubules and the leydig cells form inbetween tubules.
What forms the blood testis barrier and what is the purpose of this?
The sertoli cells adhere to one another with tight junctions, adherens and gap junctions. This forms a barrier along the walls of the seminiferous tubules. This prevents the immune system from being able to access the sperm and tightly controls the ions and molecules that pass in and out.
What are the two main products of the testis?
Spermatozoa and hormones
What are the three phases of spermatogenesis?
Proliferation, division and differentiation.
Where does the proliferation phase of spermatogenesis take place?
In the basal compartment of the tubule.
What happens during proliferation in spermatogenesis?
A spermatogonia undergo mitosis into B spermatogonia which divide again into primary spermatocytes, these move into the adluminal compartment through the BTB.
What happens in the division phase of spermatogenesis?
The primary spermocytes undergo the first meiotic division to form secondary spermatocytes. These undergo a second meiotic division to from round spermatids.
What happens in the differentiation phase of spermatogenesis?
The round spermatids elongate to form elongated spermatids and finally mature spermatozoa. During this they form an acrosome, flagella etc.
What is spermiation?
The process of release of sperm into the lumen of the seminiferous tubules by the sertoli cells.
