Image above. Front cover of Developmental Dynamics and image of stage III–V follicles.
a detailed look into anole ovaries
In their study published in Developmental Dynamics, Dr Antonia Weberling (NDWRH) and Dr Bonnie Kircher (MD Anderson) describe 10 consecutive stages of oogenesis.
"Research into oogenesis of squamates (scaled, non-avian reptiles) is scarce and vital to optimise functional studies such as CRISPR-Cas9 genome editing. Merging my reptile reproductive biology background with Antonia's expertise in early embryonic development while also combining our complementary datasets, we could provide a robust characterisation of brown anole egg development." - Dr Bonnie Kircher
Egg production in humans and reptiles
"Mammals are born with a finite number of egg cells. This results in a decline in fertility with age, which is of major clinical interest regarding human fertility preservation in health and disease, but also a major problem for endangered species. Squamates (lizards & snakes) have a infinite number of egg cells due to a structure within the ovary that contains a pool of stem cells that can form new egg cells - the germinal bed. Our study shed light into the structure of this germinal bed in anolis lizards." - Dr Antonia Weberling
This study lays the basis for functional investigations that may provide insight into why lizards have this germinal bed and why mammals lack it.
10 steps to a mature egg
Figure 10 from Developmental Dynamics article (link below). Schematic of follicle development in the brown anole. (A) Schematic drawing of a brown anole ovary. The follicles are annotated with the corresponding developmental stage (Ia-IX). (B) Schematic drawings of follicle developmental stages Ia-IX. Each schematic includes the main characteristics of each stage but is not scaled toward each other.
Dr Weberling & Dr Kircher describe 10 stages of egg maturation. Using cross sections and histological stains as well as scanning electron microscopy and confocal microscopical imaging in addition to CT scans they analysed the volume increase that is tied with yolk acquisition. Analysing the composition of the cells surrounding the egg cell, they defined distinct differences between the individual stages.
Collaborations
This study led by Dr Antonia Weberling and Dr Bonnie K Kircher presents a large collaborative effort across multiple institutions in both the UK and the US without who's support this study would not have been possible.
The field collections of brown were carried out together with Prof Thom Sanger, Loyola University Chicago. Lab work was carried out in the group of Prof Paul Trainor, Stowers Institute for Medical Research, and in the group of Prof Richard Behringer, MD Anderson Cancer Center. Prof Suzannah Williams (NDWRH) and Prof Florian Hollfelder (Department of Biochemistry, Cambridge) provided vital feedback.
For further information
Read the full publication here: Oogenesis and germinal bed morphology of the brown anole (Anolis sagrei).
Kircher BK, Weberling A, et al.
Developmental Dynamics.
DOI: 10.1002/dvdy.70112